Sex differences in cognitive decline among middle-aged and older adults: a cohort study in Europe.

OBJECTIVES: Previous studies on sex differences in cognitive decline provide inconsistent findings, with many European countries being underrepresented. We determined the association between sex and cognitive decline in a sample of Europeans and explored differences across birth cohorts and regions. METHODS: Participants 50+ years old enrolled in the Survey of Health, Ageing and Retirement in Europe had their cognition measured by tests of immediate recall, delayed recall and verbal fluency biennially up to 17 years of follow-up (median 6, interquartile range 3-9 years). We used linear mixed-effects models to assess the relationship between sex and the rate of cognitive decline, adjusting for sociodemographic and health-related characteristics. RESULTS: Of 66,670 participants (mean baseline age 63.5 ± standard deviation 9.4), 55% were female. Males and females had similar rates of decline in the whole sample in immediate recall (beta for interaction sex × time B = 0.002, 95% CI -0.001 to 0.006), delayed recall (B = 0.000, 95% CI -0.004 to 0.004), and verbal fluency (B = 0.008, 95% CI -0.005 to 0.020). Females born before World War II had a faster rate of decline in immediate recall and delayed recall compared to males, while females born during or after World War II had a slower rate of decline in immediate recall. Females in Central and Eastern Europe had a slower rate of cognitive decline in delayed recall compared to males. DISCUSSION: Our study does not provide strong evidence of sex differences in cognitive decline among older Europeans. However, we identified heterogeneity across birth cohorts and regions.

Hearing loss, sick leave, and disability pension: findings from the HUNT follow-up study.

BACKGROUND: Evidence on the association between hearing loss and sick leave or disability pension is to a great extent based on few cross-sectional studies and remains unclear. We aim to assess the associations in a long-term follow-up population study. METHODS: We used baseline data from a large population-based hearing study in Norway, the HUNT Hearing study (1996-1998). The sample included 21 754 adults (48.5% men, mean age at baseline 36.6 years). We used register data on sick leave and disability pension (1996-2011). Cox regression was used to assess the association between hearing loss at baseline (Pure tone average/PTA 0.5-4 kHz > 20 dB) and time to first physician-certified sick leave episode, as well as time to first disability pension payment. RESULTS: Hearing loss at baseline (yes/no) was weakly associated with time to first physician-certified sick leave episode: Hazard ratio (HR) 1.2 (95% confidence interval (CI) 1.1-1.3). Restricting the exposed group to people with both hearing loss and tinnitus, the HR was slightly increased: 1.3 (95% CI 1.1-1.6). Hearing loss in 1996-1998 was also associated with time to first received disability pension: HR 1.5 (95% CI 1.3-1.8). Stronger associations were found for disabling hearing loss (PTA > 35). Restricting the exposure to hearing loss and tinnitus, the HR was increased: 2.0 (95% CI 1.4-2.8). CONCLUSIONS: This large population-based cohort study indicates that hearing loss is associated with increased risk of receiving disability pension, especially among younger adults and low educated workers. Hearing loss was weakly associated with sick leave.

Concurrent decline in teenage fertility rate and binge drinking? An observational study across 45 nations.

INTRODUCTION: Alcohol consumption is associated with unintended pregnancies among teenagers. Its role as a broader determinant of teenage fertility rates remains unclear. We investigate whether adolescent binge drinking affects the number of teenage births. METHODS: Binge drinking data from 137,898 females aged 15-16 were collected in the HBSC study (2002-2018, 43 countries/regions) and 267,359 in the ESPAD study (1995-2019, 41 countries/regions). Age-specific fertility rates were from the Human Fertility Database and the World Health Organization. We examined changes over time in countries' average levels of binge drinking among female pupils aged 15-16 and population-level fertility rates for the same cohorts when aged 16-19 years. RESULTS: Controlling for differences between countries and survey waves, we found an association between binge drinking and fertility rate, B = 0.019, 95% confidence interval [0.004, 0.034]. When accounting for the countries' time trends, the association was substantially reduced, B = 0.006, 95% confidence interval [-0.0062, 0.0174]. The relationship was not moderated by abortion rates and controlling for contraceptive use had no impact on the findings. DISCUSSION AND CONCLUSIONS: The association between adolescent binge drinking and fertility rates diminishes when accounting for country-specific time trends. Given the lack of clear mechanisms linking binge drinking to trends in fertility rates rather than shorter-term changes, the association likely reflects broader secular trends. Binge drinking may be involved in teen pregnancy and childbirth in individual cases but it does not explain recent developments in teenage fertility rates.

Differences in early life cognitive function explain the association between low education and early dementia risk.

Major initiatives are currently attempting to prevent dementia by targeting modifiable risk factors. Low education is frequently pointed to as a potential key factor, due to its robust relationship with dementia risk. Impact of education is notoriously difficult to assess, however, because of associations with multiple other risk and protective factors, and large population-representative samples are required to tease the relationships apart. Here, we studied 207,814 Norwegian men born between 1950 and 1959 who underwent compulsory cognitive testing during military conscription as young adults, to systematically test associations of education, cognition, and other potentially important factors. While low education was associated with increased risk for dementia diagnosis (Hazard ratio [HR] = 1.37, CI: 1.17-1.60), this association was fully explained by earlier cognitive test scores (HR = 1.08, CI: .91-1.28). In contrast, low cognitive score was associated with double risk of later dementia diagnosis, even when taking education into account (HR = 2.00, CI: 1.65-2.42). This relationship survived controlling for early-life socioeconomic status and was replicated within pairs of brothers. The latter finding suggests that genetic and environmental factors shared within families, such as common genetics, parental education, childhood socioeconomic status, or other shared experiences, cannot account for the association. Rather, independent, non-familial factors are more important. In contrast, within-family factors accounted for the relationship between low education and diagnosis risk. In conclusion, implementing measures to increase cognitive function in childhood and adolescence appears to be a more promising strategy for reducing dementia burden.

Sons and parental cognition in mid-life and older adulthood.

Prior research suggests a relationship between number of sons and maternal long-term health outcomes, including dementia. We assessed the relationship between having sons and parental cognitive aging. Specifically, we investigated the relationship between having at least 1 son and parental baseline cognition level and rate of cognitive decline, accounting for life course sociodemographic characteristics in a cohort of 13 222 adults aged ≥50 years from the US Health and Retirement Study. We included only participants with at least one child. We further explored whether this relationship varies by parental sex and whether the magnitude of the relationship increases with each additional son. Cognition was assessed biennially for a maximum of nine times as a sum of scores from immediate and delayed 10-noun free recall tests, a serial 7s subtraction test, and a backwards counting test. Associations were evaluated using linear mixed-effects models, stepwise adjusting for sociodemographic and health-related factors. In our analytic sample of parents, a total of 82.3% of respondents had at least 1 son and 61.6% of respondents were female. Parents of at least 1 son had a faster rate of cognitive decline in comparison to parents without any son. Our results also suggest that cognitive decline was faster among parents of multiple sons, compared to parents with only daughters. Thus, the results support the theory that having sons might have a long-term negative effect on parental cognition.