"Below average" self-assessed school performance and Alzheimer's disease in the Aging, Demographics, and Memory Study.

BACKGROUND: A low level of formal education is becoming accepted as a risk factor for Alzheimer's disease (AD). Although increasing attention has been paid to differences in educational quality, no previous studies addressed participants' own characterizations of their overall performance in school. We examined whether self-assessed school performance is associated with AD beyond the effects of educational level alone.

METHODS: Participants were drawn from the population-representative Aging, Demographics, and Memory Study (ADAMS, 2000-2002). The ADAMS participants were asked about their performance in school. Possible response options included "above average," "average," or "below average." The ADAMS participants also underwent a full neuropsychological battery, and received a research diagnosis of possible or probable AD.

RESULTS: The 725 participants (mean age, 81.8 years; 59% female; 16% African-American) varied in self-assessed educational performance: 29% reported "above average," 64% reported "average," and 7% reported "below average" school performance. Participants with a lower self-assessed school performance had higher proportions of AD: 11% of participants with "above average" self-assessed performance had AD, as opposed to 12% of participants with "average" performance and 26% of participants with "below average" performance (P < 0.001). After controlling for subjects' years in school, a literacy test score (Wide-Range Achievement Test), age, sex, race/ethnicity, apolipoprotein E-epsilon4 status, socioeconomic status, and self-reported comorbidities, respondents with "below average" self-assessed school performance were four times more likely to have AD compared with those of "average" performance (odds ratio, 4.0; 95% confidence interval, 1.2-14). "Above average" and "average" self-assessed school performance did not increase or decrease the odds of having AD (odds ratio, 0.9; 95% confidence interval, 0.5-1.7).

CONCLUSIONS: We suggest an association between "below average" self-assessed school performance and AD beyond the known association with formal education. Efforts to increase cognitive reserve through better school performance, in addition to increasing the number of years of formal education in early life, may be important in reducing vulnerability throughout the life course.