Low levels of the male sex hormone, testosterone, in older men is associated with the onset of Alzheimer's disease, according to research by a team that includes a Saint Louis University scientist.
"Having low testosterone may make you more vulnerable to Alzheimer's disease," said John E. Morley, M.D., director of the division of geriatric medicine at Saint Louis University. "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."
Researchers studied 153 Chinese men who were recruited from social centers.
They were at least 55 years and older, lived in the community and didn't have dementia. Of those men, 47 had mild cognitive impairment or problems with clear thinking and memory loss.
Within a year, 10 men who all were part of the cognitively impaired group developed probable Alzheimer's disease. These men also had low testosterone in their body tissues; elevated levels of the ApoE 4 (apolipoprotein E) protein, 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 said.
The findings corroborate findings in previous studies of older Caucasian men that show low testosterone is associated with impaired thinking and Alzheimer's disease. They suggest that testosterone may have a protective value against Alzheimer's disease.
The next step, Morley said, is to conduct a large-scale study that investigates the use of testosterone in preventing Alzheimer's disease. Morley and his co-authors advocate studying the effectiveness of testosterone replacement in older men who have both mild memory problems and low testosterone in staving off Alzheimer's disease.
Panizzon MS, Hauger R, Dale AM, Eaves LJ, Eyler LT, Fischl B, Fennema-Notes
tine C, Franz CE, Grant MD, Jak AJ, Jacobson KC, Lyons MJ, Mendoza SP, Neale MC, Prom-Wormley EC, Seidman LJ, Tsuang MT, Xian H, Kremen WS.
Testosterone modifies the effect of APOE genotype on hippocampal volume in
Neurology. 2010 Sep 7;75(10):874-80.