Adrenal responsivity in normal aging and mild to moderate Alzheimer's disease

Enhanced levels of cortisol have been found in moderate to severe Alzheimer's disease (AD) and in major depression, while recent studies have suggested decreased levels of serum dehydroepiandrosterone sulfate (DHAS) in patients with dementia. In this study the responsivity of the adrenal cortex to stimulation with a new low dose adrenocorticotropin (ACTH) test was investigated in patients with AD and in normal aging.

Thirteen patients with mild to moderate AD, 12 healthy old controls, and 15 young controls (78.0 +/- 8.4, 76.7 +/- 7.0, and 28.3 +/- 4.1 years old, mean: +/- SD, respectively) received an intravenous bolus injection of 1 microgram ACTH. Serum cortisol and androgen levels were analyzed before and 5, 10, 20, 25, 30, 35, 40, 60, 90, 120, 180, and 240 minutes after injection.

The cortisol responsivity did not differ between the three groups. An enhanced release of androgens was present in patients with AD. AD per se had an independent influence on androstenedione levels after ACTH stimulation after adjustments for age and gender in a general linear regression model.

In contrast to major depression, increased cortisol release to ACTH stimulation does not seem to be a feature of AD. Abnormal androgen levels after ACTH stimulation are characteristic features of mild to moderate Alzheimer's disease.