Adolescent Cognitive Aptitudes and Later-in-Life Alzheimer Disease and Related Disorders.

Importance: Low early-life cognitive ability is a potential early marker of dementia risk in later life. Previous studies use only global measures of general intelligence and/or study this relationship in gender-specific samples. The contribution of early-life performance on specific cognitive abilities, such as language, reasoning, and visualization aptitudes, to indicating future dementia risk is unknown. Objectives: To investigate the association between adolescent cognitive ability and Medicare-recorded Alzheimer disease and related disorders (ADRD) using both general and specific measures of cognitive ability and to explore these associations separately in men and women. Design, Setting, and Participants: Population-based cohort study from the Project Talent-Medicare linked data set, a linkage of adolescent sociobehavioral data collected from high school students in 1960 to participants' 2012 to 2013 Medicare Claims and expenditures data. The association between adolescent cognitive ability and risk of ADRD in later life was assessed in a diverse sample of 43 014 men and 42 749 women aged 66 to 73 years using a series of logistic regressions stratified by sex, accounting for demographic characteristics, adolescent socioeconomic status, and regional effects. Data analysis was conducted from November 2017 to March 2018. Main Outcomes and Measures: Presence of Medicare-reported ADRD. Results: Overall, 1239 men (2.9%) and 1416 women (3.3%) developed ADRD. Lower mechanical reasoning was associated with increased odds of ADRD in men (odds ratio, 1.17; 95% CI, 1.05-1.29), and lower memory for words in adolescence was associated with increased odds of ADRD in women (odds ratio, 1.16; 95% CI, 1.05-1.28). Lower performance on several other language, reasoning, visualization, and mathematic aptitudes in adolescence showed prominent, but weaker, associations with odds of ADRD. Conclusions and Relevance: This work contributes to the understanding of early-life origins of ADRD risk. The results suggest specific measures of cognitive ability may contribute to very early identification of at-risk subgroups who may benefit from prevention or intervention efforts.