In a recent study from Penn Medicine, researchers find that a common hormone therapy to treat prostate cancer may double a man’s risk of dementia, regardless of his age.
Androgens (male hormones) normally play a key role in stimulating prostate cell growth.
Thus, therapies that suppress androgen production or activity are often used in treating prostate tumors.
Androgen deprivation therapy (ADT) is a mainstay of treatment for prostate cancer since the 1940s.
It is currently used in over half million men in the United States.
But drastically reducing androgen activity can have adverse side-effects.
For example, studies have found links between low testosterone levels and chronic health conditions like obesity, diabetes, high blood pressure, and heart disease.
All these conditions are also known risk factors for dementia.
Research in recent years also has linked ADT and low testosterone to cognitive deficits.
It also 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.
In the current study, the researchers analyzed the medical records of almost 9,500 prostate cancer patients who received ADT vs. those who did not strongly supports that possibility.
The team used a novel and sophisticated “text-processing” method to analyze electronic medical records from patients treated at an academic medical center from 1994 to 2013, with a median follow-up of 3.4 years.
The team identified 9,277 men with prostate cancer with a mean age of 66.9 years, including 1,826 men who received ADT.
They found that the ADT group, compared to the control group, had much 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 researchers also found a “dose-response effect”: Patients who had been receiving ADT for at least 12 months had the greatest risk of dementia.
There was no evidence of an interaction between 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. 1% for those who did not.
The researchers suggest that there are more than one plausible mechanisms that may explain the association between ADT and dementia.
For instance, 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.
The researchers warn that the findings do not prove that ADT increases the risk of dementia, but the study suggests a broader neurocognitive risk associated with the testosterone-lowering therapy.
The study is published in JAMA Oncology.
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