Common Prostate Cancer Therapy Linked to Increased Risk of Dementia

Risk nearly doubles after long-term use of ADT

Men with prostate cancer being treated with a common hormone therapy may be doubling their risk of dementia, a recent study says.

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The study, conducted by researchers at the University of Pennsylvania, showed an association between the use of androgen deprivation therapy (ADT) and increased risk of dementia.

The researchers studied electronic medical records of more than 9,000 men diagnosed with prostate cancer and looked to see who was diagnosed with dementia during follow-up. Men who had been on ADT for at least a year had a higher likelihood of developing dementia, as did men who started ADT after age 70.

ADT also has been associated with metabolic syndrome, which raises the risk of heart disease, diabetes and stroke.

Androgens and prostate cancer

Prostate cancer develops when mutant cells in your prostate grow out of control. Experts don’t know what starts it. But they do know that the male sex hormones called androgens — which include testosterone — fuel it.

That’s why doctors often fight prostate cancer — especially when it’s advanced — with ADT in addition to radiation therapy, prostate removal or other treatments.

Men undergoing ADT may take medicines that stop their body from making or reacting to androgens. Sometimes ADT involves surgically removing the testicles, where most androgen is made.

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ADT is the first-line treatment for prostate cancer that has spread, in order to stop its growth. With ADT, prostate cancer cells don’t grow as fast, if at all.

Unfortunately, ADT doesn’t usually work long-term. Prostate cancer cells eventually find a way to make their own androgen.

The connection between androgen and brain function

The study is the first to show such a significant association between dementia and ADT , says urologist Eric Klein, MD. Dr. Klein did not take part in the study.

The study’s authors say their research extends previous work that supports an association between use of ADT and Alzheimer’s disease and suggests that ADT may more broadly affect neurocognitive function.

“There’s always been this question about whether testosterone is really required for good brain function in older men,” Dr. Klein says. “The study went a step further and looked at whether men who had been on androgen deprivation therapy for some time have a higher incidence of dementia. That’s exactly what, in fact, it showed. The incidence was nearly double.”

Dr. Klein cautions, however, that while intriguing, the study did not demonstrate cause and effect between ADT and dementia. Researchers used a text-processing method to analyze electronic medical record data of men who had prostate cancer and later went on to develop dementia.

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Talk with your doctor

If you have prostate cancer, it’s important to talk over the risks and benefits of ADT with your oncologist, Dr. Klein says.

“Androgen deprivation therapy works very well for slowing down the growth of prostate cancer, but it should only be used in appropriate circumstances,” he says.

 Dr. Klein says more research is needed to better understand the association between ADT and brain function.

Complete results for the study appear online in the journal JAMA Oncology.