Sex Difference in the Relation Between Marital Status and Dementia Risk in Two Population-Based Cohorts

Marital Histories and Associations With Later-Life Dementia and Mild Cognitive Impairment Risk in the HUNT4 70+ Study in Norway

Objectives: Earlier studies suggest that being married in later life protects against dementia, and that being single in old age increases the risk of dementia. In this study, we examine midlife marital status trajectories and their association with dementia and mild cognitive impairment (MCI) at ages 70 plus using a large population based sample from Norway. Methods: Based on a general population sample linked to population registries (N = 8706), we used multinomial logistic regression to examine the associations between six types of marital trajectories (unmarried, continuously divorced, intermittently divorced, widowed, continuously married, intermittently married) between age 44 and 68 years from national registries and a clinical dementia or a MCI diagnosis after age 70. We estimated relative risk ratios (RRR) and used mediation analyses adjusting for education, number of children, smoking, hypertension, obesity, physical inactivity, diabetes, mental distress, and having no close friends in midlife. Inverse probability weighting and multiple imputations were applied. The population attributable fraction was estimated to assess the potential reduction in dementia cases due to marital histories. Results: Overall, 11.6% of the participants were diagnosed with dementia and 35.3% with MCI. Dementia prevalence was lowest among the continuously married (11.2%). Adjusting for confounders, the risk of dementia was higher for the unmarried (RRR = 1.73; 95% CI: 1.24, 2.40), continuously divorced (RRR = 1.66; 95% CI: 1.14, 2.43), and intermittently divorced (RRR = 1.50; 95% CI: 1.09, 2.06) compared to the continuously married. In general, marital trajectory was less associated with MCI than with dementia. In the counterfactual scenario, where all participants had the same risk of receiving a dementia diagnosis as the continuously married group, there would be 6.0% fewer dementia cases. Discussion: Our data confirm that staying married in midlife is associated with a lower risk of dementia and that divorced people account for a substantial share of dementia cases.

Regional disparities in Dementia-free Life Expectancy in Japan: An ecological study, using the Japanese long-term care insurance claims database

BACKGROUND

The number of people with dementia increases in an aging society; therefore, promoting policies for dementia throughout the community is crucial to creating a dementia-friendly society. Understanding the status of older adults with dementia in each region of Japan will be a helpful indicator. We calculated Dementia-free Life Expectancy and aimed to examine regional disparities and their associated factors.

METHODS

We calculated Dementia-free Life Expectancy and Life Expectancy with Dementia for each secondary medical area in Japan based on the Degree of Independence in Daily Living for the Demented Elderly, using data extracted from the Japanese long-term care insurance claims database. We then conducted a partial least squares regression analysis, the objective variables being Dementia-free Life Expectancy and Life Expectancy with Dementia for both sexes at age 65, and explanatory regional-level variables included demographic, socioeconomic, and healthcare resources variables.

RESULTS

The mean estimated regional-level Dementia-free Life Expectancy at age 65 was 17.33 years (95% confidence interval [CI] 17.27-17.38) for males and 20.05 years (95% CI 19.99-20.11) for females. Three latent components identified by partial least squares regression analysis represented urbanicity, socioeconomic conditions, and health services-related factors of the secondary medical areas. The second component explained the most variation in Dementia-free Life Expectancy of the three, indicating that higher socioeconomic status was associated with longer Dementia-free Life Expectancy.

CONCLUSIONS

There were regional disparities in secondary medical area level Dementia-free Life Expectancy. Our results suggest that socioeconomic conditions are more related to Dementia-free Life Expectancy than urbanicity and health services-related factors.

Sex-Differential Associations Between Body Mass Index and the Incidence of Dementia

BACKGROUND

Little is known about the sex differences in the association between body mass index (BMI) and dementia in late life.

OBJECTIVE

Therefore, this retrospective cohort study aimed to analyze associations between BMI and dementia in older women and men separately in general practices in Germany.

METHODS

This study included patients followed in one of 832 general practices in Germany between 2006 and 2019 (index date: first visit date). Study variables included dementia (dependent variable), BMI (independent variable), age, sex, and comorbidities (control variables). Kaplan-Meier curves and adjusted Cox regression analyses were conducted to analyze associations between BMI and the 10-year incidence of dementia in women and men, separately.

RESULTS

There were 296,767 patients included in this study (mean [standard deviation] age 70.2 [5.9] years; 54.3% women). The proportion of underweight, normal weight, overweight, and obesity was 0.9%, 25.5%, 41.5%, and 32.1%, respectively. The 10-year incidence of dementia significantly decreased with increasing BMI, from 11.5% in women with underweight to 9.1% in those with obesity (log-rank p <  0.001). Respective figures in men were 12.0% and 8.2% (log-rank p <  0.001). In women, only overweight (versus normal weight) was significantly associated with dementia (HR = 0.93, 95% CI = 0.88-0.97). In contrast, in men, the only BMI category significantly associated with the incidence of dementia was underweight (HR = 1.58, 95% CI = 1.11-2.25).

CONCLUSION

In this study conducted in Germany, overweight was negatively associated with dementia in women, whereas there was a positive underweight-dementia relationship in men. More data are needed to confirm or refute these findings in other settings.

Association Between Social Network and Cognitive Function: A Cross-Sectional Assessment From the Cardiovascular and Metabolic Diseases Etiology Research Center Cohort (2013-2018)

BACKGROUND

This study aimed to investigate how social networks are associated with cognitive function in the middle-aged and elderly Korean population.

METHODS

A total of 7,704 individuals over the age of 50 were included from the baseline recruitment of the Cardiovascular and Metabolic Diseases Etiology Research Center cohort from the years 2013 to 2018. Egocentric social network characteristics including network size, intimacy, and frequency of face-to-face meetings were measured as exposures, and the Korean version of Mini-Mental State Examination (K-MMSE) score was measured to reflect general cognitive function as an outcome. We also stratified the analysis by income level into tertiles, with income caps of 42,000 thousand won and 72,000 thousand won. A general linear regression model was used, adjusting for age, gender, socioeconomic factors, lifestyle factors, depressive symptoms, and study settings.

RESULTS

Social network properties were positively associated with cognitive function in both men and women. However, the specific estimates varied according to gender and income level. In men, frequency was most significantly associated with cognitive function (standardized β = 0.093, p-value <0 .0001). In women, the strength of the association with cognitive function was found in size (standardized β = 0.055, p-value = 0.001). The effect modification of income level could be seen in the association between frequency and cognitive function. The strongest association between frequency and cognitive function was found in the middle income group in men (standardized β = 0.114, p-value = 0.0063), and the low income group in women (standardized β = 0.076, p-value = 0.0039).

CONCLUSION

There were positive associations between social network properties (i.e., size, intimacy, and frequency of face-to-face meetings) and cognitive function. The degree of association varied according to social network properties, gender, and income level. Overall, among social network properties, social network size was an important factor in the cognition of women, whereas frequency was important in the cognition of men.