In conclusion, this small prospective study in healthy older subjects indicates that there may be an association between adrenal steroid hormones and cognitive function. Free cortisol appeared to be associated with cognitive impairment, and cortisol after dexamethasone treatment increased the risk of cognitive decline. DHEAS was inversely, but not significantly, associated with cognitive impairment and decline. However, these results are preliminary, and larger follow-up studies of longer duration are needed to verify these findings. It remains unclear whether the observed cognitive impairment and decline are the direct result of the altered levels of the peripheral steroids or vice versa, or if another factor influences both adrenal steroid biosynthesis and the processes leading to reduced cognitive function.Received September 30, 1997. Revised June 12, 1998. Accepted June 19, 1998.