Blocking testosterone can help fight prostate cancer but may put men at higher risk for Alzheimer’s disease.
There are many different treatments for prostate cancer, including surgery, radiation and drug treatment. Some men with low-risk cancers do well with attentive monitoring. Others require more aggressive treatment.
Half a million men with prostate cancer are treated every year with drugs that block testosterone and similar hormones. This approach is called androgen deprivation therapy or ADT. Some men complain that treatment with ADT saps their concentration, undermines their memory and makes it more difficult to multitask. These complaints are reminiscent of those that other cancer patients sometimes make about the experience of “chemo-brain.”
Blocking Testosterone Is Linked to a Higher Risk of Alzheimer’s Disease:
Now a new study confirms an association between blocking testosterone and the subsequent risk of Alzheimer’s disease. The scientists reviewed the records of 16,888 men who had prostate cancer. Almost 2,400 of them had been treated with ADT.
The Absolute Risk of Alzheimer’s Disease Is Extremely Low:
After three years of follow-up, only 125 of all these men had been diagnosed with Alzheimer’s disease. That means the absolute risk of Alzheimer’s disease in this short time is very low.
Even so, it is alarming that those who on ADT were 88 percent more likely to have an Alzheimer’s diagnosis. And those treated for at least a year had double the risk.
Androgen Deprivation Therapy:
Androgen deprivation therapy may be prescribed for two years or longer as part of the treatment of aggressive or recurrent prostate cancer. Although testosterone usually recovers once the treatment is stopped, it can take many months for a man’s testosterone level to return to normal.
Men who are currently undergoing ADT treatment should not stop it without an in depth discussion with the doctor. The evidence for the benefit of blocking testosterone and other male hormones in prostate cancer is quite good, and the risk of Alzheimer’s disease is relatively low.
There is no evidence of cause and effect. Nonetheless, this association is disquieting and deserves further research.
Journal of Clinical Oncology, online Dec. 7, 2015
Previous studies have shown that ADT can also reduce the function of the kidneys. Although this side effect is rare, both doctors and patients should keep it in mind as a possible complication.
