Apolipoprotein E ε4 and testosterone interact in the risk of Alzheimer's disease in men

Objectives To assess the association between testosterone levels and APOEepsilon4 in cases with AD and controls. Method We included 61 men with definite or probable Alzheimer's disease (AD) and 55 elderly male controls from the Oxford Project to Investigate Memory and Ageing (OPTIMA). Testosterone was measured using a competitive enzyme immunoassay (Bayer(R)). Results We found that both low serum testosterone and the interaction between testosterone and APOEepsilon4 were associated with AD. Furthermore, testosterone levels were lower in APOEepsilon4-positive controls (mean: 11.3 nmol/L) than in controls without the allele (19.1 nmol/L). Conclusions Low testosterone is potentially a modifiable risk factor, which may prove relevant to APOEepsilon4 carriers who are at risk of AD. Copyright (C) 2002 John Wiley Sons, Ltd.