Higher dementia incidence in older adults with type 2 diabetes and large reduction in HbA1c.

BACKGROUND: although type 2 diabetes increases risk of dementia by 2-fold, whether optimizing glycemic level in late life can reduce risk of dementia remains uncertain. We examined if achieving the glycemic goal recommended by the American Diabetes Association (ADA) within a year was associated with lower risk of dementia in 6 years. METHODS: in this population-based observational study, we examined 2246 community-living dementia-free Chinese older adults with type 2 diabetes who attended the Elderly Health Centres in Hong Kong at baseline and followed their HbA1c level and cognitive status for 6 years. In line with the ADA recommendation, we defined the glycemic goal as HbA1c < 7.5%. The study outcome was incident dementia in 6 years, diagnosed according to the 10th revision of the International Statistical Classification of Diseases and Related Health Problems (ICD-10) or Clinical Dementia Rating of 1-3. RESULTS: those with HbA1c ≥ 7.5% at baseline and HbA1c < 7.5% in 1 year were associated with higher rather than lower incidence of dementia, independent of severe hypoglycemia, glycemic variability and other health factors. Sensitivity analyses showed that a relative reduction of ≥10%, but not 5-10%, in HbA1c within a year was associated with higher incidence of dementia in those with high (≥8%) and moderate (6.5-7.9%) HbA1c at baseline. CONCLUSION: a large reduction in HbA1c could be a potential predictor and possibly a risk factor for dementia in older adults with type 2 diabetes. Our findings suggest that optimizing or intensifying glycemic control in this population requires caution.

Lower risk of incident dementia among Chinese older adults having three servings of vegetables and two servings of fruits a day.

Background: dietary modification can potentially reduce dementia risk, but the importance of fruits and the amount of vegetables and fruits required for cognitive maintenance are uncertain. We examined whether the minimal daily requirement of vegetables and fruits recommended by the World Health Organization (WHO) would independently lower dementia risk. Methods: in this population-based observational study, we examined the diet of 17,700 community-living dementia-free Chinese older adults who attended the Elderly Health Centres in Hong Kong at baseline and followed their cognitive status for 6 years. In line with the WHO recommendation, we defined the cutoff for minimal intake of vegetables and fruits as at least three and two servings per day, respectively. The study outcome was incident dementia in 6 years. Dementia was defined by presence of clinical dementia in accordance with the 10th revision of the International Statistical Classification of Diseases and Related Health Problems (ICD-10) or Clinical Dementia Rating of 1-3. Results: multivariable logistic regression analysis showed that the estimated odds ratios for incident dementia were 0.88 (95% confidence interval 0.73-1.06; P = 0.17) for those consuming at least three servings of vegetables per day, 0.86 (0.74-0.99; P < 0.05) for those consuming at least two servings of fruits per day and 0.75 (0.60-0.95; P = 0.02) for those consuming at least these amounts of both at baseline, after adjusting for age, gender, education, major chronic diseases, physical exercise and smoking. Conclusion: having at least three servings of vegetables and two servings of fruits daily might help prevent dementia in older adults.

Late-life longitudinal blood pressure trajectories as predictor of dementia.

While hypertension is widely recognized as a risk factor for dementia, few observational studies and clinical trials fully accounted for the effect of age on blood pressure (BP) changes prior to dementia onset. In this territory-wide population-based longitudinal study of 16,591 community-living dementia-free older adults, we followed their BP and cognitive status and tested if loss of longitudinal increase in BP in late life was associated with higher dementia risk in 6 years, with consideration of the confounding effects of hypertension, hypotension, BP variability, and other health problems and behaviours and, in the data analysis, exclusion of individuals who developed dementia within 3 years after baseline to minimize risk of reverse causality. Over 72,997 person-years of follow-up, 1429 participants developed dementia. We found that loss of longitudinal increase in systolic BP (defined as SBP increased by either < 10 mmHg or 10%) from baseline to Year 3 was independently associated with higher risk of incident dementia at Years 4 to 6 (adjusted OR 1.22, 95% CI 1.02-1.45, p = 0.03; adjusted OR 1.24, 95% CI 1.03-1.50, p = 0.02; respectively). Our findings suggest that late-life SBP trajectory changes might independently predict dementia onset and highlight the importance of including longitudinal BP monitoring in dementia risk assessment.

Dementia and risk of visual impairment in Chinese older adults.

We had previously identified visual impairment increasing risk of incident dementia. While a bi-directional vision-cognition association has subsequently been proposed, no study has specifically examined the longitudinal association between dementia and incidence of clinically defined visual impairment. In this territory-wide community cohort study of 10,806 visually unimpaired older adults, we examined their visual acuity annually for 6 years and tested if dementia at baseline was independently associated with higher risk of incident visual impairment (LogMAR ≥ 0.50 in the better eye despite best correction, which is equivalent to moderate visual impairment according to the World Health Organization definition). By the end of Year 6, a total of 3151 (29.2%) participants developed visual impairment. However, we did not find baseline dementia associating with higher risk of incident visual impairment, after controlling for baseline visual acuity, cataract, glaucoma, diabetes, hypertension, hypercholesterolemia, heart diseases, stroke, Parkinson's disease, depression, hearing and physical impairments, physical, intellectual and social activities, diet, smoking, age, sex, educational level, and socioeconomic status. Among different covariables, baseline visual acuity appears to be more important than dementia in contributing to the development of visual impairment. Our present findings highlight the need for re-evaluating whether dementia is indeed a risk factor for visual impairment.

Risk of incident dementia varies with different onset and courses of depression.

BACKGROUND: This study aims to examine if risk of dementia differs between adult- and late-onset depression. METHODS: 16,608 community-living dementia-free older adults were followed for 6 years to the outcome of incident dementia. Depression was diagnosed according to international diagnostic guidelines. Depression in adulthood or late life was categorized using age 65 as cutoff. Hazard ratio for dementia was estimated using Cox regression analysis. RESULTS: People with depression in adulthood only did not have higher dementia incidence, suggesting those in remission from adult-onset depression are not at greater risk of dementia. Conversely, having depression in both adulthood and late life was associated with higher dementia risk, and improvement in depression in late life was associated with lower risk, suggesting persistent or recurrent lifetime depression is a risk factor for dementia. Those with depression in late life only were not associated with higher dementia risk after controlling for the longitudinal changes in depressive symptoms, consistent with late-onset depression being a prodrome of dementia. LIMITATIONS: Reverse causation is a potential limitation. This was minimized by careful ascertainment of depression and dementia cases, exclusion of individuals with suspected dementia at baseline and those who developed dementia within 3 years after baseline, and controlling for various important confounders. CONCLUSIONS: Risk of incident dementia varies with presence and resolution of depression at different ages. Further studies are needed to test whether treating adult-onset depression may prevent dementia. Older adults with a history of depression present for an extended time should be monitored for cognitive decline.

Combined clinical and cognitive criteria to identify mild cognitive impairment in a southern Chinese community.

Mild Cognitive Impairment (MCI) is a recognized risk condition for clinical dementia. This paper attempted to explore the applicability of a combined cognitive and clinical approach to identify older Chinese adults at-risk of cognitive decline. Seven hundred forty randomly recruited community dwelling participants (aged 60 or over) were assessed at baseline and 2 years with Clinical Dementia Rating (CDR) and a cognitive battery. Baseline MCI groups were categorized by CDR-MCI, cognitive function (Cog-MCI), and a combined CDR-Cog approach. The cognitive approach adopted the Mayo clinic criteria. For the combined approach, nonamnestic MCI combined CDR 0.5 plus nonmemory cognitive deficits. The overall concordance between CDR and Cognitive test ratings were 65.3% (χ2 = 256.4, P<0.001, κ=0.44). With a combined approach, 424 (57%) participants were classified as normal. CDR-MCI group had higher cognitive scores compared with MCI groups by other criteria (1 way analysis of variance or ANOVA). At 2 years, the combined CDR-Cog MCI group identified all dementia (N=24) converters although group differences were not significant. Cognitive function and CDR identified participants potentially at-risk for furthermore decline, but exhibited some differences in detection profiles. A combined approach may be more practical in screening for MCI participants with diverse educational and cultural background.

Higher Dementia Incidence in Older Adults with Poor Visual Acuity.

BACKGROUND: Longitudinal evidence of poor visual acuity associating with higher risk of incident dementia is mixed. This study aimed to examine if poor visual acuity was associated with higher dementia incidence in a large community cohort of older adults, independent of the possible biases relating to misclassification error, reverse causality, and confounding effects due to health problems and behaviors. METHODS: A total of 15,576 community-living older adults without dementia at baseline were followed for 6 years to the outcome of incident dementia, which was diagnosed according to the ICD-10 or a Clinical Dementia Rating of 1 to 3. Visual acuity was assessed using the Snellen's chart at baseline and follow-up. Important variables including demographics (age, sex, education, and socioeconomic status), physical and psychiatric comorbidities (cardiovascular risks, ophthalmological conditions, hearing impairment, poor mobility, and depression), and lifestyle behaviors (smoking, diet, physical, intellectual, and social activities) were also assessed. RESULTS: Over 68,904 person-years of follow-up, 1,349 participants developed dementia. Poorer visual acuity at baseline was associated with higher dementia incidence in 6 years, even after adjusting for demographics, health problems, and lifestyle behaviors, and excluding those who developed dementia within 3 years after baseline. Compared with normal vision, the hazard ratio of dementia was 1.19 (p = .31), 2.09 (p < .001), and 8.66 (p < .001) for mild, moderate, and severe visual impairment, respectively. CONCLUSIONS: Moderate-to-severe visual impairment could be a potential predictor and possibly a risk factor for dementia. From a clinical perspective, older adults with poor visual acuity might warrant further risk assessment for dementia.

Use of clinical dementia rating in detecting early cognitive deficits in a community-based sample of Chinese older persons in Hong Kong.

With increasing demand for dementia care in the Chinese community, there is a pressing need to identify practical and valid assessment tool for early detection of dementia. In a sample of 473 randomly recruited community-dwelling Chinese older persons aged 60 or above, we evaluated the cognitive characteristics of subjects with Clinical Dementia Rating (CDR) of 0.5. The cognitive profiles of CDR 0.5 subjects were compared with standard clinical criteria for mild cognitive impairment. The Alzheimer's disease assessment scale-cognitive subscale and list learning delay recall test scores were between -1 and -2 SD below the cutoff for clinically not-demented subjects (CDR 0). Concordance between CDR 0.5 and mild cognitive impairment classifications were related to educational level of the subjects. A higher agreement was found in subjects having >6 years of education than subjects having

Association of Daily Intellectual Activities With Lower Risk of Incident Dementia Among Older Chinese Adults.

Importance: Associations between late-life participation in intellectual activities and decreased odds of developing dementia have been reported. However, reverse causality and confounding effects due to other health behaviors or problems have not been adequately addressed. Objective: To examine whether late-life participation in intellectual activities is associated with a lower risk of incident dementia years later, independent of other lifestyle and health-related factors. Design, Setting, and Participants: A longitudinal observational study was conducted at all Elderly Health Centres of the Department of Health of the Government of Hong Kong among 15 582 community-living Chinese individuals age 65 years or older at baseline who were free of dementia, with baseline evaluations performed January 1 to June 30, 2005, and follow-up assessments performed from January 1, 2006, to December 31, 2012. Statistical analysis was performed from January 1, 2015, to December 31, 2016. Main Outcomes and Measures: The main outcome was incident dementia as diagnosed by geriatric psychiatrists in accordance with the International Statistical Classification of Diseases and Related Health Problems, Tenth Revision, or a Clinical Dementia Rating of 1 to 3. At baseline and follow-up interviews, self-reported information on participation in intellectual activities within 1 month before assessment was collected. Examples of intellectual activities, which were described by a local validated classification system, were reading books, newspapers, or magazines; playing board games, Mahjong, or card games; and betting on horse racing. Other important variables including demographics (age, sex, and educational level), physical and psychiatric comorbidities (cardiovascular risks, depression, visual and hearing impairments, and poor mobility), and lifestyle factors (physical exercise, adequate fruit and vegetable intake, smoking, and recreational and social activities) were also assessed. Results: Of the 15 582 individuals in the study, 9950 (63.9%) were women, and the median age at baseline was 74 years (interquartile range, 71-77 years). A total of 1349 individuals (8.7%) developed dementia during a median follow-up period of 5.0 years. Multivariable logistic regression analysis showed that the estimated odds ratio for incident dementia was 0.71 (95% CI, 0.60-0.84; P < .001) for those with intellectual activities at baseline, after excluding those who developed dementia within 3 years after baseline and adjusting for health behaviors, physical and psychiatric comorbidities, and sociodemographic factors. Conclusions and Relevance: Active participation in intellectual activities, even in late life, might help delay or prevent dementia in older adults.

Intensity and Types of Physical Exercise in Relation to Dementia Risk Reduction in Community-Living Older Adults.

OBJECTIVE: To systematically examine the amount and type of physical exercise that might reduce the future risk of dementia in community-living older people. DESIGN: Six-year observational study. SETTING: All the Elderly Health Centers (EHCs) of the Department of Health in Hong Kong. PARTICIPANTS: A total of 15,589 community-living Chinese aged 65 years and older with no history of stroke, clinical dementia, or Parkinson disease when they completed health assessment at the EHCs in the first 6 months of 2005. MEASUREMENTS: Self-reported habitual physical exercise patterns, including the frequency, duration, and type of exercise, at baseline and Year 3 were analyzed. The study outcome was incident dementia in 6 years. Dementia was defined by presence of clinical dementia in accordance with the 10th revision of the International Statistical Classification of Diseases and Related Health Problems or Clinical Dementia Rating of 1 to 3. RESULTS: Both the cognitively stable and incident groups reported exercising a median of 7 days per week and 45 minutes per day at baseline and Year 3. The former practiced aerobic and mind-body exercises more at baseline and Year 3, whereas the latter practiced stretching and toning exercises more. The odds ratio for dementia remained significant for aerobic (0.81; 95% confidence interval 0.68-0.95; P = .01) and mind-body exercises (0.76; 0.63-0.92; P = .004) after excluding participants who developed dementia within 3 years after baseline and adjusting for important potential confounders, such as age, gender, educational level, and physical and psychiatric comorbidities. CONCLUSION: Although physical exercise is widely promoted as a nonpharmacological intervention for dementia prevention, not all types of exercise appear to be useful in reducing risk of dementia in older people. Our findings suggest that daily participation in aerobic and mind-body but not stretching and toning exercises might protect community-living older adults from developing dementia.