NEW YORK (Reuters Health) - Testosterone supplementation improves spatial memory and constructional abilities in older men with Alzheimer's disease (AD) and mild cognitive impairment, according to investigators.

In a study published in the June issue of Neurology, a group of researchers led by Dr. Monique M. Cherrier, of the University of Washington, in Seattle, examined the efficacy of testosterone supplementation on cognition in men aged 63 to 85 years with AD or mild cognitive impairment. A total of 15 AD patients and 17 mild cognitive impairment patients were enrolled in the double-blind trial.

Nineteen subjects were randomly assigned to receive weekly intramuscular injections of 100 mg testosterone and 13 were assigned to receive weekly injections of placebo for 6 weeks. A battery of neuropsychological tests was conducted at baseline, week 3 and week 6 of treatment, and after 6 weeks of washout.

Subjects in the active treatment group exhibited significantly increased peak testosterone levels (an average of 295%). Patients in this group also had improvement in spatial memory as demonstrated by remembering how to navigate a particular route within a room. They also showed improvement in constructional abilities and verbal memory.

No changes were observed in selective and divided attention or language. No significant increases in prostate specific antigen or hematocrit levels were observed and caregivers of AD patients did not report any change in behavior.

The researchers call for more extensive studies, but conclude that the approach "resulted in some beneficial effects on spatial memory and construction abilities in older men with memory deficits."