Researchers from the University of Pennsylvania found that older prostate cancer patients getting hormone treatment, called androgen deprivation therapy (ADT), were more likely to be diagnosed later with Alzheimer’s disease or dementia. The study was published July 3, 2019 in .

The study authors looked at records from about 154,000 prostate cancer patients in the National Cancer Institute’s SEER database. The men, aged 66 years and older, were diagnosed between 1996 and 2003 and were followed for an average of 8 years. More than 62,000 received ADT within 2 years after their diagnosis, and almost 92,000 did not. Results showed that men treated with ADT were more likely to be diagnosed with Alzheimer’s disease or dementia compared to men who did not get ADT. They also found the risk was higher for men who received more doses of ADT.

• Of the men in the study who received ADT, 13% were diagnosed with Alzheimer’s disease compared with 9% who did not receive ADT.
• 22% of men who received ADT were diagnosed with dementia compared with 16% who did not.
• Men who received more than 8 doses of ADT were at significantly higher risk of both Alzheimer’s disease and dementia diagnoses than those who received fewer than 8 doses.

Study strengths and limitations

The link between ADT and dementia has been studied before, but the results have conflicted. The authors say this study is strong because of the large number of patients observed, the long follow-up period, the connection with higher doses of ADT, and the careful controls of medical and socio-economic factors.

However, they acknowledge that more work needs to be done to identify which men may be already at high risk of developing dementia. It can take more than 10 years for someone with dementia to start showing signs. It’s possible that ADT didn’t cause the dementia seen in the study but may have sped up a process that was already taking place.

Weighing pros and cons of ADT

ADT reduces levels of male hormones in the body, called androgens, to stop them from helping prostate cancer cells grow. It can help some men with high-risk localized or advanced prostate cancer live longer.

But ADT can often cause negative side effects that include reduced sexual desire, impotence, hot flashes, osteoporosis, loss of muscle mass, and depression. The study authors say the risk of dementia is one more possible negative side effect that should be considered when weighing the benefits and risks of ADT, especially for men who have a longer life expectancy because it takes time to develop dementia.