According to a large new study, men who take testosterone-blocking drugs to treat prostate cancer have nearly twice the risk of developing Alzheimer’s disease compared to men using other treatments. Testosterone-blocking include Lupron, Zoladex, and Eligard. The findings were published on December 7 in the Journal of Clinical Oncology by researchers at Stanford University School of Medicine (Palo Alto, California), and University of Pennsylvania Perelman School of Medicine (Philadelphia, Pennsylvania).
The study authors note that approximately 500,000 men in the United States are taking androgen (male hormone) deprivation therapy for prostate cancer because they want to do undergo some form of treatment for their prostate cancer and may not be candidates for surgery or radiation. They explain that the therapy decreases the levels of testosterone and other male hormones, which can promote the growth of prostate cancer. Furthermore, it has been associated with a higher risk of cardiovascular disease, diabetes, high cholesterol, impotence, loss of muscle mass, depression, breast growth, and hot flashes in men. In addition, several studies have reported that the treatment does not improve survival rates for men with localized prostate cancer.
The goal of the study was to assess the association of androgen deprivation therapy for the treatment of prostate cancer with Alzheimer’s disease risk. The researchers reviewed electronic medical records from Stanford Health Care and Mount Sinai Hospital. They identified 16,888 men with non-metastatic prostate cancer between 1994 and 2013. Among that group, almost 2,400 were treated with anti-androgen therapy. The medical record review revealed that the men treated with testosterone-blocking drugs had an 88% higher risk of being diagnosed with Alzheimer’s disease in the next three years, compared to those who were not. Those men who received the therapy for longer than 12 months had more than twice the risk.
Men treated with testosterone-blocking drugs tend to be older and sicker than those who undergo surgery or radiation; however, the authors noted that they adjusted for such factors. They also wrote that their study was the first to link anti-androgen therapy to Alzheimer’s disease, testosterone has been shown to promote the growth of brain cells and modulate the accumulation of B-amyloid protein, which is the main component of the amyloid plaques seen in Alzheimer’s patients. Low testosterone levels are also associated with higher rates of diabetes, stroke and heart disease, which increase the risk of Alzheimer’s disease.
At present, the use of testosterone-blocking drugs continues to decline for older and sicker men who are not candidates for surgery or radiation. The rate was less than 10% in 2009 for these patients because more men with low-risk tumors have opted for active surveillance instead, according to a 2014 study in European Urology.