Tesis sobre el tema "Sex differences"

An understanding of sex differences in terms of the risk of disease and its influence on therapeutic interventions can lead to improved disease recognition and treatment for women and men. The overall goal of this thesis was to identify gaps in knowledge in the reporting of sex differences in stroke by using a series of systematic approaches to examine the reporting of sex and gender differences more generally and in stroke. First, in order to determine whether funding agencies and peer-reviewed journals in Australia have policies on the collection, analysis and reporting of sex and gender-specific health data, I performed a qualitative survey utilising web-based searches and interviews. Then I narrowed the focus to stroke where I examined the temporal and regional trends in female participation and the reporting of sex differences in randomised controlled trials identified from ClinicalTrials.gov. Finally, three databases were explored to detect where the sex differences were in stroke: (i) a prospective, population-based cohort study, UK Biobank, was used to identify major risk factors in women and men with stroke; (ii) an individual participant data meta-analysis was performed on five large international stroke randomised controlled trials to examine sex differences in outcome and treatment; and (iii) an Australian cohort study on young stroke survivors was examined for sex differences in returning to unpaid work. The statistical methods used for this work were logistic regression, cox regression and multivariable analysis. Analysing results by sex and gender in medical research is important because this may lead to personalised prevention and treatment strategies. In stroke, researchers need to consider enrolling more women in clinical trials and to report results by sex.

While deception is a common strategy in interpersonal communication, most research on interpersonal deception treats the sex as irrelevant in the ability to detect deceptive messages. This study examines the truth and deception detection ability of both male and female receivers when responding to both true and deceptive messages from both male and female speakers. Results suggest that sex may be an important variable in understanding the interpersonal detection probabilities of truth and of lies. An interaction of variables including speakers’ sex, receivers’ sex, and whether the message is truthful or deceptive is found to relate to detection ability. Both women and men were found to be significantly less accurate than chance in judging the veracity of statements made by men, especially when those statements are lies. On the other hand, both women and men were significantly more accurate than chance in judging the veracity of statements made by women, especially when those statements are truthful. This may suggest that men are better deceivers than women, while women seem more transparent in exhibiting feelings about their messages whether being truthful or deceptive. In recalling real life deceptions discovered previously, women reported that they discovered significantly more lies from female sources than from men they knew. This finding may reflect the previous finding that discovering lies told by women is more likely than is discovering lies told by men.

At the age of 13, the 2:1 ratio becomes evident. It entails the fact that after puberty, twice as many females as compared to males suffer from depressive episodes. Much research has been conducted to highlight key contributing factors that aid in the onset and the timing of the 2:1 ratio. Many researchers emphasize hormonal influences and the onset of puberty as key contributors, with theories such as the gonadic theory andthe interactional hypothesis both highlighting the role of hormones in the existence and the emergence of the 2:1 ratio during adolescence. Furthermore, a large variety of researchers emphasize females increased stress sensitivity and stress reactivity as key contributors to the 2:1 ratio. Critically, research concerning hormonal- and stress-related factors will be included. However, an additional focus will be on neurodevelopmental sex differences. This, as brain-based sex differences have been paid too little attention in theories and models concerning the emergence of the 2:1 ratio during adolescence. Results from research conducted to unravel the mystery of sex differences within the adolescent brain emphasize the impact of sex hormones on the maturational sexual differentiation occurring within the adolescent brain. It has been hypothesized that increases in female adolescent depression might occur in accordance with upsurges in peripheral estrogen levels, during puberty. This seems to suggest that there is an interaction between the effects of circulating ovarian hormones in relation to both sexual differentiation in brain organization and depression susceptibility. Hence, the point of this essay is to delineate key contributing factors that potentially govern the existence and onset of the 2:1 ratio during adolescence by emphasizing the areas of (a) sex-based neurodevelopmental factors, (b) hormonal factors and (c) stress-related factors.

Previous research on academic dishonesty in colleges and universities has consistently shown unacceptable rates of cheating, yet inconsistent reports of sex differences in cheating. Sex differences in cheating were studied in relation to sex role orientation and attitudes towards cheating, and in light of a distinction between two types of cheating; cheating to benefit oneself and cheating to benefit another. 256 undergraduate students completed anonymous surveys to tap their sex role orientation, attitudes towards cheating, and reported frequency of cheating. Although females reported having more disapproving attitudes towards cheating than males, they reported engaging in cheating just as much as males. Sex role orientation was not directly related to cheating, but female-associated characteristics were related to attitudes towards cheating, which, in turn, were strongly related to cheating behavior. It was also found that participants reported engaging in more cheating to benefit another person than cheating to benefit themselves.
Department of Psychological Science

Thesis: S.M., Massachusetts Institute of Technology, Department of Biology, 2021
Cataloged from the official version of thesis.
Includes bibliographical references (pages 17-21).
Biological factors that determine sex and drive sexual differentiation have long been established in humans and other mammalian species. Yet there is a limited understanding of the mechanisms by which these factors give rise to sex-biased outcomes in health and disease. Growing evidence for sex differences in preclinical and clinical studies has led to research funding regulations that require clinical studies and drug trials to account for sex as a biological variable. This new wave of interest in sex differences is focused on three aspects: First, what factors show quantitative sex differences at the molecular and cellular levels, and how are they regulated, over the course of a lifetime, by the classic sex-biasing factors, i.e., genes encoded on the sex chromosomes and sex steroid hormones secreted by gonads. Second, can we utilize knowledge of sex differences (e.g., sex-biased gene expression) gained from studying model animals to generate and test hypotheses regarding these sex-driven variables in a multitude of biological functions of interest. Third, can we translate basic knowledge of sex differences into new therapeutic targets/strategies that alleviate sex-biased outcomes in common diseases, developing sex-specific treatments or extending sex-biased protection from one sex to the other. In this thesis, I will first review the fundamental causes of sex differences and the classical strategies used to study sex-biased phenotypes. Next, I will introduce existing mice models (i.e., the "Four-Core-Genotype", XY* and Sex Chromosome Trisomy models) that aid in delineating the effects of sex hormones and sex chromosomes on sex differences. Finally, I will highlight the insights gained from recent studies using these mouse models and discuss the need for a "systems approach" in future studies of sex differences. (276 words.)
by Qinze Arthur Zhang.
S.M.
S.M. Massachusetts Institute of Technology, Department of Biology

Previously, the ability to subitize (i.e. to immediately quantify a small set of items without counting) was thought to occur for sets of up to seven items and was explained using a developmental canonical pattern recognition approach. Unfortunately, this approach was unable to account for the ability to subitize linear or random arrays of items, thereby, inspiring a pattern learning and recognition (through stimulus repetition and systematic variation of a base pattern) approach. The latter approach, however, suggests that subitizing is not an independent psychological process and simply occurs as the result of pattern recognition. Contrary to this view, a recent study by Dehaene and Cohen (1994), employing a condition that did not introduce a pattern recognition confound and using a simultanagnosic patient sample, provided sound evidence to suggest that subitizing is, in fact, a separable psychological process. In addition, and importantly for past research into the localisation of subitizing within the hemispheres (which has usually involved the testing of larger sets), a subitizing boundary of two and possibly three items, much lower than originally expected, was found. Furthermore, and in contrast to previous research, recent evidence from Butterworth (1999), drawn from acalculic patients, has suggested that subitizing is a left hemisphere process. This possibility, in light of possible sex differences in laterality and the previous use of the lack of a right hemisphere advantage to indicate abnormal perceptual asymmetry, suggests some cause for concern. The present study was, thus, carried out in order to determine a subitizing boundary and to investigate the possibility of hemispheric and sex differences in laterality. As such, it provided the first comprehensive investigation into the ability to subitize using randomly generated and presented patterns, and a normal adult sample. A divided visual field task, involving the enumeration of purely random sets of between 2 and 5 items, randomly presented to the left and right visual fields, was employed. Thirty-two undergraduate psychology students (i.e. 16 male and 16 female subjects) volunteered to participate. Based on Dehaene and Cohen's (1994) results it was hypothesised that the subitizing boundary would occur at two and possibly three items. Furthermore, in line with Butterworth's hypothesis, the present study predicted that subitizing would show a left hemisphere advantage. Finally, based on previous research into performance on nonverbal visual tasks, a female subitizing advantage was expected. The results supported the first hypothesis, indicating a subitizing boundary of two items, thereby, extending Dehaene and Cohen's (1994) research using a normal sample. The second hypothesis, however, was not supported, with the results indicating a strong right hemisphere advantage for subitizing. Finally, the third hypothesis was not supported, with no sex differences found in the ability to subitize. These findings were considered both in the context of Butterworth's hypothesis and in the formation of number systems within remote hunter-gatherer societies. Future research involving young children and a cross-cultural perspective, were suggested.

This study examines sex differences in mathematics in Scotland. The study is based on longitudinal data from the 1985 Scottish School Leavers Surve3r of 5726 students in one school district. It compares the distribution of scores for boys and girls on the 1984 Ordinary Grade (O-grade) Arithmetic examination, taken by the majority of Scottish students at the end of compulsory schooling, and matches these results with indicators of male and female ability, socioeconomic status (SES), previous arithmetic achievement in primary school, and destinations upon completion of compulson' schooling. The findings suggest that boys slightly outperformed girls on the O-grade Arithmetic examination. Girls were more likely to present for this examination, but more girls than boys scored at the lower end of the distribution. These differences did not vary substantially for pupils at different levels of ability, SES, or prior achievement in arithmetic. The gender gap in mathematics favoring boys, however, did become significant after the period of compulsory schooling. More girls than boys stayed on at school, but fewer of them elected to take further training in mathematics. Boys took more advanced mathematics courses in the last two years of high school and performed better than girls on those courses. Policy implications of these findings and directions for research are discussed. Teachers and counsellors must become informed about the lack of female persistence in mathematics and take steps to alleviate it. Future research should examine why girls in Scotland do not keep up with boys and the factors that have enabled some girls to overcome this general tendency.
Education, Faculty of
Curriculum and Pedagogy (EDCP), Department of
Graduate

The Coronavirus disease 2019 (COVID-19) outbreak have shown that there may be sex-dependent differences in morbidity and mortality among individuals contracted with the disease. The aim of the study was to analyse the extent that sex differences appear in COVID-19 infections and to explore whether any differences are due to intrinsic factors in the sexes that cause sex-bias in the disease susceptibility and mortality. The study presents an age and sex-disaggregated analysis of reported cases of total infections, intensive care cases, and deaths across 13 countries due to the disease. The results demonstrated that there is a general trend for the disease prevalence, and it shows a female bias among the proportion of individuals infected with COVID-19. However, males appear to require more intensive care treatment and higher rates of death when compared to females. The results also show that more women than men are reportedly infected by the corona virus up to a certain age. After the age of 60, the proportion of men affected is higher than women, and it is also at this age that the death rate among men increases significantly. In conclusion, the results of this work indicate that males could possibly be at a significantly higher risk of severe disease and death than females, and that the patterns of sex bias in intensive care cases to some extent follows the expected pattern if sex hormones played a role in influencing the immune system response to COVID-19.
Utbrottet av Coronavirus sjukdomen 2019 (COVID-19) har visat att det kan finnas könsberoende skillnader i sjuklighet och dödlighet bland individer som drabbats av sjukdomen. Syftet med studien var att analysera i vilken utsträckning könsskillnader förekommer i COVID-19-infektioner och att undersöka om skillnaderna beror på inre faktorer hos könen som möjligtvis orsakar könsfördomar i sjukdomens mottaglighet och dödlighet. Denna studie presenterar en ålder-och könsfördelad analys av totala antalet rapporterade fall, intensivvårdsfall och dödsfall i 13 länder till följd av COVID-19. Resultaten visade att det finns en generell trend för sjukdomens utbredning, och den visar en högre andel kvinnor än män som har smittats med COVID-19. Men det är män som är mer i behov av intensivvård och har högre dödsnivåer i jämförelse med kvinnor. Resultaten visar även att fler kvinnor än män smittas av coronaviruset upp till en viss ålder. Efter 60-årsåldern är andelen drabbade män högre än kvinnor, det är även vid den här åldern som dödsnivån bland män ökar markant. Sammanfattningsvis indikerar resultaten av denna studie att män eventuellt skulle kunna ha en betydligt högre risk för en allvarligare sjukdom och död än kvinnor.

Differences in cognitive performance between boys and girls have been reported in the literature for many years (Maccoby & Jacklin 1974, Bell 2001), but their interpretation remains contentious (Feingold 1992a). Important issues have arisen over such matters as: the methods to be used to assess girls' and boys' performances on cognitive ability and achievement tasks; the appropriate statistical procedures to be used to compare those performances, including meta-analytic procedures; and whether the sex differences are cultural or biological in origin. Although some reported differences are relatively large, there is recent evidence of progressive changes in girl/boy relativities (Nowell & Hedges 1998), suggesting that much of the sex difference in cognitive performance is attributable to non-biological factors. The present research on chemistry problem solving in secondary students is positioned within this literature. As with some other areas of science (Lee & Burkham 1996), and mathematics (Beller & Gafni, 1996; Hedges & Nowell, 1995), the evidence with which the present research commenced indicated that boys' achievement in chemistry was higher, on average, than girls', and that this difference was not attributable to item difficulty confounds (Walding, Fogliani, Over, & Bain, 1994). Of the various explanations considered for this effect, the most promising appeared to be sex-correlated differences in science-related interests and in orientations to sex roles. For example, many students engage in activities, interests and sports that provide them with experiences relevant to science. Such experiences are likely to result in an incidental knowledge and understanding of these domains that the students might otherwise not possess. Sex differences in these science-related experiences may be associated with sex differences in incidental learning and ultimately with performance on formal chemistry tests. A student's sex role orientation, irrespective of biological sex, may also influence her/his experiences of the world in ways that influence the uptake and use of science-related knowledge. The main research reported in this thesis examined these possibilities, culminating in a structural equation model demonstrating sex influences on chemistry problem solving partly mediated by science–related knowledge and sex role orientation. An empirical test of science-related incidental knowledge was developed and trialled with 542 secondary school chemistry students. Clear evidence was found for sex differences in this knowledge (some areas favoured girls, others boys), and the differences thus revealed were used to construct a chemistry achievement test with three sub-scales: one biased in favour of girls' incidental knowledge, another biased in favour of boys, and a third consisting of neutral items. Performance on this test was correlated with students': science-related incidental knowledge; their sex role orientation (Antill & Cunningham, 1982); and their enrolment status for a concurrent physics course (because earlier research suggested this also might be a relevant predictor of chemistry achievement —Walding et al., 1994). Preliminary analyses showed that two of the three chemistry sub-tests performed as expected. The boy-gendered subtest produced a significant difference in scores favouring boys and with the neutral subtest there was no significant difference between boys' and girls' scores. However, the girls' subtest was expected to show a sex difference favouring girls but this did not eventuate. As mentioned above, two main variables were examined as possible factors giving rise to this sex difference in chemistry achievement. The correlation between performances on the boys' science-related incidental knowledge sub-test and the boy-gendered chemistry sub-test supported the notion that incidental knowledge influences achievement on formal chemistry tests. However, no such effect was found for the girls' science-related incidental knowledge and the girl-gendered chemistry sub-test. Although it was found that the science-related incidental knowledge scale was clearly girl-biased, this was not the case with the girl-gendered chemistry sub-test as mentioned above. The absence of a relationship between the two may reflect the lack of a girl bias in the girl biased chemistry sub-test or an absence of a relationship per se. The other variable thought likely to give rise to sex differences in formal chemical knowledge was sex role orientation. Sex role orientation – defined as masculine, feminine, androgynous and undifferentiated – was associated with differential performance on the chemistry test. Firstly, highly masculine students tended to perform significantly better than weakly masculine students on the boy gendered chemistry questions whereas highly feminine students performed significantly better than weakly feminine students on the girl gendered chemistry questions. Lastly, as anticipated, there was no sex role differentiation on the unbiased chemistry questions. However, some inadequacies were apparent with the preliminary analyses and four additional variables were included. Gendered knowledge appeared to be a factor contributing to sex differences in chemistry achievement but the influence of total incidental knowledge was uncertain. Secondly, the effect of masculine and feminine sex orientations was apparent but the influence of non-traditional sex roles was not clear. Both these variables needed to be accounted for in future analyses. The other aspects of interest were the influence of the concurrent curriculum (in this case physics) on chemistry performance and the relationship of the chemistry subscales to a more traditional test of chemistry achievement. The main analysis was motivated by two purposes: one was to take account of all variables simultaneously. Although a variety of commonly used statistical methods were applied to the data to test and control factors for one another‘s joint influence, they did not take account of measurement error, relationships among predictor variables and unequal interval scaling of independent and dependent variables. For better estimates of effects structural equation modelling was adopted. It allows the determination of construct validity of measures and the fit of the model, none of which could be handled by classical regression analysis. The second aim was to incorporate non-gendered aspects of incidental knowledge and sex role orientation in addition to the gendered aspects. To achieve these aims, a complex, multistage, mediated-effects latent variable structural model was hypothesised. The measurement design consisted of latent variables for gendered (bipolar) and non-gendered science related incidental knowledge, traditional (bipolar) and non-traditional sex roles, and a latent variable for general chemistry achievement all of which used the variables described earlier as indicators. The structural design consisted of the direct and indirect influences of sex on each of the chemistry sub-tests, with the indirect effects being defined via gendered and non-gendered science related incidental knowledge latent variables, traditional and non-traditional sex roles latent variables, and a concurrent physics enrolment variable. Several important conclusions were drawn from the structural model. One of the most obvious was that some of the chemistry test performance was sex biased and some not. Some of the influence of sex on these biased parts of the test may derive from prior sex-biased interests in science-related knowledge – an effect resulting from a knowledge difference. However, other influences of sex on the biased parts of the chemistry test may derive from students' sex role orientations – a gender difference. Irrespective of these two 'incidental curriculum' influences – science-related incidental knowledge and sex role orientation – some of the influence may be 'direct', in the sense that it is not attributable to these two major mediating factors under investigation. One interpretation is that there are unmeasured correlates of sex that influenced chemistry achievement; these could include spatial and visual perception (Linn & Petersen 1985), verbal ability (Hyde & Linn 1988), or mathematical ability (Hyde, Fennema & Lamon 1990). However, it is acknowledged that the problem with including more and more mediating variables that correlate with sex and target achievement (in this case the chemistry subtests), is that more and more imperfect substitutes for sex are being added. Hence, it may be possible to eliminate all of the direct sex effect but by splitting it into various surrogates for sex, all imperfect but collectively sufficient to replace sex. It is also possible, however, that neither of the gendered latent variables was optimally defined: a better measurement model might have resulted in a better structural model. As well as the gendered effects of science-related incidental knowledge (which showed that gendered chemistry subtests show sex differences in response to the variety of students‘ knowledge), there were non-gendered effects suggesting that amount of prior relevant knowledge is important for some aspects of chemistry achievement. In cognate areas such as physics, formal courses might act in the same way as the 'incidental curriculum', both being correlated with sex, and perhaps being responsible for differences in chemistry performance, but the mechanism for the influence of incidental and formal knowledge remains an open question. In defining the contributions to the advancement of theory and implications for theoretical advance, the mechanism that underlies the influence of science related incidental knowledge on the learning and assessment of formal chemistry is postulated: one concerns a knowledge uptake effect in which the incidental knowledge of events and phenomena is crucial; the other is a testing effect in which the vagaries of assessment and the notion of fair testing are paramount. In this way the implications for future research are elaborated. But more than build an understanding of the nature and influences of sex differences in cognition – the question is posed: what can we do about it; how can practice be changed? Various possibilities are canvassed, culminating in a description about how the new syllabuses in chemistry and physics in Queensland have been written with these questions in mind.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Curriculum, Teaching and Learning
Full Text

Adolescence is a unique time during the human lifespan, where children develop into reproductively competent adults, and many behavioral and psychological changes develop. The goal of this dissertation is to examine the underlying functions related to the emergence of risky adolescent "behaviors," broadly defined to include both physical risks (e.g., drinking or physical fighting) and psychological risks (e.g., anxious or depressive symptoms). In this paper I (1) present a manuscript reviewing and synthesizing the relevant evolutionary theories, which bears testable hypotheses regarding sex differences in risky adolescent behavior, and (2) empirically assess these predictions in two separate but theoretically and conceptually related studies that test for theoretically-based hypothesized relations: one specific to males, one to females. Specifically, I test the proposition that males should be more likely to engage in physically risky behavior than females, and that females should be more likely to engage in affective risks (assessed as sensitivity to social evaluation). These hypotheses are generally supported, but shed light on important environmental factors that are associated with the prevalence of risk-taking, including the degree of closeness within the family, timing of pubertal development, and social status. In general, an early pubertal development and low social status are associated with risk-taking, while closeness to family buffers against the likelihood of engaging in later risky behaviors.

This study examined the relationship between sex, sex role and expression of depression. The Beck Depression Inventory, The Bem Sex Role Inventory, and the Inventory of Depressive Behaviors were administered to 589 college students. Sex differences in the expression of depression were similar to the findings of previous studies. Sex role differences in the expression of depression were found. Masculine sex role was related to expressive coping strategies along with instrumental strategies. Feminine sex role was related to behavioral and cognitive coping along with more expressive behaviors. The variance in expression of depression accounted for by sex was only partially accounted for by sex role. Undifferentiated individuals were significantly more depressed than Masculine, Feminine or Androgynous individuals, but there were no differences between the latter three groups. Thus, either masculinity or femininity appears to be associated with lower levels of depression.

Males and females differ in morphology and behaviour, so that selection acts differently on the two sexes. This changes the relative reproductive success of males and females, and it is beneficial for parents to bias the sex ratio of their broods in favour of the sex with the best survival and breeding prospects. Differences between the sexes and brood sex ratio in Tengmalm’s owl (Aegolius funereus) in northern Sweden were investigated, using a molecular sexing technique based on PCRamplification of sex-linked CHD1 genes. Among owls caught during autumn migration, females were commoner than males, especially within juveniles. However, in contrast to earlier studies, it was shown that adult males sometimes undertake migratory movements indicatory of nomadism. Measurements of these owls revealed that sexual size dimorphism in Tengmalm’s owl is not as great as previously reported from studies carried out during the breeding season. Females were slightly larger (4% by mass) than males, probably owing to the different roles of males and females during breeding, when this dimorphism is greater. The size difference between male and female nestlings was found to be similar to that for adults in autumn, and to investigate whether this led to differential mortality, the effect of supplementary feeding on mortality of male and female nestlings was studied. Supplementary feeding reduced male mortality when vole abundance was low, and it was concluded that larger female nestlings out-competed their smaller brothers, who then suffered increased mortality when food was scarce. Recruitment of male nestlings into the breeding population declined with decreasing food supply at the time of fledging, a pattern not observed in females. Juvenile males were therefore more vulnerable to food shortage than females, both in the nest and after fledging. Mean brood sex ratio varied significantly among years characterized by different phases of the vole cycle and associated vole abundance. Broods were male-biased (63% males) in a year when the food supply was favourable during spring and summer, neutral (50%) in a year with an intermediate food supply, and female-biased (35% males) in a year when food was in short supply. Parents appeared to adaptively adjust the sex ratio of their broods according to the relative mortality risk and reproductive potential of sons and daughters.

Sex differences in spatial ability, especially mental rotation, navigation and object-location memory are described in this essay. Biological differences in brain morphology, hormones and genes between men and women are presented as explanations for the sex differences. Another level of explanations offered are evolutionary, hence the most influential evolutionary psychological theories are summarized and evaluated. These theories are Gaulin’s and Fitzgerald’s male range theory, Silverman’s and Eals’s hunter-gatherer theory, and Ecuyer-Dab’s and Robert’s twofold selection theory. The hunter-gatherer theory at present seems to be of the most importance, though the twofold selection theory may in the future challenge it. Regardless, united biological and evolutionary explanations would create the best comprehensive theory.

Empathy is a multidimensional phenomenon that consists of both emotional and cognitive components. This paper gives an overview of behavioural and neuroscientific sex differences in empathy, as well as potential explanations to those results. Research indicates existence of sex differences in both emotional and cognitive empathy, although inconsistent findings suggest both female superiority as well as male superiority. Gender roles, social desirability, as well deficiencies in measurement and imprecise conceptualizations of empathy is argued as contributors to found sex differences. With a restricted amount of research on sex differences in empathy, inconsistent findings as well as a great proportion of critique towards both the research field of empathy as well as towards focus on sex differences; the authors argue that presented sex differences in empathy must be interpreted with a great caution. Keywords: empathy, sex, gender difference, behaviour, neuroscience

Background: Schizophrenia first appears in adolescence, in boys at an earlier age than girls. The interpretation of this key epidemiological finding crucially depends on whether similar age-related sex differences exist in the expression of associated, subclinical psychosis-like experiences. Methods: Findings are based on a population sample of 2548 adolescents and young adults aged 17–28. Subjects were assessed with the core psychosis sections on delusions and hallucinations of the Munich- Composite International Diagnostic Interview. Results: The risk of subclinical psychotic experiences was significantly higher for males in the younger half of the cohort (17–21 years), but similar in the older half (22–28 years). Conclusions: These findings suggest that normal maturational changes in adolescence with differential age of onset in boys and girls cause the expression of psychosis, the extreme of which is schizophrenia.

Past research has provided conflicting results concerning sex differences in the desire for status. The current study was designed to examine more explicitly sex differences in the desire to attain status. Eighty girls and 80 boys from kindergarten and grade four were placed in groups of four same-sex friends and were observed during a session in which they had to choose a leader, as well as during a drawing task. The children were also interviewed following the tasks using a questionnaire format. Results showed that there were no sex differences in the number of volunteers to be leader, in the length of time to negotiate who would be the leader, in the degree of positive affect expressed while choosing a leader, or in the degree of involvement in the negotiation of who would be the leader. Results suggest that based on this one study in which status was defined as leadership, no sex differences exist in the desire to attain status, although leadership styles may vary. Results are discussed in terms of the implications of the desire for status for the personality development of females and males.

College student men (n = 185) and women (n = 244) rated how desirable certain characteristics are in an ideal sex partner within a long-term relationship. They reported personal beliefs and predictions about the other gender's preferences. Of the twenty-six items that comprised each measure, factor analyses yielded five subscales: Communication/Openness, Physical Attractiveness, Knowledge/Skill, Take Control, and Response/Drive. As hypothesized, men placed greater emphasis than did women on Physical Attractiveness and Response/Drive, whereas women, more than men, believed Knowledge/Skill was important. Men and women differed completely on what they thought was important to each other. Furthermore, men recognized that there were gender differences on all subscales but Knowledge/Skill, whereas women recognized gender differences on all subscales. When the actual responses of men and women were compared with the beliefs that each had about the other, results showed that both genders underestimated the importance the other placed on Communication/Openness and overestimated that of Physical Attractiveness. Results are discussed with regard to implications for counselors.
Department of Psychological Science

The study investigated biological, cognitive, and social factors relating to the under-achievement of girls compared to boys in mathematics. The phenomenon was investigated of girls being superior to boys in mathematics tests at the primary age but boys being superior to girls from adolescence. Historical considerations appear to have contributed to the delayed provision of mathematics education for girls. Gender differences in tests were found in a few specific classes only and were not the general case. The analysis of errors found that language determines the level of success in mathematics during the early years. Other social factors such as parent attitudes and teacher confidence build up during the primary years to manifest from about the age of eleven and work to the detriment of girls. Secondary age boys demonstrated more positive attitudes than girls, but girls did not demonstrate negative attitudes. The period between the second and fourth year juniors proved to be of significant importance In the development of mathematical achievement. During this period a change occurred in the types of test errors and omissions, the level of career aspirations, the number of male teachers experienced, the extent of whole class teaching, and pupil attitude scores. Teachers did not give more attention to boys compared to girls. A method of attitude assessment was trialled. Results suggested that most pupils viewed the teacher as a disciplinarian even though few discipline related interactions were observed in the classroom study. Male teachers appeared confident in mathematics, whereas females had less positive attitudes. Study of the classroom suggested that the curriculum area being taught influenced the teaching style employed which in turn influenced pupil behaviour. Differences within each curriculum area would allow for classroom factors to have a differential effect on girls and boys in mathematics and not other curriculum areas.

Inspection of the published research shows that sex differences in cognition in the general population have been widely cited with the direction of the advantage depending on the domain being examined. The most prevalent claims are that men are better than women at visuospatial and mathematical tasks whereas women have superior verbal skills and perform better than men on tasks assessing episodic memory. There is also some evidence that women are more accurate than men at identifying facial expressions of emotion. A more in-depth examination of the literature, however, reveals that evidence of such differences is not as conclusive as would at first appear. Not only is the direction and magnitude of sex differences dependent on the cognitive domain but also on the individual tasks. Some visuospatial tasks show no difference (e.g. figure copying) whist men have been shown to be better than women at confrontation naming (a verbal task). Alzheimer’s disease is a heterogeneous illness that affects the elderly. It manifests with deficits in cognitive abilities and behavioural difficulties. It has been suggested that some of the behavioural issues may arise from difficulties with recognising facial emotion expressions. There have been claims that AD affects men and women differently: women have been reported as being more likely to develop AD and showing a greater dementia severity than men with equivalent neuropathology. Despite this, research into sex differences in cognition in AD is scarce, and conflicting. This research was concerned with the effect of sex on the cognitive abilities of AD patients. The relative performance of men and women with AD was compared to that of elderly controls. The study focused on the verbal, visuospatial and facial emotion recognition domains. Data was collected and analysed from 70 AD patients (33 male, 37 female), 62 elderly controls (31 male, 31 female) and 80 young adults (40 male, 40 female). Results showed those with AD demonstrate cognitive deficits compared to elderly controls in verbal and visuospatial tasks but not in the recognition of facial emotions. There were no significant sex differences in either the young adults or the healthy elderly controls but sex differences favouring men emerged in the AD group for figure copying and recall and for confrontation naming. Given that elderly men and women perform equivalently for these tasks, this represents a deterioration in women’s cognitive abilities, relative to men’s. Further evidence of such an adverse effect of AD was apparent in other tasks, too: for most verbal and visuospatial tasks, either an effect favouring women in the elderly is reversed or a male advantage increases in magnitude. There is no evidence of sex differences in facial emotion recognition for any group. This suggests that the lack of published findings reporting on sex differences in this domain is due to the difficulty in getting null findings accepted for publication. The scarcity of research examining sex differences in other domains is also likely to be due to this bias.

Background: Schizophrenia first appears in adolescence, in boys at an earlier age than girls. The interpretation of this key epidemiological finding crucially depends on whether similar age-related sex differences exist in the expression of associated, subclinical psychosis-like experiences. Methods: Findings are based on a population sample of 2548 adolescents and young adults aged 17–28. Subjects were assessed with the core psychosis sections on delusions and hallucinations of the Munich- Composite International Diagnostic Interview. Results: The risk of subclinical psychotic experiences was significantly higher for males in the younger half of the cohort (17–21 years), but similar in the older half (22–28 years). Conclusions: These findings suggest that normal maturational changes in adolescence with differential age of onset in boys and girls cause the expression of psychosis, the extreme of which is schizophrenia.

Certain forms of spatial navigation are centered, neuroanatomically, on the hippocampal formation, a brain structure vulnerable to increased levels of the stress hormone cortisol. Although empirical studies have identified a substantial sex difference, in favor of males, on laboratory-based spatial navigation tasks, little research has investigated whether, and how, these sex differences manifest under conditions of psychological or physiological stress. The current study aimed to resolve some of the inconsistencies in the literature, and to investigate the relations between stress and performance in male and female participants. The current study followed a mixed quasi-experimental pretest-posttest design in which men (n = 23) and women (n = 23) were tested on two separate days (the first day under control conditions and the second under stressful conditions). I utilized a novel stress induction paradigm (the Fear Factor Stress Test) that would produce both hypothalamic-pituitary-adrenal axis and autonomic nervous system activity in men and women, and created a spatial navigation virtual environment task that would allow for cue usage of both landmarks and gradients. Participants also completed the Card Rotations Test as an assessment of their mental rotation abilities. I hypothesized that (a) men would perform better on spatial navigation tasks than women on Day 1 (i.e., the control condition) despite the availability of landmark cues, and (b) stress would affect spatial navigation performance in women more than in men. Results suggested that the stressor used was effective in eliciting appropriate responses in both men and women, however women showed smaller cortisol increases than men, relative to baseline. Regarding the navigation task, under unstressed conditions men showed a steeper learning curve than women in an unchanged environment, and performed better than women only when a proximal landmark cue was removed from the environment. Furthermore, findings suggested that acute psychosocial stress enhanced navigational performance in men, but impaired such performance in women. Regarding the mental rotation task, no sex differences were observed under unstressed conditions; however, under the stressed condition men improved in their performance whereas women were relatively unaffected. It appears then that men's spatial ability might, under particular conditions and on particular tasks, be enhanced following exposure to a stressor. Furthermore, the pattern of results observed in the spatial navigation task suggests that the types of navigation-aiding cues in an environment (as well as location of these cues relative to the target) play a significant role in eliciting sex differences in navigational performance following exposure to a psychosocial stressor.

Doctor of Philosophy
Department of Kinesiology
Craig A. Harms
The overall aim of this dissertation is to further understand sex differences in the cardiopulmonary responses during exercise in younger and older individuals. Emphasis is directed towards the influence of sex in modulating respiratory muscle blood flow and the inspiratory muscle metaboreflex. The first investigation of this dissertation (Chapter 2) demonstrated that sex differences do not alter respiratory muscle blood flow at rest or during exercise. The second investigation (Chapter 3) demonstrated that sex differences exist in the cardiovascular consequences of the inspiratory muscle metaboreflex. Specifically, premenopausal women, compared to age-matched men, exhibited attenuated increases in mean arterial pressure and limb vascular resistance as well as decreases in limb blood flow during inspiratory muscle metaboreflex activation. In Chapter 4, we demonstrated that postmenopausal, compared to pre-menopausal, women exhibit greater increases in mean arterial pressure and limb vascular resistance and decreases in limb blood flow during activation of the inspiratory muscle metaboreflex. Furthermore, no differences in the cardiovascular consequences were present between older men and women or younger and older men with activation of the inspiratory muscle metaboreflex. These data suggest that the tonically active inspiratory muscle metaboreflex present during maximal exercise will result in less blood flow redistribution away from the locomotor muscles in pre-menopausal women compared to postmenopausal women, as well as younger and older men. In conclusion, sex differences in young adults incur a major impact in the cardiovascular consequences during inspiratory muscle metaboreflex activation, while not modifying respiratory muscle blood flow.

Nella ricerca medica, nonostante la crescente evidenza che il sesso potrebbe essere un modificatore dell’effetto dei trattamenti, differenze basate sul sesso nella presentazione, progressione, eventi avversi e nel trattamento delle malattie sono raramente analizzate. Solo nel 2018, Conforti e colleghi hanno evidenziato per la prima volta che considerando pazienti affetti da diversi tipi di tumori in stadio avanzato e trattati con gli inibitori dei checkpoint immunitari, in monoterapia o come terapia combinata, gli uomini ottenevano un beneficio maggiore in sopravvivenza rispetto alle donne. L'obiettivo generale di questa tesi di dottorato è quello di estendere le conoscenze precedenti (limitate) delle differenze basate sul sesso nell'efficacia dell'immunoterapia e di esplorare i meccanismi a livello molecolare che regolano la risposta immunitaria antitumorale negli uomini e nelle donne. In primo luogo abbiamo studiato se, e confermato che, le donne con carcinoma polmonare avanzato traggono maggiore beneficio rispetto agli uomini dalla combinazione della chemioterapia con un anti-PD-1/PD-L1. Abbiamo anche trovato un'interazione tra il sesso e l'efficacia in termini di sopravvivenza di due strategie terapeutiche (anti-PD-1/PD-L1 da soli o in combinazione con la chemioterapia rispetto alla chemioterapia standard) con direzione opposta dell'effetto negli uomini e nelle donne: gli uomini traggono maggior beneficio con un trattamento anti-PD-1 da solo, mentre le donne hanno una migliore sopravvivenza con un anti-PD-1/PD-L1 più chemioterapia. Successivamente abbiamo studiato il dimorfismo di genere della risposta all'immunoterapia contro il tumore del polmone, ipotizzando che l'eterogeneità della risposta a diverse strategie immunoterapeutiche fosse dovuta a differenze nei meccanismi molecolari che guidano la risposta immunitaria antitumorale negli uomini e nelle donne. Abbiamo osservato un minor riconoscimento del tumore e una minore infiltrazione del sistema immunitario negli uomini rispetto alle donne. In particolare, negli uomini, abbiamo riscontrato una minore abbondanza di cellule immunitarie nel microambiente tumorale, un più alto T-cell exclusion score, una minore diversità di repertorio dei recettori delle cellule T e una minore quantità di ubiquitous TCR. Un'infiltrazione immunitaria così povera dei tumori negli uomini potrebbe dipendere da una presentazione dei neoantigeni tumorali meno efficiente al sistema immunitario, a causa dei livelli di espressione più bassi delle molecole di antigene leucocitario umano (HLA) di classe I e II, maggiore frequenza di I perdita di eterozigosi per HLA di tipo I e/o alterazioni in altre componenti del meccanismo di presentazione dell'antigene. Abbiamo anche dimostrato che, tra le vie molecolari e i processi biologici più arricchiti nel microambiente tumorale femminile, ve ne erano molti direttamente correlati alla risposta immunitaria antitumorale. Al contrario, nessuno dei gene sets trovati significativamente arricchiti nei tumori maschili era direttamente correlato alla risposta immunitaria antitumorale. Inoltre, abbiamo fornito un chiaro esempio delle potenziali implicazioni cliniche dei nostri risultati, mostrando differenze significative nell'associazione tra carico mutazionale del tumore e il beneficio di sopravvivenza osservato in uomini e donne trattati con anticorpi anti-PD-1/PD-L1. Abbiamo implementato diversi metodi statistici: le meta-analisi per combinare i risultati di diversi studi; il modello di Cox per analizzare i dati di sopravvivenza; le spline cubiche ristrette come mezzo per indagare gli scostamenti dalla linearità e per modellare la relazione tra covariate continue e gli outcome di sopravvivenza di interesse. Inoltre, abbiamo implementato la metodologia Gene Set Enrichment Analysis nel software statistico SAS con un’estensione alle meta-analisi.
In the last decade lots of research efforts were put in the field of immunotherapy, a relatively new class of treatments that boost the body’s natural defenses to fight against cancer. In medical research, despite growing evidence that sex (i.e., differences between men and women at biological level) might be a disease treatment modifier, sex-based differences in the presentation, progression, adverse events as well as in the prophylactic or therapeutic treatment of diseases were rarely analyzed and reported. Only in 2018, Conforti and colleagues found, for the first time, that considering patients affected by several types of advanced cancers, and treated with immune checkpoint inhibitors as monotherapy or as a combination therapy, males derive larger effect on OS then females do. The overall aim of this doctoral thesis was to extend previous (limited) knowledge on sex-based differences in cancer immunotherapy efficacy and to further explore mechanisms at molecular level that regulate anticancer immune response in men and women. First, we investigated whether, and confirmed that, women with advanced lung cancer derive larger benefit than men from the combination of chemotherapy to an anti-PD-1/PD-L1. We found also an interaction between patients’ sex and the efficacy in OS of two therapeutic strategies (anti-PD-1/PD-L1 alone or in combination with chemotherapy compared to standard chemotherapy) with opposite direction of the effect in men and women: men derive larger benefit than women with an anti-PD-1 treatment alone, while women have better survival with anti-PD-1/PD-L1 plus chemotherapy. Then we deeply studied the sex-based dimorphism of the response to lung cancer immunotherapy, conjecturing that the heterogeneity of response to different immunotherapeutic strategies might be due to differences in the molecular mechanisms that drive anticancer immune response in men and women. We observed a less efficient tumor recognition and infiltration by immune system in men compared to women. In particular, in men, we found a lower abundance of a number of immune cell types in the tumor microenvironment (TME), a significantly higher T-cell exclusion score, a smaller T-cell receptors repertoire diversity and a lower amount of ubiquitous expanded T-cell receptors. We found that such poorer immune infiltration of tumors in men may depend on a less efficient tumor neoantigens presentation to the immune-system, due to lower expression levels of human leukocyte antigen (HLA) class I and II molecules, higher frequency of HLA type I loss of heterozygosity and/or alterations in other component of the antigen presentation machinery. We also showed that, among the molecular pathways and biological processes most significantly enriched in the TME of women, there were many directly related to the anticancer immune response. Contrary, none of the gene sets found significantly enriched in tumors arising in men were directly related to anticancer immune responses. Moreover, we provided a clear example of the potential clinical implications of our findings, showing significant differences in the association between tumor mutational burden and survival benefit observed in men and women treated with anti-PD-1/PD-L1 antibodies. We implemented several statistical methods to answer the different questions depending on the aim of each study. We used meta-analyses to combine results from several studies and to produce estimates of the overall sex-effect of interest. We used cox proportional hazard regression model to analyze survival data and, as a mean to investigate departures from linearity, restricted cubic splines were applied to model the relationship between continuous covariates and the survival outcome of interest. Several bioinformatic tools were used to process the data. Moreover, we implemented the Gene Set Enrichment Analysis methodology in the statistical software SAS with an extension to meta-analysis.

The present study tests a reinforcement model for sex differences in depression. This study examines Biglan, Rothlind, Hops, and Sherman's (1989) hypothesis that although distressed and aggressive behaviors both induce negative emotions in others, the reactions to these behaviors are different: aggressive behavior prompts hostile reactions, whereas distressed behavior prompts solicitousness and deters aggression. Although the Biglan et al. results (1989) indicated that reactions were not influenced by the sex of the person emitting the behavior, this result may be a consequence of the population used. This study examined the hypothesis that reactions of others are influenced by sex-role stereotypes when interactions among acquaintances are evaluated. Two hundred and eighty eight college students rated videotaped scenarios in terms of their feelings and reactions toward a male or female acquaintance engaging in distressed, aggressive, or neutral behavior. The findings; support the hypothesis proposed by Biglan that distressed and aggressive behaviors both induced negative emotions in others, although they elicited different behavioral reactions. That is, distressed behaviors prompted supportive and comforting reactions, whereas aggressive behaviors elicited more hostile, argumentative, and avoiding reactions. This study provides further support for the negative reinforcement hypothesis that proposes that distressed behavior induces negative feelings in others; however, at the same time it prompts others to be solicitous and caring and to refrain from aggressive behaviors (Biglan et al., 1989). However, contrary to expectations, no sex differences were found in the reactions to distressed and aggressive behavior despite the use of methodology more conducive to examining gender specific responses. At this point, the most parsimonious explanation for the findings is that the effect is real, yet small and not very robust.
Department of Psychological Science

Since the early 1970's numerous researchers have been questioning the existence of sex differences in causal attribution. From those who claim differences exist, three models have been proposed: the general externality model, the female self-derogation model, and the female low expectancy model. This study proposed that two variables, sex role and task investment, might mediate the relationship between sex and causal attribution. A structural equation model was proposed and analyzed using LISREL VII (Joreskog & Sorbom, 1989).For this study, 208 undergraduate psychology students were asked to complete the following: a demographic sheet, the Personal Attributes Questionnaire (Spence, Helmreich, & Stapp, 1975), a task investment measure created for this study, a short performance task (10 mathematics or anagram problems), and the Causal Dimension Scale (Russell, 1982).Results did not support the proposed overall model; however, some findings were significant. First, women were more likely to make unstable attributions for success than were men, consistent with the female low expectancy model, but the difference was very small. Also, in the failure condition, masculinity was negatively correlated with stability.Second, women reported being more invested in the tasks and said they had more experience at these tasks than did the men. Additionally, femininity was positively correlated with task investment, contrary to predictions. Finally, outcome was correlated with all three causal attribution dimensions. The perception of success was positively correlated with higher internal, stable, and controllable attributions, suggesting a type of self-enhancement bias for both sexes.
Department of Counseling Psychology and Guidance Services

This study identified gender-related differences in post-exercise peripheral blood flow and body temperature in neutral environment (21ºC). The subjects were 11 male (22 +/- 4 years) and 14 pre-ovulatory female (23 +/- 3 years) recreational runners VO2max: 62 +/- 5 mL/kg • min for men and 55 +/- 5 mL/kg • min for women). Forearm blood flow rectal (Trec) and forearm skin temperatures (Tsk), and forearm vascular resistance (mean arterial pressure/forearm blood flow) were measured pre-exercise (pre), immediately after (t = 0), and every 15 minutes up to 105 minutes (t = 105) post-exercise (45-minute run at 75% of VO2max). ANOVA revealed main gender effects for Trec, Tsk, and forearm blood flow (men > women) as well as for forearm vascular resistance (women > men). Compared to pre-exercise, Trec at t = 0 showed a similar increase in men (1.3ºC) and women (1.2ºC). Trec decreased thereafter to reach pre-exercise level after 25 minutes in men. In women, Trec kept decreasing to reach a lower than pre-exercise level after 60 minutes (p < 0.05). Tsk was similar at pre and t = 0 for both genders. In contrast, Tsk was lower in women than men (29.0 +/- 1.3 versus 30.7 +/- 1.5ºC) at t = 105 (p < 0.05). Forearm vascular resistance was similar in men and women pre-exercise and decreased by about 50% in both groups at t = 0. Between t = 30 and t = 105, the women increased their forearm vascular resistance up to 35% more than did the men. These observations suggest the existence of gender-related differences in thermoregulatory and cutaneous blood flow responses during recovery from submaximal exercise.

Thesis advisor: Scott D. Slotnick
Sex differences exist in both brain anatomy and neurochemistry (Cahill, 2006). Many differences have been identified in brain regions associated with long-term memory including the dorsolateral prefrontal cortex, hippocampus, and visual processing regions (Andreano & Cahill, 2009). There is, however, a paucity of research investigating whether and how these differences translate into differences in functional activity. Part 1 investigated sex differences in the patterns of functional activity in the brain during spatial long-term memory, item memory, memory confidence, and false memory. In addition, a meta-analysis was conducted to identify whether there were consistent sex differences in the brain across different long-term memory types. Part 2 determined whether there were sex differences in the patterns of functional connectivity in the brain during spatial long-term memory. Specifically, differences in functional connectivity between the hippocampus and the rest of the brain in addition to the thalamus and the rest of the brain were investigated. Finally, Part 3 investigated whether the observed differences in the patterns of activity (identified in Chapter 1) had sufficient information to classify the sex of individual participants. The results of Part 3 argue against the popular notion that the average female brain and average male brain are not significantly different (Joel et al., 2015). More broadly, the studies presented in this dissertation argue against the widespread practice of collapsing across sex in cognitive neuroscience
Thesis (PhD) — Boston College, 2021
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Psychology

Orofacial musculoskeletal pain conditions, such as temporomandibular disorder (TMD), are debilitating and often difficult to treat. As with many chronic pain conditions, TMD occurs more frequently in women. Thus, understanding mechanisms underlying sex differences in pain and analgesia is essential for effective pain management in both sexes. This study introduces the potential therapeutic advantage of targeting cannabinoid 1 receptor (CB1) localized in primary afferent neurons under myositis conditions. Although sex differences in CB1 responses are recognized in the CNS, it is not known whether such sex differences exist in the periphery. Therefore, I investigated whether peripheral cannabinoid treatment leads to sex differences in anti-hyperalgesic effects, and whether the effects are mediated by sex differences in CB1 level in trigeminal ganglia (TG) under a rodent orofacial myositis model. Peripherally administered ACPA, a specific CB1 agonist, significantly attenuated inflammation-induced mechanical hypersensitivity in the masseter of male rats. In female rats, a 30-fold higher dose of ACPA was required to produce a reduction in mechanical hypersensitivity. CFA injected in masseter muscle significantly up-regulated CB1 mRNA expression in TG from males, but not from females, and CB1 mRNA levels in TG were positively correlated with the anti-hyperalgesic effect of ACPA. IL-1β and IL-6, elevated in the muscle tissue following inflammation, induced a significant up-regulation of CB1 mRNA expression in TG cultures from male rats. The up-regulation of CB1 was prevented in TG cultures from orchidectomized males, and was restored by testosterone treatment. The cytokines did not alter the CB1 mRNA level in TG from intact or ovariectomized female rats. Neither estradiol nor estrogen receptor blockade had any effect on CB1 expression. Similar results were obtained regarding cytokine-induced regulation of μ-opioid receptor (MOR) in TG, another important peripheral target for pain management. These data indicate that testosterone, but not estradiol, is required for the regulation of CB1 and MOR in TG under inflammatory conditions, which explains the sex differences in the anti-hyperalgesic effects of peripherally administered agonists. These data offer important new insights for the development of mechanism-based sex-specific pharmacological treatment alternatives that can be directed at the peripheral anti-nociceptive systems to ameliorate persistent pain.

Social support is likely to play an especially important role in coping with a cancer diagnosis as it presents a unique set of stressors to the individual. The purpose of this study was to examine biological sex differences in the perceived availability of three modes of social support (emotional, instrumental, and informational), source of support (friends vs. family), and social support seeking behavior in a population of cancer patients. The sample included 71 men and 71 women who had been diagnosed with cancer within two years of the start of the study. No significant sex differences were found in social support seeking; however, results revealed that women perceived greater availability of emotional support as well as greater support from friends on all modes of social support than did men. Implications of these findings and future directions for research are discussed.
Department of Counseling Psychology and Guidance Services

ABSTRACT Childhood and adolescent obesity tends to extend into adulthood and predisposes the individual to some chronic diseases in later life. Body composition is a good parameter for evaluating obesity and nutritional status of children. This study aimed to investigate differences in body fat of Nigerian school children in Makurdi, Nigeria. The study sample consisted of a cross-sectional study of 979 boys and 1036 girls who were aged 9-12 years. Anthropometric measures of stature, body mass, triceps, subscapular and medial calf skinfolds were assessed. Percentage body fat in girls ranged from 15.2-17.4%, which was consistently higher than that in boys, i.e. 10.3- 11.9%. Generally, the girls had higher measures of adipose tissue (sum of skinfolds and percentage body fat) than boys. The Nigerian girls at all ages had higher percentage body fat compared to the boys, which indicates gender differences in the children’s body fatness. The study provides a baseline assessment of body fatness in Nigerian children. Future studies on tracking of percentage body fat in relation to nutritional and fitness levels in Nigerian children are needed so that the children, parents and teachers can obtain reliable information about body composition and health related fitness.

Given the current obesity epidemic in tandem with the aging US population, it is imperative to identify methods for reducing cardiovascular disease (CVD) risk that will be efficacious for both sexes. Arterial stiffness (AS) is an independent risk factor for a first cardiovascular event that increases with advancing age and obesity. Previous studies have found that modest weight loss (WL) of 5 to 10 percent successfully reduces AS and other risk factors for CVD. However, it remains unclear whether WL via caloric restriction reduces AS similarly among sexes. We tested the hypothesis that WL via caloric restriction would reduce AS more in men than women because men accumulate more abdominal visceral fat (VF) and lose more with WL compared with women of similar age and adiposity. To test our hypothesis AS was assessed from measurements of pulse wave velocity and ultrasonography of the carotid artery (Ã -SI). Total body and VF were measured using dual energy x-ray absorptiometry and computed tomography scans, respectively. Subjects underwent a 12-week WL intervention. No baseline differences in AS were observed between sexes. However, men were heavier and demonstrated higher levels of VF while women were fatter and had higher levels of abdominal subcutaneous fat. Contrary to our hypothesis both sexes experienced similar decreases in AS with WL despite greater reductions in VF in men. Our findings suggest that VF loss is not the primary mechanism mediating reductions in AS with WL. Future studies are needed to determine the mechanisms of arterial destiffening with WL.
Master of Science