Dissertations / Theses on the topic 'Gait disorders in old age'

Although footwear has been recognised as a risk factor for falls in older people, it remains unclear as to which features of shoes are beneficial or detrimental to balance. This project aimed to systematically investigate the effects of common shoe features, namely: an elevated heel, a soft sole, a hard sole, a flared sole, a bevelled heel, a high-collar and a tread sole, on balance and gait in older community-dwelling people. The experimental shoes were compared to standard shoes in three studies examining: (i) standing balance, leaning balance and stepping in 29 older people, (ii) centre of mass (COM)-base of support (BOS) margins, vertical and braking loading rates, and perceived shoe comfort and stability in 11 young and 15 older people walking on even and uneven surfaces, and (iii) temporal-spatial gait variables, pelvis acceleration, and gait termination in 10 young and 26 older people, on level, irregular and wet surfaces. Elevated heel shoes impaired overall performance in functional tests of balance and stepping. They were also perceived as lacking comfort and stability and led to a conservative walking pattern characterised by increased step width and double-support time, reduced braking and vertical loading rates and medio-lateral (ML) pelvis accelerations on various surfaces. Soft sole shoes increased lateral COM-BOS margin and step width, indicating reduced ML walking stability. When wearing these shoes, subjects had longer total stopping times and on the wet surface, smaller step lengths and shoe/floor angles at heel strike, suggesting a potential risk of slipping. When wearing high-collar shoes, subjects had better balance as demonstrated by small but significant increases in lateral COM-BOS margin, double-support time and step width, and decreases in ML pelvis accelerations on varying surfaces and in total stopping time on the wet surface. Shoes with hard, flared or tread soles or a bevelled heel did not affect balance. In conclusion, providing that they are fitted, have adequate fastening and perhaps a slip-resistant sole, shoes with a low square heel, a sole of medium hardness (shore A-40) and a high-collar provide the greatest stability for older people when walking on dry, wet and irregular surfaces.

Background: High blood pressure (BP) is the leading risk factor for disease and mortality worldwide. However, risks associated with high BP in very old age (≥ 80 or ≥ 85 years) are not entirely understood, as the majority of scientific studies have been performed with younger populations and existing scientific knowledge about very old individuals is sometimes contradictory. Results of previous studies of very old individuals suggest that the associations of BP with mortality and stroke differ with levels of physical and cognitive function. More studies that are representative of very old individuals, including individuals with multimorbidity, that are of adequate size, involve proper adjustment, and investigate non-linear associations, are needed to investigate these issues. Systolic blood pressure (SBP) decline is common among very old individuals and has been shown to precede adverse events. Previous studies have shown that SBP change is associated with baseline SBP, age, and health-related factors, but determinants of SBP change have not been investigated using comprehensive, multivariate models. The three main aims of this thesis were to investigate, in a sample of individuals aged ≥ 85 years, 1) determinants of SBP change, 2) the association of BP with mortality risk and whether this association differs with respect to gait speed and/or Mini-Mental State Examination (MMSE) score, and 3) the association of BP with stroke risk and whether this association differs with respect to the Barthel Activities of Daily Living (ADL) index and/or MMSE score. Methods: The studies conducted for this thesis were based on data from the population-based Umeå 85+/Gerontological regional database study, which provided cross-sectional and longitudinal data on socioeconomic factors, medical conditions, drug prescriptions, and health-related assessments from 2000 to 2015. Participants were aged 85, 90, and ≥ 95 years, and lived in Västerbotten, Sweden, and Österbotten/Pohjanmaa, Finland. Follow-up assessments were conducted after 5 years. Mortality data were collected after 2 and 5 years, and stroke data were collected after 5 years, from death certificates, medical records, population registers, and the inpatient diagnosis register. Comprehensive multivariate models were developed to investigate determinants of SBP change using multiple linear regression, and to investigate associations of mortality and stroke risks with BP using Cox proportional-hazard regression models. Results: Average (± standard deviation) baseline SBP was 146 ± 23 mm Hg, and average diastolic blood pressure (DBP) was 74 ± 11 mm Hg. Within 5 years, 61% of participants had died and 10% had had incident strokes. Among participants followed for 5 years, the average annual SBP decline was 2.6 ± 5.4 mm Hg. In a multivariate model, SBP decline was associated with later investigation year (p = .009), higher baseline SBP (p < .001), baseline antidepressant drug use (p = .011), incident acute myocardial infarction during follow-up (p = .003), use of a new diuretic drug during follow-up (p = .044), and declining Barthel ADL index scores during follow-up (p < .001). In an age- and sex-adjusted analysis of the total sample, mortality risk was decreased in higher (vs. lower) BP categories (SBP ≥ 165 vs. ≤ 125 mm Hg: hazard ratio [HR] .50, p < .001; DBP 70–74 vs. 75–80 mm Hg: HR 1.32, p = .031). In a comprehensively adjusted analysis of the total sample, SBP was not associated significantly with mortality risk. The associations of SBP with mortality in the gait speed < .5 m/s subcohort corresponded with those found in the total sample. In comprehensively adjusted analyses in the gait speed ≥ .5 m/s subcohort, mortality risk increased independently with higher (vs. lower) BP (SBP ≥ 165 vs. 126–139 mm Hg: HR 2.13, p = .048; DBP > 80 vs. 75–80 mm Hg: HR 1.76, p = .026). In comprehensively adjusted analyses in the MMSE score subcohorts, SBP was associated significantly with mortality risk only in the 0–10 MMSE score subcohort; high and low SBP categories were associated independently with increased mortality risk, compared with an intermediary SBP category (SBP ≥ 165 vs. 126–139 mm Hg; HR 4.54, p = .007; SBP ≤ 125 vs. 126–139 mm Hg: HR 2.23, p = .023). Higher BP was associated significantly with increased stroke risk in multivariate models (SBP per 10 mm Hg increment: HR 1.19, p < .001; DBP per 10 mm Hg increment: HR 1.26, p = .013). SBP was not associated with stroke risk in participants with SBP < 140 mm Hg. Interaction effects on the association with mortality were significant between SBP and gait speed (age- and sex-adjusted model: p = .031) but not between SBP and MMSE score. No interaction in the association with stroke was found between any BP measure and Barthel ADL index or MMSE score. Conclusion: The decline in BP in very old age may be explained by health-related factors. Low BP may be a risk marker for short life expectancy, due to morbidity, in the general very old population and among very old individuals with low gait speeds. High BP seems to be an independent risk factor for mortality only in certain groups, which may be distinguished by high gait speed or very severe cognitive impairment. High SBP and DBP seem to increase stroke risk in very old age. These findings may contribute to a better understanding of the risks of adverse outcomes in very old individuals with different BP levels, the importance of comorbidity for these risks, and the etiology of SBP change.
Bakgrund: Högt blodtryck är den största bidragande orsaken till sjukdom och död i världen. Man har ännu inte fastslagit om högt blodtryck ökar risken för sjukdom och död även i mycket hög ålder, vilket kan definieras som 80 år och äldre. Detta beror bland annat på att endast en liten andel av forskningen hittills har fokuserat på den här åldersgruppen. Mycket gamla människor skiljer sig från yngre på olika sätt som skulle kunna påverka riskerna med högt blodtryck. Till exempel är det vanligare med sjukdomar och att ha många samtidiga sjukdomstillstånd bland mycket gamla människor än i yngre åldersgrupper. Då andelen mycket gamla människor i befolkningen ökar kraftigt får dessa frågor allt större betydelse. Det är vanligt med sjunkande blodtryck i mycket hög ålder, något som verkar föregå sjukdom och död. Tidigare studier har funnit att sjunkande blodtryck skulle kunna bero på ökande sjuklighet, högre ålder och högre begynnelseblodtryck. Man vet ännu inte vilka enskilda faktorer som bäst förklarar blodtrycksförändringen i mycket hög ålder, oberoende av andra faktorer. Tidigare studier har visat att lägre blodtryck kan vara förenat med en ökad risk för tidig död bland mycket gamla människor. Det är oklart om risken för tidig död bättre kan förklaras av andra faktorer, s.k. störfaktorer. Störfaktorer kan till exempel vara sjukdomar som både påverkar blodtrycket och risken. Fynd från tidigare studier av personer som är minst 65 år tyder på att sambandet mellan blodtryck och död kan skilja sig mellan grupper med hög eller låg gånghastighet, vilket används som ett ungefärligt mått på hälso-tillståndet. Detta skulle även kunna ha betydelse för mycket gamla människor eftersom deras hälsotillstånd kan skilja sig mycket mellan individer. Man har också utrett huruvida sambandet mellan blodtryck och död skiljer sig mellan grupper med och utan kognitiv svikt, som till exempel kan bero på demenssjukdom, men inte kommit fram till entydiga resultat. Ett fåtal studier har utrett strokerisken med högt blodtryck i mycket hög ålder. På grund av motsägelsefulla resultat är det ännu oklart om högt blodtryck ökar risken för stroke bland mycket gamla människor. Man har sett tecken på att sambandet mellan blodtryck och strokerisk skulle kunna skilja sig mellan grupper av mycket gamla människor med och utan kognitiv svikt, samt mellan grupper med och utan hjälpbehov i dagliga aktiviteter. Dagliga aktiviteter innefattar bland annat att tvätta sig, klä sig, gå på toaletten, äta och resa sig från en stol. Frågeställningar: I den här avhandlingen undersöktes huvudsakligen tre frågeställningar. Den första var vilka faktorer som påverkar hur blodtrycks-nivåerna förändras över tid i mycket hög ålder. Den andra frågeställningen var om olika blodtrycksnivåer är förenade med ökad risk för tidig död i mycket hög ålder och huruvida risken skiljer sig mellan grupper av mycket gamla människor med olika gånghastighet eller olika grader av kognitiv svikt. Den tredje frågeställningen var om olika blodtrycksnivåer är förenade med ökad risk för stroke i mycket hög ålder och om risken skiljer sig mellan grupper av mycket gamla människor med och utan kognitiv svikt eller hjälpbehov i dagliga aktiviteter. Även skillnader mellan gånghastighets-grupper testades. Metod: Avhandlingen bygger på befolkningsmaterialet Umeå85+/Gerontologisk regional databas (GERDA). Umeå85+/GERDA innehåller information från individer i åldrarna 85, 90 och 95 år och äldre, boende i Västerbotten, Sverige och Österbotten/Pohjanmaa, Finland. Informationen är insamlad vart femte år under perioden 2000-2015. Umeå85+/GERDA innehåller information om socioekonomiska faktorer, sjukdomar och läkemedel. Informationen inhämtades med hjälp av ett standardiserat frågeformulär som deltagarna besvarade under ett hembesök, samt med hjälp av journaler, boendepersonal och anhöriga. Det gjordes även hälsorelaterade mätningar och tester under hembesöken, bl.a. av blodtryck och gånghastighet i vanlig takt. Skattningsskalorna Mini-Mental State Examination (MMSE) och Barthel Activities in daily living (ADL) index användes för att skatta kognitiv funktion respektive hjälpbehov i dagliga aktiviteter. Deltagarna delades in i två gånghastighetsgrupper. Personer med högre gånghastighet (minst 0,5 m/s) utgjorde en grupp. I den andra gruppen var personer med lägre gånghastighet (under 0,5 m/s) och de som inte klarade av att genomföra testet på grund av bestående begränsningar av gångfunktionen. Deltagarna grupperades också med avseende på olika grader av kognitiv svikt. Gruppindelningen baserades på MMSE-poäng; mycket svår kognitiv svikt (0-10 poäng), svår kognitiv svikt (11-17 poäng) och mild kognitiv svikt (18-23 poäng). Deltagare utan kognitiv svikt utgjorde en egen grupp (24-30 poäng). Deltagarna delades även in i grupper med och utan hjälpbehov i dagliga aktiviteter, baserat på Barthel ADL index (under 20 respektive 20). Blodtrycksförändring observerades över tiden mellan två Umeå85+/GERDA-insamlingar, vilket var 5 år. Dödsdatum och datum för stroke inhämtades från dödsbevis, befolkningsregister, journaler och sjukvårdens diagnoskodsregister i upp till 5 år. Frågeställningarna utreddes med hjälp av statistiska metoder, baserat på materialet från Umeå85+/GERDA. Sambanden prövades med avseende på störfaktorer och skillnader mellan grupper. Resultat: Förändringar av det systoliska blodtrycket undersöktes bland 297 deltagare. I genomsnitt sjönk blodtrycket med 2,6 mm Hg per år. För nästan två tredjedelar (62%) av deltagarna sjönk blodtrycket med minst 5 mm Hg på 5 år. Ungefär en fjärdedel (26%) hade minst 5 mm Hg stigande blodtryck på 5 år. Ett antal faktorer var förenade med förändring av det systoliska blodtrycket över 5 år, oberoende av varandra. Sjunkande systoliskt blodtryck var förenat med ett högre begynnelseblodtryck, senare undersökningsår, att ha antidepressiv behandling, att få en hjärtinfarkt, att påbörja läkemedels-behandling med diuretika eller få ökat hjälpbehov i dagliga aktiviteter. Man vet ännu inte vad som är orsak och verkan i dessa samband. Frågeställningen om olika blodtrycksnivåer är förenade med ökad risk för tidig död undersöktes i ett urval av 806 deltagare. Inom 5 år avled nästan två tredjedelar (61%) av deltagarna. Risken för tidig död var mindre bland deltagare med högre blodtryck, jämfört med dem som hade lägre blodtryck. Största skillnaden uppmättes mellan deltagare med minst 165 mm Hg i systoliskt blodtryck, där risken var halverad, jämfört med dem som hade 125 mm Hg eller lägre. Detta samband verkar bero på störfaktorer, främst sjukdomar, som både orsakar lågt blodtryck och den ökade risken för tidig död. Gånghastighetsgrupperna utgjordes av 312 deltagare med högre gånghastighet och 433 med lägre gånghastighet, varav 136 inte kunde genomföra mätningen på grund av bestående begränsning av gångfunktionen. Sambandet mellan blodtryck och risken att dö inom 5 år verkade skilja sig mellan gånghastighetsgrupperna. Gruppen med lägre gånghastighet uppvisade samma samband som hela urvalet och hade ökad risk för tidig död med lägre blodtryck. Även här verkade sambandet förklaras av störfaktorer. Personer med högre gånghastighet uppvisade ett annat samband, där högre systoliskt blodtryck på minst 165 mm Hg var förenat med en fördubblad risk för tidig död, jämfört med 126-139 mm Hg. Högre diastoliskt blodtryck på över 80 mm Hg var också förenat med ökad risk för tidig död, jämfört med 75-80 mm Hg. Sambandet berodde inte på störfaktorer. Grupperna med svår, måttlig och mild kognitiv svikt innehöll 118, 166 och 289 deltagare vardera. Gruppen utan kognitiv svikt innehöll 542 deltagare. Dessa grupper verkade också skilja sig något med avseende på sambandet mellan blodtryck och risken för tidig död, men skillnaderna var inte statistiskt säkerställda. Särskilt gruppen med mycket svår kognitiv svikt uppvisade ett annorlunda samband mellan systoliskt blodtryck och risken för tidig död, jämfört med övriga deltagare. Bland dessa deltagare var risken för tidig död mer än fyrdubblad med höga blodtryck på minst 165 mm Hg, jämfört med 126-139 mm Hg. De med blodtryck 125 mm Hg eller lägre hade dubbelt så hög risk för tidig död, jämfört med 126-139 mm Hg. Dessa samband var oberoende av störfaktorer. Frågeställningen om strokerisk med högt blodtryck utreddes i ett urval av 955 deltagare. Inom 5 år fick 94 deltagare en stroke, vilket motsvarar en av tio. Högre blodtryck var förenat med ökad risk för stroke, jämfört med lägre blodtryck. Risken att få en stroke inom 5 år var fördubblad bland deltagare med högt systolisk blodtryck på minst 160 mm Hg, jämfört med under 140 mm Hg, eller med höga diastoliska blodtryck på minst 90 mm Hg, jämfört med under 90 mm Hg. Sambanden var oberoende av en mängd andra riskfaktorer. Strokerisken med högt blodtryck verkade inte påverkas av gånghastigheten, den kognitiva nivån, eller hjälpbehovet i dagliga aktiviteter. Slutsatser: Blodtrycket verkar sjunka hos de flesta i mycket hög ålder. Sjunkande systoliskt blodtryck kan till stor del förklaras av högre begynnelseblodtryck, senare undersökningsår, att ha antidepressiv läkemedelsbehandling, att få en hjärtinfarkt, att påbörja läkemedels-behandling med diuretika eller få ökat hjälpbehov i dagliga aktiviteter. Lågt blodtryck verkar i mycket hög ålder vara ett tecken på olika underliggande sjukdomsprocesser, som ökar risken att dö inom 5 år. Detta samband verkar särskilt gälla personer med lägre gånghastighet, vilket kan vara ett tecken på sämre hälsa. Högt blodtryck verkar endast vara förenat med ökad risk för tidig död i särskilda grupper, som kan utmärkas av högre gånghastighet eller mycket svår kognitiv svikt. Även lågt systoliskt blodtryck kan vara förenat med ökad risk för tidig död bland personer med mycket svår kognitiv svikt. I dessa grupper kan sambandet vara oberoende av störfaktorer. Högre blodtryck verkar vara förenat med ökad risk för stroke i mycket hög ålder, oberoende av en mängd andra sjukdomstillstånd. Det finns sannolikt en gräns för hur lågt blodtryck som är gynnsamt med avseende på strokerisken, men det är ännu inte klarlagt var den gränsen går. Sambandet mellan högt blodtryck och strokerisk verkar inte skilja sig mellan grupper med olika hög gånghastighet, kognitiv nivå, eller hjälpbehov i dagliga aktiviteter. Dessa fynd kan bidra till en bättre förståelse för blodtrycksförändring, risker med högt och lågt blodtryck i mycket hög ålder samt hälsotillståndets betydelse för dessa risker.

Thesis (Ph. D.)--University of Oregon, 2008.
Typescript. Includes vita and abstract. Includes bibliographical references (leaves 88-96). Also available online in Scholars' Bank; and in ProQuest, free to University of Oregon users.

Community locomotion is threatened when older individuals are required to negotiate obstacles, which place considerable stress on the musculoskeletal system. The vulnerability of older adults during challenging locomotor tasks is further compromised by age-related strength decline and muscle atrophy. The first study in this investigation determined the relationship between the major muscle groups of the lower body and challenging locomotor tasks commonly found in the community environment of older adults. Twenty-nine females and sixteen males aged between 62 and 88 years old (68.2 ±6.5) were tested for the maximal voluntary contraction (MVC) strength of the knee extensors and 1-RM for the hip extensors, flexors, adductors, abductors, knee extensors and flexors and ankle plantar flexors. Temporal measurements of an obstacle course comprising four gait tasks set at three challenging levels were taken. The relationship between strength and the obstacle course dependent measures was explored using linear regression models. Significant associations (p≤0.05) between all the strength measures and the gait performances were found. The correlation values between strength and obstructed gait (r = 0.356-0.554) and the percentage of the variance explained by strength (R2 = 13%-31%), increased as a function of the challenging levels, especially for the stepping over and on and off conditions. While the difficulty of community older adults to negotiate obstacles cannot be attributed to a single causal pathway, the findings of the first study showed that strength is a critical requirement. That the magnitude of the association increased as a function of the challenging levels, suggests that interventions aimed at improving strength would potentially be effective in helping community older adults to negotiate environmental gait challenges. In view of the findings of the first study, a second investigation determined the effectiveness of a progressive resistance-training program on obstructed gait tasks measured under specific laboratory conditions and on an obstacle course mimicking a number of environmental challenges. The time courses of strength gains and neuromuscular mechanisms underpinning the exercise-induced strength improvements in community-dwelling older adults were also investigated. The obstructed gait conditions included stepping over an obstacle, on and off a raised surface, across an obstacle and foot targeting. Forty-three community-living adults with a mean age of 68 years (control =14 and experimental=29) completed a 24-week progressive resistance training program designed to improve strength and induce hypertrophy in the major muscles of the lower body. Specific laboratory gait kinetics and kinematics and temporal measures taken on the obstacle course were measured. Lean tissue mass and muscle activation of the lower body muscle groups were assessed. The MVC strength of the knee extensors and 1-RM of the hip extension, hip flexion, knee extension, knee flexion and ankle plantar flexion were measured. A 25% increase on the MVC of the knee extensors (p≤0.05) was reported in the training group. Gains ranging between 197% and 285% were recorded for the 1-RM exercises in the trained subjects with significant improvements found throughout the study (p≤0.05). The exercise-induced strength gains were mediated by hypertrophic and neural factors as shown by 8.7% and 27.7% increases (p≤0.05) in lean tissue mass and integrated electromyographic activity, respectively. Strength gains were accompanied by increases in crossing velocity, stride length and reductions in stride duration, stance and swing time for all gait tasks except for the foot targeting condition. Specific kinematic variables associated with safe obstacle traverse such as vertical obstacle heel clearance, limb flexion, horizontal foot placements prior to and at post obstacle crossing and landing velocities resulted in an improved crossing strategy in the experimental subjects. Significant increases in the vertical and anterior-posterior ground reaction forces accompanied the changes in the gait variables. While further long-term prospective studies of falls rates would be needed to confirm the benefits of lower limb enhanced strength, the findings of the present study provide conclusive evidence of significant improvements to gait efficiency associated with a systematic resistance-training program. It appears, however, that enhanced lower body strength has limited effects on gait tasks involving a dynamic balance component. In addition, due to the larger strength-induced increases in voluntary activation of the leg muscle compared to relatively smaller gains in lean tissue mass, neural adaptations appear to play a greater contributing role in explaining strength gains during the current resistance training protocol.

Falls and gait impairment in older populations present a major challenge to healthcare systems and reduce quality of later life. There is evidence that cognitive decline contributes to falls and gait impairment in older adults and may, therefore, serve as a marker for persons at risk. Intraindividual variability (IIV; trial-to-trial fluctuations in response time across a neurocognitive task) may have screening potential in this respect as this measure is thought to capture unique information about cognitive function not captured by other neuropsychological metrics. The present research, therefore, examined relationships between IIV, gait and falls in cognitively intact older adults. The extent to which relationships varied according to age and the demands placed on the individual when assessing IIV and gait, was also investigated. Finally, a mediational approach identified potential mechanisms underpinning these relationships. Systematic reviews of published research were followed by cross-sectional experimental studies and a longitudinal investigation. The findings provided mixed evidence of a link between IIV and falls. There was strong cross-sectional evidence that greater IIV was associated with poorer gait performance, and that this relationship strengthened with increasing age. Variability better predicted gait outcomes when gait was assessed under more demanding dual-task conditions, and when IIV measures were derived from tasks with higher executive demands. Tests of mediation suggested that processing speed underpinned relationships between IIV and less demanding single-task gait, whereas executive function played a greater role in more demanding gait conditions. Together, the outcomes suggest that IIV measures have potential as an early screening tool for gait impairment, and also falls. Importantly, general slowing accounts of cognitive ageing explained findings when IIV and gait were assessed under lower demand conditions, whereas frontal lobe/executive control perspectives provided a better account when demands were greater.

Semantic knowledge was investigated in patients diagnosed with Dementia of the Alzheimer's Type (DAT) by means of an off-line probe question battery and an on-line measurement of semantic priming in a lexical decision task (LDT) that varied the stimulus onset asynchrony (SOA). The patients' performance on the detailed probe questions showed that their semantic deficit was confined primarily to animate concepts, characterized by visual descriptive features. In the primed LDT, demented patients demonstrated increased semantic priming compared to age-matched controls. A trend was also found indicating that for both normal controls and DAT subjects the priming magnitude decreased as the SOA increased. These results are interpreted in terms of a distributed representation of semantic knowledge that is impaired in demented patients.

Introduction: Cognitive impairment (CI) in older adults refers to impairment in cognition function beyond normal aging. Previous studies have reported the effect of dietary antioxidants, especially flavonoids on cognitive function in older adults, suggesting that high dietary flavonoids intake may reduce the risk of cognitive impairment. However, most of these studies were reported in Caucasian older populations in Western countries. Moreover, some studies were positive, which others were negative studies. There was no previous study regarding dietary flavonoids and cognitive impairment among Chinese older adults. Objectives: The objectives of this study were to explore the association between dietary intake flavonoids and the risk of cognitive impairment in Chinese older adults, and to identify the independent factors associated with the risk of cognitive impairment in Chinese older adults. Method: This study was a retrospective cross-sectional study, 200 patients who fulfilled the inclusion and exclusion criteria and gave written informed consent were recruited from the Geriatric clinics in Queen Mary Hospital, Hong Kong, from 11th July to 31st October 2011. All recruited subjects were invited to attend face-to-face interviews. Brief cognitive assessments by the Mini Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) were done for all subjects. Every subject also answered a detailed questionnaire on socio-demographic, type and frequency of diet items (food frequency questionnaire) and co-morbid diseases. Main outcome measure: The primary outcome measure was cognitive function, using an education-adjusted MMSE cut-off s to categorize the subjects into two groups (i.e. normal cognitive group and cognitively impaired group). Results: 200 subjects were recruited, 104 participants (37 males and 67 females) were in the normal cognitive group and 96 subjects (22 males and 74 females) were in the cognitively impaired group. The mean amount of dietary flavonoids intake of the cognitively normal group was higher than that of the cognitively impaired group (i.e. 291.84 grams/day and 240.92 grams/day respectively; p=0.006 Mann-Whitney U test). Other common dietary nutrients were also compared between the two groups. The dietary carbohydrate (p<0.001), total sugar (p<0.001), vitamin C (p=0.001) and folic acid (p<0.001) intakes were significantly related to cognitive impairment (using chi-square statistics). After adjustment for age, gender, education, exercise pattern, the dietary flavonoids intake was not independently associated with cognitive impairment. However, after adjustment for age, education level, exercise pattern and BMI, the higher to highest quartile of dietary carbohydrate intake (184.184-1176.703g/d), high total sugar intake (0.166-35.102g/d), highest quartile of vitamin C intake (139.803-900.952mg/d), the third and fourth quartiles of folic acid intake (208.899-1544.418mcg/d) were significantly associated with reduced risks of cognitive impairment. Older adults who had regular exercise (both less and more than 30 minutes per day) had lower risk of cognitive impairment than those who never did exercise (OR= 0.361, 95% confidence interval=0.167-0.784 for less than 30 minutes/d; OR=0.137, 95% confidence interval=0.048-0.396 for more than 30 minutes/d). We also found high BMI was associated with a reduced risk of cognitive impairment with an OR of 0.897 (95% confidence interval=0.816-0.987). Besides, the increasing age was also associated with cognitive impairment (OR=1.059, 95% confidence interval=1.007-1.115). Conclusion: In summary, the present study demonstrated that the dietary flavonoids intake was not significantly associated with the risk of cognitive impairment in Chinese older adults in Hong Kong.
published_or_final_version
Medicine
Master
Master of Medical Sciences

Thesis (Ph. D.)--University of Sydney, 2008.
Title from title screen (viewed 18 June 2008). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the Department of Clinical Ophthalmology and Eye Health, Faculty of Medicine. Degree awarded 2008; thesis submitted 2007. Includes bibliographical references. Also available in print form.

Dementia is a growing social problem in Australia because as the population ages, the incidence of dementia increases. While the prevalence rates are only about I% at age 65, they double every five years until by 85 years of age the rate is over 24%. It is expected that by the year 2030, the number of elderly people with dementia will increase by 200%. Dementia is easily recognized in its advanced stages but can be overlooked in the early phase. Family members, care-givers and even the treating medical practitioner may mistakenly attribute the early decline in mental function to the normal aging process. A diagnostic instrument that is easy to administer and score yet is sensitive and specific to the detection of cognitive impairment in the elderly may prove to be of significant benefit to clinicians and assist care-givers and family members in treatment decisions, accommodation requirements and the timely provision of a range of support services. This study investigates the use of the Cognitive Status Examination (CSE) for detecting brain impairment in elderly people. The Cognitive Status Examination comprises the Cognitive Difficulties Scale and a Letter Symbol Substitution Task. It was developed as a screening instrument to detect Alcohol Related Brain Impairment and has proved to be 80% sensitive and 88% specific in detecting brain impairment in that group. This study extended those results to males and females aged 65 years and over with early dementia. A sample of 58 community-dwelling, elderly people aged 65 years and above and a clinical sample of 44 in-patients who were diagnosed with early dementia completed the Cognitive Status Examination. An existing groups, quasi-experimental research design was used. The Cognitive Status Examination proved to be marginally useful as a screening instrument for detecting cognitive impairment in elderly people with early stage dementia with a sensitivity of 59% and a specificity of 93% when the original cut-off scores were used. A revised cut-off score, determined by trial and error, was developed. This resulted in a sensitivity of 86.2% and a specificity of 77.3%, but even with such ad hoc adjustments the CSE fell marginally short of the required 80% for both specifications. Use of the CSE may enable clinicians to utilize existing resources more effectively by referring elderly people in need to appropriate medical care, accommodation and community support services, but further research is required to confirm the revised cutting scores for the CSE. Regression analysis showed that a combination of the raw LST score and the BDI score gained over 90% sensitivity and specificity, and such an actuarial approach also shows promise for future development.

The purpose of the study was to validate the use of the Geriatric Functional Rating Scale (GFRS) in assessing cognitively impaired individuals 65 years of age and older to determine the need for institutionalization. The population of interest consisted of individuals 65 years of age and older exhibiting cognitive impairment and residing in Delaware County, Indiana. A nonrandomized two-group experimental design was utilized for the study. Eighty subjects were selected from two subpopulations consisting of 40 institutionalized and 40 noninstitutionalized elderly.Two geriatric assessment tools were used for the study, the Mental Status Questionnaire (MSQ) and the Geriatric Functional Rating Scale (GFRS). The hypothesis for the study stated that the mean GFRS score of the noninstitutionalized subjects, the control group, would be significantly greater than the mean score of the institutionalized subjects, the experimental group.The MSQ scores as well as the means and standard deviations for the seven subscales of the GFRS were reported for the two groups. A one-tailed t-test was used to test the hypothesis. A decision with regard to the hypothesis was made at the .05 level.Findings of the study included the following:1. The subjects ranged in age from 65 to 92 years, were 90 percent female, and predominantly Protestant, 88 percent.2. The MSQ scores for the combined groups ranged from minimal cognitive impairment, 71 percent, to severe cognitive impairment, four percent.3. The total mean score on the GFRS for the institutionalized group was 6.8 indicating a need for institutionalization.4. The total score on the GFRS of the noninstitutionalized was over 10 times higher at 70.7.5. The noninstitutionalized group scored significantly higher in the GFRS (p<.00) than the institutionalized counterparts.In conclusion, the research supports the use of the Geriatric Functional Rating Scale in assessing the need for institutionalization in cognitively impaired individuals, 65 years of age and older in Delaware County, Indiana.
Department of Educational Administration and Supervision

Thesis (Ph. D.)--University of Oregon, 2003.
Typescript. Includes vita and abstract. Includes bibliographical references (leaves 157-170). Also available for download via the World Wide Web; free to University of Oregon users.

The number of adults in the United States who are age 65 or older is rapidly increasing. With longer lifespan comes an increase in chronic diseases such as dementia, diabetes, and depression. This study used archival data from a larger study conducted at the Memory Clinic at John Peter Smith County Hospital in Ft. Worth, Texas to examine several hypotheses and research questions related to the influence of type of dementia, presence of Type II diabetes, and presence of depression on neuropsychological test performance. First, this study attempted to identify specific patterns of performance on neuropsychological measures for those with Alzheimer's dementia (AD), vascular dementia (VaD), or mild cognitive impairment (MCI). The results indicated that those with MCI perform better than those with AD or VaD on all neuropsychological measures, and that those with VaD perform better than those with AD on a measure of verbal memory. Another purpose of the study was to determine how the presence of Type II diabetes affects this pattern of functioning; the overall finding in this study was that the presence or absence of diabetes did not affect performance on measures of cognitive functioning. Additionally, the study attempted to add to literature examining the influence of depression on older adults with diabetes and/or dementia; no significant differences emerged.

Both the number and proportion of the elderly and people with chronic disability are increasing as a proportion of the entire population, particularly in the over 80 years age range. The most common cause of chronic visual disability in the elderly is age-related maculopathy (ARM). Chronic visual disability, manifested as functional limitations of activities of daily living, often results in psychosocial handicap due to ineffective coping skills. Both low vision services and low vision research have previously been oriented toward functional adjustment to disability, rather than psychosocial aspects of vision loss. Previous disability research has sought to explain psychosocial adjustment in terms of mediators of stress, such as involved in "stress and coping" theory. Recent research interest in measures of rehabilitation outcome have used psychosocial factors as key indicators of adjustment. This study investigates both mediators and measures of psychosocial adjustment to chronic vision loss using a modified stress and coping model. The study consisted of two groups: thirty elderly people with vision loss due to age-related maculopathy (ARM), and thirty elderly people (controls), age-matched and sex-matched to the ARM group but with normal vision. Data were collected, in an interview format in subjects' homes, on four psychosocial scales (life satisfaction, daily hassles, social support, and self-esteem) and a measure of self-care. In addition, information on history of visual impairment, use of optical devices, use of rehabilitation resources, distance and near visual acuity, and demographic factors were also collected. In terms of the model presented, psychosocial results confirmed several, but not all relationships defined within the model and it appears to serve as a useful framework with which to understand the mediating factors in psychosocial adjustment to age-related vision loss. The results tend to suggest that people with chronic age-related vision loss report poorer psychosocial adjustment (as indicated by significantly poorer life satisfaction and greater stress) than age- and sex-matched controls, perhaps as a result of poorer perceptions of social support, despite rehabilitative attention. Several results have implications for the functional rehabilitation of ARM. ARM subjects were found to have significantly poorer mobility and fewer daily activities than control subjects. Reading, recognised as important for both survival and recreational activities for many people with ARM, requires regular follow-up, as indicated by results showing gradual deterioration in vision in the ARM group being associated with poor satisfaction with prescribed reading devices, despite the majority of subjects still using the device daily. People with ARM would therefore seem to prefer to persevere with a coping strategy that is unsatisfactory in order to retain some independence in functioning. Despite several of the individual psychosocial measures used demonstrating their usefulness as measures of psychosocial adjustment, the validity of each of the measures used is questioned. Although the methodology herein does not allow interpretation as to predictors of psychosocial adjustment following onset of vision loss (or indeed following rehabilitation services), interpretation can be made regarding factors important in the adjustment process and inter-relationships between factors. From a clinical perspective therefore, results indicate that effective low vision rehabilitation should include programs that incorporate both psychosocial adjustment and functional adjustment services. Future research is recommended to develop new measures of psychosocial adjustment to age-related vision loss.

The presence of cognitive deficits in obstructive sleep apnea (OSA) is well-documented. Specifically, short- and long-term memory, attention/vigilance, and executive function (e.g. processing speed, mental flexibility, and problem solving) are affected. Cognitive deficits in aging occur in similar areas (i.e., memory and processing speed). Given that a greater percentage of older adults experience sleep-disordered breathing as compared to middle-aged adults, it is possible that OSA may account for some of the deficits typically attributed to aging. This study investigated this hypothesis by comparing middle-aged and older adults with and without OSA on computer-based measures of cognitive performance. No effect of OSA or an interaction between OSA and age on cognitive function was found; an effect of age on processing speed, distinguishing stimuli rapidly, attention, spatial ability/mental flexibility, and both working memory and short-term visual memory was found. This study also explored whether or not cognitive function may be improved in persons with OSA by re-assessing those participants one month after treatment. An effect of treatment on improvements on processing speed, distinguishing stimuli rapidly, mental flexibility, and short term memory was found. Overall, findings reflect the ability of treatment to improve cognitive function among OSA patients, regardless of lack of deficits when compared to those without OSA.

Thesis (M.A.) University of Missouri-Columbia, 2005.
The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (July 10, 2006) Includes bibliographical references.

Thesis (B.Sc)--University of Hong Kong, 1999.
"A dissertation submitted in partial fulfilment of the requirements for the Bachelor of Science (Speech and Hearing Sciences), The University of Hong Kong, May 14, 1999." Also available in print.

Thesis (Ph. D.)--University of Alabama at Birmingham, 2008.
Title from PDF title page (viewed Sept. 23, 2009). Additional advisors: Karlene K. Ball, H. Randall Griffith, Daniel C. Marson, Sylvie Mrug, David E. Vance. Includes bibliographical references (p. 59-80).

Background: Prior studies regarding the risk factors of mild cognitive impairment (MCI), such as physical activity (PA) and sleep related factors in older Chinese populations are scarce, and the findings have not been consistent. Objectives: 1. To cross-sectionally and longitudinally examine the dose-response association between PA and cognitive function by Delayed Word Recall Test (DWRT) or Mini-mental State Examination (MMSE). 2. To cross-sectionally and prospectively examine the association of sleep related factors, including sleep duration, daytime napping, morning tiredness and insomnia, with cognitive function. Design: Cross-sectional and longitudinal analysis using both baseline and follow-up data from the GBCS. Methods Baseline data from 8,451 men and 22,067 women aged 50 years or above were used for the cross-sectional analysis. Among them, 4,214 men and 11,284 women participating in the second examination were included in the longitudinal analysis. Information on demographic, socioeconomic and lifestyle factors, and personal disease history was collected. Cognitive function was assessed by MMSE and DWRT under standardized protocols. Results 1. Significant dose-response relations across quintiles of metabolic equivalent value (METs) with DWRT score in participants with or without good self-rated health were found in cross-sectional analysis (all P for trend <0.001). 2. Prospectively, compared to those who were physically active, those with moderate activity or inactivity had increased risk for MCI. Regarding daily walking time, subjects with walking of 0.5 to 1 h, or ≥1 h had significantly reduced risk of MCI by 25% and 31% respectively compared with those who walked < 0.5 h per day. Subjects with low PA level at both baseline and follow-up had a significantly higher risk of MCI than those reporting PA at both baseline and follow-up. 3. Cross-sectionally, after adjustment for a range of potential confounders, an inverted U-shaped association between sleep duration and DWRT score was found, with 7 to 8 h of habitual sleep duration showing the highest score (P-values for trend from 3 to 7 h and from 7 to ≥10 h were all ≤0.001). Subjects with daily napping, morning tiredness, or insomnia had lower DWRT score than those without (P ranged from <0.001 to 0.01). 4. Prospectively, after adjustment for multiple risk factors, compared to sleep duration of 7 hours per day, those with sleep duration of 5 hours or less had increased risk for MCI by 43%. The adjusted P value for the linear trend from sleep duration of 3 hours to 7 hours per day was 0.01. The association remained after excluding those with poor health status. No significant associations of daytime napping, morning tiredness and insomnia with MCI were found. Conclusions In summary, we found a significant dose response association between PA and cognitive function in both cross-sectional and longitudinal analysis. One hour of daily walking is recommended for older Chinese people to delay or prevent cognitive decline. Short or long sleep duration may also be an important predictor of mild cognitive impairment. Sleep duration of less than 6 hours per day may indicate an increase risk of cognitive impairment in older people.
published_or_final_version
Community Medicine
Doctoral
Doctor of Philosophy

China has 9 million elderly individuals with dementia, which places it first in the world. Although family care remains the major source of support for people with dementia, residential care has become an indispensable choice in recent years. The biggest concern is the quality of life of the elderly with cognitive impairment or dementia (QOL-ECI) in residential care facilities (RCFs). Previous studies have explored many individual-level factors associated with QOL-ECI; however, less discussion has been conducted on how to improve it from an organizational-level perspective. China serves as a good research setting for this issue. The present study aims to establish an organizational-level framework to investigate QOL-ECI in RCFs. The Person-centered Care (PCC) Approach serves as an organizational strategy, and the High Commitment Work System (HCWS) is used as a human resource management practice. The study exposes the QOL-ECI status of RCFs in Xi’an China; and examines the relationship between PCC/HCWS and QOL-ECI respectively and jointly. A quantitative research method, survey in particular has been designed to achieve the research objectives, and has been conducted in two phases. Phase one of the study aims to validate a Chinese Version of the Person-centered care Assessment Tool (P-CATC), which is designed to measure the extent to which formal caregivers rate their facility as being person-centered. The resulting 24-item P-CAT-C is validated among a sample of full-time employees (n=330) in all 34 RCFs in urban Xi’an, a city in China. Phase two is a survey conducted among the same 34 RCFs. Full-time employees (n=330) evaluated the HCWS level for each RCF; residents with cognitive impairment (n=307) and their respective personal care workers (n=207) were invited to evaluate QOL-ECI. Hierarchical Linear Modeling (HLM) has been adopted to test the hypothesis. In phase one study, Confirmatory Factor Analysis (CFA) shows that a three-factor 15-item solution of the P-CAT-C provided adequate fit indices to the data (χ2 = 145.69, df = 81, p< 0.001, CFI = 0.93, TLI=0.91; RMSEA = 0.05). The internal consistency coefficient (Cronbach’s α=0.68) is satisfactory. The inter scale correlation shows good construct validity. The result of Phase two study shows that the total mean patient-rated QOL-ECI score is 36.06 (SD=8.16) and the caregiver-rated score is 34.09 (SD=6.88). Using caregiver-rated QOL-ECI as the dependent variable, the HLM regression analysis shows that PCC and HCWS are statistically significant with QOL-ECI respectively, and that the HCWS has a positive moderate effect on the relationship between PCC and QOL-ECI. Using patient-rated QOL-ECI as the dependent variable, the hypotheses are partially supported. This study is among the first to report the QOL-ECI status of RCFs in China. It initially demonstrates that PCC and HCWS are positively associated with QOL-ECI both respectively and jointly. It also primarily establishes an organizational-level framework to examine QOL-ECI. This will generate valuable implications and insight into research, practice and policy-making. Finally, this study further develops the PCC theory from an organizational perspective, and contributes to both management and social work literature by first adopting the HCWS for service organizations for the elderly.
published_or_final_version
Social Work and Social Administration
Doctoral
Doctor of Philosophy

Purpose To assess the relationship between corrected refractive errors and the degree of visual impairment, and determine the prevalence of myopic retinopathy and tilted discs in subjects attending the Blue Mountains Eye Study. Methods The Blue Mountains Eye Study is a population—based cohort of urban Australians aged 49 or older. Of the 4433 eligible persons, 3654 (82.4%) participated in the study between 1992—4 (BMES I). Of the 3114 living eligible participants from BMES I, 2334 (75.0%) were reexamined between 1997—9 (BMES H). The ocular examination included logMAR visual acuity, standardised refraction, applanation tonometry, cover testing, stereoscopic retinal photographs and Humphrey visual field testing. Retinal signs adjudicated included posterior staphyloma, lacquer cracks, Fuchs’ spot, myopic chorioretinal thinning and atrophy, Bperipapillary atrophy and tilted optic discs. Visual impairment was defined as best-corrected visual acuity of 20/40 or worse.

The older adult population in the United States is rapidly expanding both because of longer life expectancies as well as the aging of the baby boomers. While vision impairment is a growing concern among older adults, there have been few, mostly small studies, of the impact of vision impairment on this population. The present study uses a national data set, the Second Supplement on Aging (1994 -1996) from the National Health Interview Survey, in a cross-sectional study of 9,447 civilian non-institutionalized persons, aged 70 years and over at the time of their interview. The SOA II has been studied in the context of a social theory of aging that emphasizes interdependence through the life course using a stress process model that has been refined into a disability model. Disability is understood as a social construction outcome rather than as a medical outcome. Vision impairment is the stressor which is mediated by health (falls, functioning and self-health report), financial resources (education, income and having only public health insurance) and social support (marital, living along, having no living children, social activities in number and intensity). Depression is a possible, but not a necessary result of vision impairment. Disability may result when a medical pathology leads to an impairment which results in a functional limitation and finally a social disability. This secondary analysis used a multinomial logistic regression for both the whole sample as well as separately for each gender. For the whole sample the results indicate that a typical profile of a vision-impaired older adult depressed some/all of the time, would be a younger-old White woman (aged 70-74 years old) who has fallen in the past 12 months, has difficult with one or more Activities of Daily Living or with both one or more Activities of Daily Living and Instrumental Activities of Daily Living, has a poor to fair self-heath report, a family income under $20,000, a high school or less education, lives alone, has a living child and lacks social activities in number and intensity. In the gender samples, only the female sample at the some/all of the time depression category is significant. Older vision-impaired adults, especially older women who have more social supports are less likely to be depressed and so disabled. There is a need for social policies that will educate, encourage and support older vision-impaired adults as they seek to compensate for the loss of vision, often late in life.

[Truncated abstract] The aim of the present series of studies was to identify barriers to working memory for multifeature visuospatial stimuli in normal aging. Memory for multifeature stimuli requires retention of multiple visuospatial features, as well as the relationships between features within stimuli, known as memory binding. In Experiment 1, younger people (17-25 years) and older people (66-95 years) completed a modification of Wheeler and Treisman’s (2002) visual change detection task, to determine the effects of normal aging on memory binding, and memory for multiple features ... Results indicated that older people did not have a memory binding decrement compared to younger people. Further, younger people performed more accurately when cued to attend to a specific feature, while older people’s performance did not improve with cueing ... Experiment 2 employed the binding condition and the ‘either’ condition, with stimuli presented either sequentially or simultaneously. Results were consistent with Experiment 1, with no age-related binding decrement, regardless of the method of stimulus presentation. In Experiment 1, older people demonstrated a shape memory decrement compared to younger people. Experiments 3A and 3B were performed to determine whether this result did represent a memory decrement per se, or whether it was a consequence of a shape perception decrement ... Compared to younger people, older people demonstrated a similar performance decrement across shape perception and memory tasks, indicating that their performance was mediated by an underlying perceptual decrement. Experiment 4 was conducted to determine if older people had difficulty selectively attending to a feature across multifeature stimuli, as suggested by their failure to benefit from cueing in Experiment 1 ... Older people had a greater performance decrement when the irrelevant feature was incompatible with the correct response, compared to younger people, consistent with a selective attention decrement. Experiment 5B adapted the design of Experiment 4 to both a perception task and a working memory task, while Experiment 5A identified appropriate stimulus features to use in Experiment 5B ... Overall, older people do not have particular difficulty remembering multiple visuospatial features, or binding these features within working memory. Rather, older people’s performance was marked by difficulty selectively attending to a specified feature across multifeature stimuli.