A prospective study of dehydroepiandrosterone sulfate and cognitive function in an older population: the Rancho Bernardo Study.

OBJECTIVE: To determine whether low plasma dehydroepiandrosterone sulfate (DHEAS) levels predict poor cognitive function in the elderly.
DESIGN: A prospective, population-based study with periodic clinical evaluations and 100% follow-up for vital status.
SETTING: Rancho Bernardo, California PATIENTS: 270 men and 167 women (80% of surviving, local, age-eligible subjects) from the Rancho Bernardo cohort who had plasma obtained for DHEAS assays in 1972 to 1974 and screening for dementia in 1988 to 1991. MEASUREMENTS: DHEAS levels were measured by radioimmunoassay. There were five interviewer-administered standard screening tests of cognitive function: Mini-Mental Status Examination, Buschke selective reminding test, Trails B, category fluency, and Heaton Visual Reproduction test.
RESULTS: DHEAS levels were higher in men than women and decreased with age in both sexes. There were no significant differences in age-adjusted DHEAS levels in the percent of men or women with categorically impaired performance on any test. When analyzed as a continuous variable, DHEAS levels were significantly correlated with only one test, the Bushke, and only in women. Low baseline DHEAS levels were not associated with any mention of dementia on death certificates or with non-participation of survivors. Low levels of DHEAS predicted mortality in men more than in women such that men were more likely to have died before cognitive function testing than women.
CONCLUSION: The single DHEAS-memory association, restricted to women, is most likely to be spurious, consequent to multiple comparisons. We cannot exclude a true effect of low DHEAS, restricted to women and reflecting their better survival than men.