Common prostate cancer treatment linked to dementia risk

A new study is adding to the evidence that a common prostate cancer treatment may raise a man’s risk for dementia.

Researchers from the University of Pennsylvania and Stanford found that a type of hormone therapy called androgen deprivation therapy (ADT) may double the risk of developing dementia.

ADT is used to reduce levels of male hormones called androgens in the body and helps shrink prostate cancers. Androgens, including testosterone, stimulate the growth of prostate cancer cells. Most androgens are made by the testicles. 

Testosterone has been shown to be important for the health of neurons, the nerve cells that carry “messages” in the brain. Because previous studies have linked ADT to Alzheimer’s and other problems associated with brain health, the scientists wanted to take a close look at its relationship with dementia, said study author Dr. Kevin Nead, a resident in the department of radiation oncology at the Perelman School of Medicine at the University of Pennsylvania, and a fellow at Penn’s Leonard Davis Institute of Health Economics.

“We thought that these treatments, because they lower testosterone, could negatively impact neurological health globally and we were interested in seeing if ADT is linked with dementia,” Nead told CBS News.

He and colleagues analyzed data from the medical records of 9,272 men who were diagnosed with prostate cancer between 1994 and 2013. None had been diagnosed with dementia ahead of the study. Their aim was to see who developed any type of dementia – senile dementia, vascular dementia, frontotemporal dementia or Alzheimer’s.

They also looked at the risk over time and found that the absolute increased risk of dementia after five years was 7.9 percent among men who’d undergone ADT treatment compared with 3.5 percent in those who hadn’t had the hormone therapy.

“The relative risk, comparing people who didn’t get the treatment to people who did, there was more than a doubling of risk,” Nead said.

The study, published today in JAMA Oncology, also showed that the prostate cancer patients who’d received ADT for a year or longer had a higher risk for cognitive problems, and so did men over the age of 70.

The researchers adjusted for a variety of variables, including ethnicity, diabetes, cardiovascular disease, cancer, what medications the men were taking, and lifestyle habits such as smoking.

Dr. Paul Wright, chair of the department of neurology at Long Island Jewish Medical Center, in New Hyde Park, New York, and North Shore University Hospital, in Manhasset, New York, told CBS News that it’s “a very informative study, very well done and very interesting.”

“The study overall showed that there was an increase of dementia in a short period of time. And they also showed the longer you’re on it, for one year and above, and the older you are, there is more of a likelihood you’re going to have dementia,” he said.

ADT is a very common treatment, he noted, saying more prospective studies are needed to answer additional questions about how it impacts cardiovascular and other aspects of neurological health – factors which are tied to dementia.

“It raises a lot of questions about how we manage these patients. I don’t think it’s so straightforward and cut-and-dried. There’s more to this than just saying this will result in Alzheimer’s disease,” said Wright, noting that hormone therapy does increase survival in patients.

Nead said it’s hard to find accurate numbers on just how many men undergo hormone therapy for prostate cancer, but he said, “Generally, the number is around 500,000 men in any given year get ADT. Around 50 percent of men who have prostate cancer will at some point get ADT.”

Do oncologists now have an obligation to tell their prostate cancer patients the risks of dementia when they recommend hormone therapy? And will the results change treatment recommendations?

“It’s a tough question. I think, big picture, there are multiple studies even before this one that suggest ADT might be associated with cognitive changes. The current study definitely supports that. Based on the body of literature that exists now, it would be beneficial to talk to patients about cognitive risks,” Nead said.

But he said he wouldn’t recommend changing treatment plans until further prospective studies are conducted – studies that could follow patients over a long period of time to track neurocognitive and other health changes.