By: Dan Sperling, MD

A study published in the prestigious Journal of Clinical Oncology (December, 2015) rattled the prostate cancer treatment world. A common treatment called androgen deprivation therapy (ADT or chemical castration) appears to double the risk of Alzheimer’s disease. The study, out of Stanford University and the University of Pennsylvania, caught the attention of the media. Reports and articles appeared on NBC News and in sources such as WebMD, Medscape, the New York Times and Renal & Urology News.

“Androgen Deprivation Therapy and Future Alzheimer’s Disease Risk,” is the culmination of analyzing 16,888 case records of patients from Stanford and Mt. Sinai Hospitals.[i] After sifting through the records, the research team identified 2,397 men on ADT who met their inclusion and exclusion criteria. The average length of follow-up was 2.7 years. What they found was startling, especially because ADT has been a standard of care for over a half century.

The study found that PCa patients on ADT had a 1.88 greater risk of Alzheimer’s disease than PCa patients who had never been on ADT. For those who used ADT longer than 12 months, the risk increased to 2.12 higher. The research team filtered out other conditions like senile dementia, and other possible causes for Alzheimer’s, since the case records contained specific diagnostic information. Therefore they had a high degree of confidence in the association they found.

ADT is a prostate cancer (PCa) management strategy that controls the growth of PCa by depriving it of testosterone, which fuels its growth. Pharmaceutical agents, both injectable and oral, block a man’s body from producing male hormones, which is why ADT is often referred to as chemical castration. ADT is not curative but it can curtail the cancer for years; eventually, however, the cancer cells mutate to a point at which ADT is no longer effective, and patients then go on chemotherapy. ADT causes side effects that can affect quality of life: hot flashes, mood swings, breast tenderness, loss of sex drive, and bone loss can be troublesome to cope with. For most ADT patients, this is an acceptable trade-off in order to gain more years of life.

The Stanford/U.Penn study is not the first to correlate ADT with diminished cognitive function.  A small study (48 advanced PCa patients) out of the University of South Florida compared their patients with 84 men who had prostatectomies but not ADT and 88 men without PCa[ii]. Those who went on ADT were tested for mental function before they began the drugs, and again at 6 months and 12 months after starting on ADT. Compared with the other two groups, the ADT patients had less mental clarity together with general signs of impaired thinking.

While the Stanford/U.Penn research sounds discouraging, it’s important to not globalize its findings. The authors urge PCa patients who are at risk of advanced or metastatic PCa, and who can be helped by ADT, to discuss the situation thoroughly with their doctors. Our Center wishes to emphasize the importance of early detection, and the value of 3T multiparametric MRI if there is a suspicion of PCa. Knowing the facts about an individual’s disease is the foundation for making the most appropriate treatment choice.

[i] Nead K, Gaskin G, Chester C, Swisher-McClure S, Leeper N and Shah N. Androgen deprivation therapy and future Alzheimer’s disease risk.” JCO 2015(Dec). Published online before printDecember 7, 2015, doi:10.1200/JCO.2015.63.

[ii] http://www.webmd.com/prostate-cancer/news/20150512/hormone-therapy-for-prostate-cancer-may-impair-thinking, May 12, 2015.