Prostate Cancer Drugs Are Linked to Dementia

Men need testosterone, but prostate cancer does not. While there is new evidence that use of testosterone replacement therapy does not lead to prostate cancer, once prostate cancer has occurred, it appears to be fueled by testosterone. This is particularly bad news if prostate cancer has penetrated the edges of the gland capsule and begun to spread. In such cases, if local treatment like surgery, radiation, or some form of ablation is no longer an option, the standard of care is to prescribe Androgen Deprivation Therapy (ADT). ADT is essentially chemical castration because it uses prescription drugs as anti-testosterone agents. There are two classes of ADT drugs: a) medication that shuts off the production of androgens as a way to lower the amount available to prostate cancer cells, and b) medication that blocks the ability of the cancer cells to use androgens. ADT does not cure prostate cancer, but in most cases, it delivers a setback that can buy time and possible make other treatments more effective.

For decades, patients have known about the most common side effects of ADT. These include loss of libido (sexual desire) and erectile dysfunction, breast tenderness, weight gain, mood swings, hot flashes, thinning bones, and decreased mental sharpness (dementia).

Dementia is very concerning because it is a syndrome, or collection, of brain deficits. The components of dementia are memory disorders, personality changes, and impaired reasoning and logic. The research associating ADT with dementia has been considered somewhat mixed. Now, a new study by Nead et al. (2017) strongly suggests that developing dementia is a definite risk associated with using ADT for prostate cancer.[i]

The study authors conducted a review of published literature on the problem. They analyzed pooled statistics from studies that reported an observable effect and that controlled for factors that might confound or distort the data. They also collected comparison data based on any occurrence of dementia, regardless of cause. Their cautiously-worded conclusion was that the “…currently available combined evidence suggests that ADT in the treatment of prostate cancer may be associated with an increased dementia risk.” The fact that they recommended that doctors discuss potential cognitive impairment with prostate cancer patients prior to putting them on ADT underscores the strength of their findings.

Patients with advanced prostate cancer that are no longer candidates for local treatment have good motivation for beginning ADT, since it can buy years before the need for chemotherapy. However, ADT is also prescribed in the following cases:

  • Rising PSA suggesting recurrence after surgery or radiation
  • As added therapy before, during or after radiation treatment for patients with evidence of aggressive disease (high Gleason score and high PSA)
  • Before certain types of radiation or ablation to shrink large glands for the sake of treatment effectiveness.

There are no published reports on the length of time a patient would be on ADT before signs of dementia might occur. It stands to reason that the longer the duration, the greater the likelihood of mental impairment. Hopefully, doctors who diagnose advanced disease will have detailed conversations with their patients about the long term benefits and costs of ADT. As for patients with signs of recurrence, thorough diagnosis may reveal that any recurrence is still localized to the gland, and therefore the patient can have a potentially curative ablation procedure.

The Sperling Prostate Center offers state-of-the-art multiparametric MRI for the detection and diagnosis of prostate cancer. Before any treatment decision, imaging is highly advisable to identify the location, extent and aggressiveness of suspected advanced disease or recurrence.


[i] Nead KT, Sinha S, Nguyen PL. Androgen deprivation therapy for prostate cancer and dementia risk: a systematic review and meta-analysis. Prostate Cancer Prostatic Dis. 2017 Mar 28. doi: 10.1038/pcan.2017.10. [Epub ahead of print]