The onset of Alzheimer's disease may be linked to low levels of the male sex hormone testosterone in older men, U.S. and Chinese researchers say.
Dr. John Morley of Saint Louis University in Missouri and Dr. Leung-Wing Chu of Queen Mary Hospital at the University of Hong Kong were co-investigators in a study of 153 Chinese men at least age 55 without dementia.
Forty-seven had mild cognitive impairment -- problems with clear thinking and memory loss -- but within a year, 10 men of the group of 47 developed probable Alzheimer's disease.
The study, published online ahead of print in the Journal of Alzheimer's Disease, finds all 10 had low testosterone in their body tissues and
elevated levels of apolipoprotein E, which is correlated with a higher risk of Alzheimer's disease and high blood pressure.
"It's a very exciting study because we've shown that a low level of testosterone is one of the risk factors for Alzheimer's disease," Morley
says in a statement. "The take-home message is we should pay more attention to low testosterone, particularly in people who have memory problems or
other signs of cognitive impairment."