Chaoke Liang

Late Life Leisure Activities and Risk of Cognitive Decline

BACKGROUND Studies concerning the effect of different types of leisure activities on various cognitive domains are limited. This study tests the hypothesis that mental, physical, and social activities have a domain-specific protection against cognitive decline. METHODS A cohort of a geographically defined population in China was examined in 2003-2005 and followed for an average of 2.4 years. Leisure activities were assessed in 1,463 adults aged 65 years and older without cognitive or physical impairment at baseline, and their cognitive performances were tested at baseline and follow-up examinations. RESULTS High level of mental activity was related to less decline in global cognition (β = -.23, p < .01), language (β = -.11, p < .05), and executive function (β = -.13, p < .05) in ANCOVA models adjusting for age, gender, education, history of stroke, body mass index, Apolipoprotein E genotype, and baseline cognition. High level of physical activity was related to less decline in episodic memory (β = -.08, p < .05) and language (β = -.15, p < .01). High level of social activity was associated with less decline in global cognition (β = -.11, p < .05). Further, a dose-response pattern was observed: although participants who did not engage in any of the three activities experienced a significant global cognitive decline, those who engaged in any one of the activities maintained their cognition, and those who engaged in two or three activities improved their cognition. The same pattern was observed in men and in women. CONCLUSIONS Leisure activities in old age may protect against cognitive decline for both women and men, and different types of activities seem to benefit different cognitive domains.

Effect of Long-Term Exposure to Fluoride in Drinking Water on Risks of Bone Fractures

Findings on the risk of bone fractures associated with long‐term fluoride exposure from drinking water have been contradictory. The purpose of this study was to determine the prevalence of bone fracture, including hip fracture, in six Chinese populations with water fluoride concentrations ranging from 0.25 to 7.97 parts per million (ppm). A total of 8266 male and female subjects ≥50 years of age were enrolled. Parameters evaluated included fluoride exposure, prevalence of bone fractures, demographics, medical history, physical activity, cigarette smoking, and alcohol consumption. The results confirmed that drinking water was the only major source of fluoride exposure in the study populations. A U‐shaped pattern was detected for the relationship between the prevalence of bone fracture and water fluoride level. The prevalence of overall bone fracture was lowest in the population of 1.00‐1.06 ppm fluoride in drinking water, which was significantly lower (p < 0.05) than that of the groups exposed to water fluoride levels ≥4.32 and ≤0.34 ppm. The prevalence of hip fractures was highest in the group with the highest water fluoride (4.32‐7.97 ppm). The value is significantly higher than the population with 1.00‐1.06 ppm water fluoride, which had the lowest prevalence rate. It is concluded that long‐term fluoride exposure from drinking water containing ≥4.32 ppm increases the risk of overall fractures as well as hip fractures. Water fluoride levels at 1.00‐1.06 ppm decrease the risk of overall fractures relative to negligible fluoride in water; however, there does not appear to be similar protective benefits for the risk of hip fractures.

Correlates of depressive symptoms in rural elderly Chinese

Late life depression has been studied in many populations around the world. However, findings on risk factors for late life depression have remained inconsistent.

Selenium level and depressive symptoms in a rural elderly Chinese cohort

BackgroundSelenium is considered a protective agent against free radicals through the maintenance of better enzyme activity. The few studies examining the relationship between selenium and depression have yielded inconsistent results and none of these studies considered the role of cognitive function in this context.MethodsA cross-sectional evaluation of 1737 rural Chinese age 65 and over from two provinces in China was conducted. Depressive symptoms were assessed using the Geriatric Depression Scale (GDS). Cognitive function was assessed using various cognitive instruments. Selenium measures were obtained from nail samples. Other information collected included demographic characteristics and medical history. Analysis of covariance models were used to identify factors associated with GDS score.ResultsHigher selenium levels were associated with lower GDS scores adjusting for demographic and medical conditions (p = 0.0321). However, the association between selenium and depressive symptoms was no longer significant when cognitive function score was adjusted in the model (p = 0.2143).ConclusionsHigher selenium level was associated with lower depressive symptoms without adjusting for cognition in this cohort. However, after cognition was adjusted in the model the association between selenium and depressive symptoms was no longer significant, suggesting that selenium’s association with depressive symptoms may be primarily through its association with cognitive function.

Hypertension and Cognitive Decline in Rural Elderly Chinese

OBJECTIVES: To examine the association between hypertension and cognitive decline in older adults.

Selenium level is associated with apoE ε4 in rural elderly Chinese

OBJECTIVE Se is an essential trace element in human nutrition associated with antioxidant activity. Previous studies on predictors of toenail Se or serum Se have mostly concentrated on demographic factors such as age and gender. The present paper examines the association between apoE genotype and Se levels in nail samples in a rural elderly Chinese cohort. DESIGN Two thousand Chinese aged 65 years and over from four counties in China were enrolled in a cohort to study the association of Se with cognitive decline. Nail samples were collected from each participant and analysed for Se levels. Dietary Se intake was estimated from an FFQ using Se contents measured in food items collected from each village. Blood samples on filter cards were collected and analysed for apoE genotype. Mixed-effect models were constructed with nail Se level as the dependent variable and each village as the random effect, which controlled for the potential confounding effect from correlation in Se measures obtained from participants residing in the same village. RESULTS In this elderly Chinese cohort, carriers of the apoE epsilon4 allele had significantly lower Se levels measured in nail samples than non-carriers after adjusting for other significant covariates and controlling for estimated dietary Se intake. There was no significant difference between the two genotypes on estimated Se dietary intake (P = 0.6451). CONCLUSIONS Future studies are needed to examine the mechanism underlying the association between the apoE epsilon4 allele and Se levels, including the role of oxidative stress and that of reduced lipid metabolism in the apoE epsilon4 carriers.

Normative Data for Neuropsychological Tests in a Rural Elderly Chinese Cohort

Normative information is important for appropriate interpretation of cognitive test scores as a critical component of dementia diagnosis in the elderly population. A cross-sectional evaluation of 1826 participants aged 65 years and older from four rural counties in China was conducted using six cognitive instruments including tests of global cognitive function (the Community Screening Instrument for Dementia), memory (Word List Learning and Recall tasks from the Consortium to Establish a Registry for Alzheimers Disease, IU Story), language (Animal Fluency Test), and executive function (IU Token). Multiple regression models adjusting for demographic variables were used to provide standardized residuals z-scores and corresponding percentile ranking for each cognitive test. In all cognitive tests older age was associated with worse test performance while exposure to education was related to better cognitive test performance. We also detected a significant gender difference with men scoring better than women and a significant gender by education interaction on two tests. The interaction indicates that gender difference in test scores was much smaller in participants with more education than those who had less or no education. These demographically adjusted, regression-based norms can be a useful tool to clinicians involved with differential diagnosis of cognitive and memory disorders in older adults in rural China.

The association between selenium and lipid levels: A longitudinal study in rural elderly Chinese

OBJECTIVE A protective effect of selenium on lipid levels has been reported in populations with relatively low selenium status. However, recent studies found that high selenium exposure may lead to adverse cardiometabolic effects, particularly in selenium-replete populations. We examined the associations of selenium status with changes in lipid levels in a 7-year follow up of an elderly Chinese cohort including participants from selenium-deplete areas. METHODS Study population consisted of 140 elderly Chinese aged 65 or older with nail selenium levels measured at baseline (2003-2005). Lipid concentrations were measured in fasting blood samples collected at baseline and the 7-year follow-up (2010-2012). Analysis of covariance (ANCOVA) models was used to determine the association between baseline selenium status and changes in lipid levels from baseline to follow-up adjusting for other covariates. RESULTS Mean (±standard deviation) baseline selenium concentration was 0.41±0.2mg/kg. In prospective analysis, we found that individuals in the highest selenium quartile group showed 1.11 SD decrease on total-cholesterol (p<0.001), 0.41 SD increase on HDL-cholesterol (p<0.001) and 0.52 SD decrease on triglyceride after 7 years than those in the lowest selenium quartile group. The similar trends were seen with significant lipid changes in the 2nd and 3rd quartile groups. CONCLUSION Selenium has modest beneficial effects on blood lipid levels in a population with relatively low selenium status. Our result suggests adequate dietary selenium intake as a potential prevention strategy for lowering lipid levels in selenium deplete populations.

Leisure activities and cognitive decline in a rural elderly Chinese cohort

African American females. 347 were aMCI (20.2%) and were diagnosed according to updated Petersen criteria (objective memory impairment, subjective complaints and absence of functional decline without dementia). Cox regression models were examined using mortality as the outcome and aMCI as the time-dependent covariate for nondemented individuals at baseline. Models were stratified to adjust for race and gender, and the common HR across strata is reported. Age was used as the time scale. Results: The overall death rate in this sample is 8.97%. Cox proportional hazard model stratified by sex and race shows that aMCI is a significant risk factor for mortality with a hazard ratio (HR) of 2.21 (p < .0002). When stratified by race, the HR was 2.48 for African Americans (p 1⁄4 .093) and 2.16 (p 1⁄4 .0008) for Caucasians. Stratification by sex shows HRs of 1.62 (p 1⁄4 .13) for males and 3.00 (p 1⁄4 .0001) for females. The interaction effects between race and gender were not significant. Conclusions: aMCI is a risk factor for all cause mortality in elderly individuals. It appears to be a stronger risk factor among females. Underlying co-morbidities may explain the gender difference. Additional follow-up will be required to confirm the observed differences by race and sex.