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The present study expanded the story recognition and inference literature by investigating age differences within the older age range, differences as a result of mild cognitive impairment (MCI), and extending the focus of the investigation into the consistency of responding. 304 older adults completed a story recognition task across five different occasions. Old-old (00) adults and those with more severe MCI showed poorer ability to accurately recognize inferences, and less sensitivity to discriminate between statement types. Intraindividual variability was positively correlated with increasing age and cognitive impairment, and interactions revealed the greatest inconsistency involved the false, rather than inferred statements. The findings support our proposal that participants used two different recognition strategies, and their episodic memory ability defined the efficiency and frequency of use of the strategies. 00 and MCI adults may be less able to recognize that something plausible and consistent with an event may not have actually occurred.

Current classification systems for identifying individuals at the earliest stages of dementia, based primarily on cognitive measures, may be limited in scope. The present study examined physical functioning in a sample of 304 nondemented, older adults, classified based on presence and severity of mild cognitive impairment. In general, lower levels of physical functioning and greater inconsistency in physical functioning were found in older participants and in participants with increasing severity of cognitive impairment. Evaluation of the combined and unique contributions of level of and inconsistency in physical functioning to predicting cognitive status group membership revealed that, for some physical measures, inconsistency in physical functioning provided unique information beyond level of performance. These results are consistent with the notion that inconsistency in performance may be a behavioural marker of compromised neurological functioning and that information regarding physical functioning may prove useful for identifying individuals at the earliest stages of dementia.

Thesis (M. Med. Sc.)--University of Hong Kong, 2006.

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 (M. Med. Sc.)--University of Hong Kong, 2005.

A cross-sectional, retrospective study, using data from the Victoria Longitudinal Study, was conducted to investigate the impact of impending death on test performance on the Mini-Mental State Examination (MMSE), a measure of general cognitive functioning. Test score on the MMSE of individuals collected between one to five years before death was compared to the MMSE test score of individuals who are still alive. Results revealed a significant difference between the MMSE total score of individuals who died within three years post-measurement and survivors, and those who died between three to five years after measurement. When the individual items were analyzed, only the "WORLD" and "copy pentagon" items obtained results similar to the total score, providing support for the specificity of impending death effect on fluid abilities. The cause of death (CardioKerebro-vascular disease and non-CardioICerebro-vascular disease), however, did not differentiate the groups, suggesting that the mechanism of impending death may not be disease-related. Our results revealed that the influence of impending death on cognitive functioning could be observed on the MMSE; the source of the influence is still unknown, however. Despite the statistical significance, our findings did not appear to be clinically meaningful. As a result, our findings suggest that it may not be necessary to collect new normative data that are removed of the effects of impending death.

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

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