Serum testosterone levels in males with Alzheimer's disease

This study aimed to investigate whether there are differences in serum testosterone levels between male patients with Alzheimer's disease (AD) and cognitively normal male controls. Testosterone and sex hormone binding globulin (SHBG) levels were measured from 14 patients with mild to moderate AD and 16 age-matched control males. The AD patients had higher levels of serum total (P = 0.02) and free testosterone (P < 0.001), and higher free androgen index (FAI) (P = 0.02) compared to controls. No differences were found for the SHBG levels. These data provide no support for hypotheses of (disproportionally) decreased levels of serum testosterone in AD. These data also show that all cognitively normal controls had an FAI below the normal range.