ADT stands for "androgen-deprivation therapy" and is the standard type of treatment for prostate cancer that has spread to the bones or other organs.
ADT lowers the level of male hormones, like testosterone, which can feed prostate cancer cell growth. Medications used for hormone therapy for prostate cancer include Lupron and Zoladex.
The data review was carried out by Christian Nelson, PhD from the department of psychiatry and behavioral sciences at Memorial Sloan-Kettering Cancer Center in New York.
The researchers note that few studies have been done to assess the effect of hormone therapy on mental functioning. Most have been small studies with contradictory results.
In looking at nine studies of men with prostate cancer taking ADT, the researchers found that between 47% and 69% of men receiving hormone therapy for prostate cancer had declining brain function in at least one cognitive area. However, there were contradictory findings for some cognitive areas such as verbal memory.
The researchers write that there is a "strong argument" to be made that the hormone therapy is linked to "subtle but significant" cognitive declines in men with advanced prostate cancer. They urge larger and longer studies to investigate the issue further. They also suggest investigating whether known side effects of hormone therapy for prostate cancer play a part in mental decline.
The researchers add that more men with earlier stages of prostate cancer are getting hormone therapy. They urge doctors to be aware of the potential downsides to the therapy so they can let their patients know and make sure they are watched for mental effects.
The review is published online in the Sept. 1 issue of Cancer.