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Key Points Question What are the associations between specific adolescent cognitive abilities and Alzheimer disease and related disorders in later life? Findings In this cohort study of 43 014 men and 42 749 women, lower adolescent memory for words, in women, and lower mechanical reasoning, in men, were associated with higher odds of Alzheimer disease and related disorders in later life. Meaning Low performance on certain specific measures of cognitive ability may indicate future risk of Alzheimer disease and related disorders as early as adolescence.

IMPORTANCE Personality phenotype has been associated with subsequent dementia in studies of older adults. However, neuropathologic changes often precede cognitive symptoms by many years and may affect personality itself. Therefore, it is unclear whether supposed dementia-prone personality profiles (high neuroticism and low conscientiousness) are true risk factors or merely reflections of preexisting disease.OBJECTIVES To examine whether personality during adolescence-a time when preclinical dementia pathology is unlikely to be present-confers risk of dementia in later life and to test whether associations could be accounted for by health factors in adolescence or differed across socioeconomic status (SES). DESIGN, SETTING, AND PARTICIPANTSCohort study in the United States. Participants were members of Project Talent, a national sample of high school students in 1960. Individuals were identified who received a dementia-associated International Classification of Diseases, Ninth Revision (ICD-9) diagnosis code during any year between 2011 and 2013. The dates of our analysis were March 2018 to May 2019. EXPOSURES Ten personality traits were measured by the 150-item Project Talent Personality Inventory. Socioeconomic status was measured by a composite based on parental educational level, income, occupation, and property ownership. Participants were also surveyed on demographic factors and height and weight.MAIN OUTCOMES AND MEASURES Medicare records were collected, with dementia diagnoses in the period of 2011 to 2013 classified according to the US Centers for Medicare & Medicaid Services ICD-9-based algorithm. Cox proportional hazards regression models estimated the relative risk of dementia based on the 10 personality traits, testing interactions with SES and adjusting for demographic confounders. RESULTSThe sample of 82 232 participants was 50.1% female, with a mean (SD) age of 15.8 (1.7) years at baseline and 69.5 (1.2) years at follow-up. Lower risk of dementia was associated with higher levels of vigor (hazard ratio for 1 SD, 0.93; 95% CI, 0.90-0.97; P < .001). Calm and maturity showed protective associations with later dementia that increased with SES. At 1 SD of SES, calm showed a hazard ratio of 0.89 (95% CI, 0.84-0.95; P < .001 for the interaction) and maturity showed a hazard ratio of 0.90 (95% CI, 0.85-0.96; P = .001 for the interaction). CONCLUSIONS AND RELEVANCEThis study's findings suggest that the adolescent personality traits associated with later-life dementia are similar to those observed in studies of older persons. Moreover, the reduction in dementia risk associated with a calm and mature adolescent phenotype may be greater at higher levels of SES. Personality phenotype may be a true independent risk factor for dementia by age 70 years, preceding it by almost 5 decades and interacting with adolescent socioeconomic conditions.

BackgroundIs retirement good or bad for health? Disentangling causality is difficult. Much of the previous quasi-experimental research on the effect of health on retirement used self-reported health and relied upon discontinuities in public retirement incentives across Europe. The current study investigated the effect of retirement on health by exploiting discontinuities in private retirement incentives to test the effect of retirement on health using a quasi-experimental study design.MethodsSecondary data (1997–2009) on a cohort of male manufacturing workers in a United States setting. Health status was determined using claims data from private insurance and Medicare. Analyses used employer-based administrative and claims data and claim data from Medicare.ResultsWidely used selection on observables models overstate the negative impact of retirement due to the endogeneity of the decision to retire. In addition, health status as measured by administrative claims data provide some advantages over the more commonly used survey items. Using an instrument and administrative health records, we find null to positive effects from retirement on all fronts, with a possible exception of increased risk for diabetes.ConclusionsThis study provides evidence that retirement is not detrimental and may be beneficial to health for a sample of manufacturing workers. In addition, it supports previous research indicating that quasi-experimental methodologies are necessary to evaluate the relationship between retirement and health, as any selection on observable model will overstate the negative relationship of retirement on health. Further, it provides a model for how such research could be implemented in countries like the United States that do not have a strong public pension program. Finally, it demonstrates that such research need-not rely upon survey data, which has certain shortcomings and is not always available for homogenous samples.