ST. LOUIS — 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 and a study co-investigator. “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.”
The study was published electronically in the Journal of Alzheimer’s Disease and led by Leung-Wing Chu, M.D., who is chief of the division of geriatric medicine at Queen Mary Hospital at the University of Hong Kong.
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.
Established in 1836, Saint Louis University School of Medicine has the distinction of awarding the first medical degree west of the Mississippi River. The school educates physicians and biomedical scientists, conducts medical research, and provides health care on a local, national and international level. Research at the school seeks new cures and treatments in five key areas: cancer, infectious disease, liver disease, aging and brain disease and heart/lung disease.
The idea that hormoonal “instability” play an important role in the development of Alzheimer’s disease and vascular dementia has not been substantially developed. For instance, the relationship between lowered thyroid function and Alzheimer’s disease is not well documented. Osch et al. reported lower levels of TSH among 178 patients diagnosed with Alzheimer’s disease. In the adjusted analysis, the risk of Alzheimer’s disease was more than 2-fold higher compared to controls. In the longitudinal study of 93 patients diagnosed with mild cognitive impairment, a transitional disorder between normal brain function and Alzheimer’s disease, lower thyroid function was found to be a significant predictor of Alzheimer’s disease
Using very large population based data from the National Inpatient Project, I determined that the proportion of patients diagnosed with both hypothyroidism and Alzheimer’s disease was more than twice as high as the proportion of patients diagnosed with Alzheimer’s disease and any other co-morbidity (p < 0.001).
Rovshan M Ismailov, MD MPH PhD
“New Insights into the Mechanism of Alzheimer’s Disease: A Multidisciplinary Approach” Amazon Kindle Book
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