More education may limit the impact of cognitive impairment on disability and life expectancy for older Americans

Cognitive impairment in older age is a major cause of disability. We examined effects of education on life expectancy and life-course disability associated with cognitive impairment. We followed a cohort ages 55+ in 1992 (mean 67.4) for 17 years using the U.S. Panel Study of Income Dynamics (n=2,165). The outcome measure was disability in activities of daily living, such as bathing, dressing, and eating. Cognitive health was repeatedly measured by asking, “Has a doctor ever told you that you have permanent loss of memory or mental ability?” Focusing on individuals with cognitive impairment, we estimated monthly probabilities of disability transitions and death with multinomial logistic Markov models with seven levels of education, adjusting for age, gender, income and other confounders. Most measures were updated at each wave. Random effects adjusted for multiple observations for individuals. The disability probabilities were used to conduct microsimulations, creating large populations with monthly disability records from age 55 to death for each individual. Bootstrapping addressed survey design. There was a strong gradient associating education with disability. Given survival to age 55, average total years lived and years with disability among women with cognitive impairment were 90.8/9.6 for the highest education group (>16 years), 81.9/13.0 for the lowest (<8 years), with a linear trend between these end-points (p<0.0001). Corresponding results for men were 89.9/7.7, 80.5/10.7. Thus, the proportion of remaining life with disability comparing low to high education was 81.4% greater for women, 91.9% for men. Education may substantially limit disability associated with cognitive impairment.