Prostate cancer is hard enough by itself. That’s because treatment often comes with unpleasant complications. Now, add the possibility of Alzheimer’s disease and/or dementia linked to testosterone suppression (androgen deprivation therapy or ADT). The latest research was published in JAMA Network Open (July 3, 2019). It means that men diagnosed with prostate cancer now face a difficult dilemma. Weigh the benefit of lowering testosterone levels, which delays prostate cancer progression, against the risk of developing Alzheimer’s disease. That decision sucks. Nevertheless, urologists and oncologists should now discuss the tradeoffs between prostate cancer therapy and dementia.
The Latest Research Linking Prostate Cancer Therapy and Dementia
Investigators at the University of Pennsylvania Perlman School of Medicine followed nearly 155,000 older men for at least 10 years. These gentlemen were included in a Medicare database. They were at least 66 years of age and had been “diagnosed with localized or advanced prostate cancer between 1996 and 2003.”
Over 62,000 of them received androgen deprivation therapy within two years of diagnosis. This involves the suppression of testosterone with anti-androgen medications. Roughly 92,000 did not receive hormone suppression treatment.
Exposure to androgen deprivation therapy was linked to an increased risk of both Alzheimer disease and dementia in these Medicare patients. Of those who received testosterone suppression, 21.6% were diagnosed with dementia over the decade of follow-up. Men who did not have their hormones blocked had a 15.8% risk of dementia.
What makes this research a little more convincing is the dosing data. The association between prostate cancer therapy and dementia was stronger depending upon the total ADT exposure.
Prostate Cancer Therapy and Dementia | The Number Needed to Harm:
One of the ways physicians judge the benefits and risks of medications is the number needed to treat and the number needed to harm. In plain English, how many people need to take a medicine for one to get measurable benefit? It often takes 20 or 30 individuals taking a drug for five years for one to see a benefit. In the case of statins it is even more than that. Doctors also like to know how many men will be harmed from a particular treatment.
The authors of the recent ADT study report that:
“The number needed to harm was 18 patients for Alzheimer disease and 10 patients for dementia.”
For many men those odds may be worth it. One out of 18 patients would be predicted to develop Alzheimer’s disease over a decade if testosterone were suppressed for several months or a year or two. Roughly one man out of 10 would be likely to develop dementia over a decade.
Other Research Linking Prostate Cancer Therapy and Dementia:
This is not the first study to suggest that depriving the body of testosterone can have an impact on the brain. A study conducted in Taiwan collected data on over 24,000 prostate cancer patients (Aging Male, March, 2017). Over four years the men who received ADT were 84% more likely to develop Alzheimer’s disease (AD) than men who did not have their hormones suppressed. The authors concluded:
“The present results suggest that ADT use is associated with an increased risk of developing AD.”
“The currently available combined evidence suggests that ADT in the treatment of prostate cancer may be associated with an increased dementia risk. The potential for neurocognitive deficits secondary to ADT should be discussed with patients and evaluated prospectively.”
The Flip Side of Prostate Cancer Therapy and Dementia:
“Our analysis of FDA MedWatch adverse event data reports does not support the idea that androgen deprivation therapy per se is associated with Alzheimer’s disease or cognitive dysfunction. Perhaps the prostate cancer itself, or the stress it imposes on the man who has it, may be detrimental to mood and intellect, increasing susceptibility to Alzheimer’s disease and cognitive disorder.”
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What Happens when Testosterone Levels are Lowered?
Testosterone is not an accident. Men and women rely on this hormone for a number of essential physiological processes. Although it is often referred to as a male hormone, women make testosterone too.
When the body is deprived of testosterone there is a greater risk for muscle wasting and weakness. This hormone is also important for good bone health. When testosterone levels are low, there is a greater risk for bone loss and osteoporosis.
Other side effects associated with testosterone deprivation include breast development (gynecomastia), erectile dysfunction (ED), difficulty concentrating, depression, hot flashes and possibly even heart disease (Journal of Clinical Oncology, June, 2007).
The Benefits of ADT
For the record, let’s be very clear. Androgen deprivation therapy improves outcomes in prostate cancer patients. There is evidence that ADT and lower levels of testosterone are associated with “reduced risk of death and progression” (Clinical Genitourinary Cancer, June, 2018).
Balancing The Pros and Cons of ADT:
Prostate cancer is a leading killer of men. It is the second most common cause of cancer death in this population. Treatment is often very confusing. There are no easy answers and no perfect solutions.
ADT is one of the pillars of therapy, whether men receive radiation or some other approach. It is a sad commentary on current prostate cancer treatment that we do not have clear answers about the best approach to stave off this disease.
Men with PCa need to weigh the benefits and the risks of ADT. Physicians need to be honest about the pros and cons of androgen deprivation therapy so men can make informed decisions. Each man will have to decide for himself what the best path forward will be.
If you have had ADT, please share your experience in the comment section.
Joe Graedon is a pharmacologist who has dedicated his career to making drug information understandable to consumers. His best-selling book, The People’s Pharmacy, was published in 1976 and led to a syndicated newspaper column, syndicated public radio show and web site. In 2006, Long Island University awarded him an honorary doctorate as “one of the country's leading drug experts for the consumer.” Read Joe's Full Bio.
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