In a recent study, researchers from Penn Medicine find that a common hormone therapy to treat prostate cancer may double a man’s risk of dementia, regardless of his age.
The Penn Medicine study is published in JAMA Oncology.
Androgens (male hormones) normally play a key role in stimulating prostate cell growth. Therapies that suppress androgen production or activity are often used in treating prostate tumors.
However, researchers find that drastically reducing androgen activity can have adverse side-effects.
Previous studies have found links between low testosterone levels and obesity, diabetes, high blood pressure, and heart disease. All these conditions are known risk factors for dementia.
Recently, researchers discovered a dramatic association between Alzheimer’s disease and androgen deprivation therapy (ADT).
ADT is a mainstay of treatment for prostate cancer since the 1940s currently used in over half million men in the United States.
Research in recent years also has linked ADT and low testosterone to cognitive deficits and has shown that men with Alzheimer’s tend to have lower testosterone levels, compared to men of the same age who don’t have the disease.
However, it is currently unknown if ADT may contribute to the risk of dementia.
In the study, the team compared the medical records of almost 9,500 prostate cancer patients who received ADT vs. those who did not.
The finding of the study showed that the ADT group, compared to the control group, had significantly more cases of dementia in the years following the initiation of ADT.
The absolute increased risk of developing dementia was 4.4% at five years: 7.9% among those who received ADT vs 3.5% in those who did not, which is more than double the risk. The results were statistically significant.
The analyses also suggested a “dose-response effect.” Patients who had been receiving ADT for at least 12 months had the greatest risk of dementia, they found.
There was also no evidence of an interaction between use of ADT and age. The risk was doubled in both age groups.
The probability of developing dementia at five years was 13.7% in men over 70 who had ADT vs. 6.6% in men over 70 who did not.
For men younger than 70, it was 2.3% in those who had the therapy vs. one percent for those who did not.
While the study does not prove that ADT increases the risk of dementia, it does strongly supports that possibility.
There are several plausible mechanisms that may explain the association between ADT and dementia.
There is some evidence that testosterone has a general protective effect on brain cells, so that lowering testosterone would leave the brain less able to resist the processes leading to dementia and Alzheimer’s.
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