Antecedents of intact cognition and dementia at age 90 years: a prospective study

Objectives: This study aimed to examine the possible antecedents of both dementia and sustained intact cognition at age 90 years among men who underwent a prospective, multidisciplinary assessment from ages 19 to 90 years, with little attrition.

Methods: We conducted a prospective 20-year reassessment of 196 (out of 268) former Harvard college sophomores who survived until age 70 years. Since 1939, the study gathered measurements of childhood environment, dominant personality traits, objective mental and physical health over time, smoking in pack-years, alcohol abuse, and depression. Questionnaires were obtained every 2 years and physical exams every 5 years. Cognitive status was assessed at ages 80, 85, and 90 years.

Results: Despite addressing a wide variety of health, behavioral, and social factors over the lifespan, we observed few predictors with strong association with either intact cognition at age 90 years (n = 40) or dementia (n = 44). Univariate analysis revealed seven suggestive predictors of intact cognition at age 90 years or of dementia: warm childhood relationship with mother, exercise at age 60 years, high maternal education, young age of mother at subject's birth, low body mass index, good physical health at 60 years, and late retirement. Only the first three variables, warm childhood relationship with mother, exercise at age 60 years, and high maternal education, remained significant with logistic regression.

Conclusions: In this prospective study of long-lived, highly educated men, several well-known putative predictors of Alzheimer's disease did not distinguish those who over the next 20 years developed dementia from those with unimpaired cognition until age 90 years.