A PROSPECTIVE-STUDY ON CORTISOL, DEHYDROEPIANDROSTERONE-SULFATE, AND COGNITIVE FUNCTION IN THE ELDERLY

The objective of this study was to investigate the relation between th e peripheral concentrations of the adrenal steroid hormones cortisol a nd dehydroepiandrosterone sulfate (DHEAS) and cognitive impairment and decline. A prospective study design was used. The setting was a subur b of Rotterdam, The Netherlands. The study population consisted of a s ample of 189 healthy participants from the population-based Rotterdam Study, aged 55-80 yr, who were invited for an additional examination. Follow-up examinations took place 1.9 yr after baseline, on the averag e. We determined fasting blood levels of DHEAS before dexamethasone ad ministration and of cortisol and corticosteroid-binding globulin befor e and after the administration of 1 mg dexamethasone overnight. The 30 -point Mini-Mental State Examination (MMSE) was used to assess cogniti on. The associations with cognitive impairment (MMSE score of <26; 6% of the sample) and cognitive decline (drop in MMSE score of >1 point/y r; 24%) were estimated using logistic regression, with adjustment for age, sex, education, and depressive symptoms. An increase of 1 sn in t he estimate of free cortisol (sn = 30.3) was associated with cognitive impairment, although not significantly [odds ratio (OR) = 1.5; 95% co nfidence interval (CI), 0.9-2.4]. A 1 so increase in the natural logar ithm of cortisol after the administration of 1 mg dexamethasone (sn = 0.68) was associated with an OR for cognitive decline of 1.5 (95% CI, 1.0-2.3). A 1 SE increase in DHEAS (SD = 2.10 mu mol/L) was inversely, but nonsignificantly, related to cognitive impairment (OR = 0.5; 95% CI, 0.2-1.1) and cognitive decline (OR = 0.6; 95% CI, 0.4-1.1). The ra tio of free cortisol over DHEAS was significantly related to cognitive impairment (OR = 1.8; 95% CI, 1.0-3.2). This prospective study among healthy elderly subjects suggested that basal free cortisol levels wer e positively related to cognitive impairment, and cortisol levels afte r dexamethasone treatment were related to cognitive decline. There was an inverse, but nonsignificant, association between DHEAS and cogniti ve impairment and decline.