And here's a paper that fails to find an association between ADT and cognitive impairment

It is generally uncommon for researchers to publish negative results, but this paper does just that and the results are a pleasure to see. The authors of this short report provide data on 2,513 men who were part of the Mayo Clinic Study of Aging in Rochester, Minnesota. Ninety-nine of those men were prostate cancer patients treated with ADT. They were found to have a very slightly elevated risk of cognitive impairment compared to 349 prostate cancer patients not on ADT, but the difference was not statistically significant. Other factors, such as the length of time the men were on ADT, similarly did not show an association with cognitive impairment.

This result contrasts with what we’ve reported here over the last few years, where the majority—but not all studies—have suggested that ADT does increase the risk of cognitive impairment. So, what accounts for these divergent results? 

One factor may be the relatively smaller sample size compared to that of other recent studies. Also, the patient population seen at the Mayo Clinic is not representative of the more diverse cross section of prostate cancer patients in North America treated with ADT.  

To the authors’ credit, they recognize that, despite their own results, the potential side effects of ADT may be a concern to their patients and state that “it is important for physicians to discuss the risk and benefits of ADT with [any of their] prostate cancer patients” who are considering starting on ADT.

To read the study abstract, see: https://www.ncbi.nlm.nih.gov/pubmed/31821185

Quinones, A.H.J., Stish, B.J., Hagen, C., Petersen, R.C., & Mielke, M.M. (2019). Prostate Cancer, Use of Androgen Deprivation Therapy, and Cognitive Impairment: A Population-based Study. Alzheimer Disease and Associated Disorders. Advance Online Publication. doi: 10.1097/WAD.0000000000000366.