Prostate cancer patients receiving androgen deprivation therapy (ADT) are not at increased risk of dementia or Alzheimer’s disease, according to a study in the Journal of Clinical Oncology.

ADT involves depriving patients of androgen hormones such as testosterone, which are necessary for prostate cancer cells to grow. It is the preferred treatment for patients with advanced disease.

Concerns have been raised about whether ADT increases patients’ risk of developing cognitive anomalies and Alzheimer’s disease.

“Cognitive impairment is a known side effect of declining testosterone, in general, so it is naturally of concern with ADT,” said Laurent Azoulay, PhD, lead researcher of the study, “Androgen Deprivation Therapy And The Risk Of Dementia In Patients With Prostate Cancer.” “However, there is a significant difference between cognitive limitations and the biological mechanisms associated with dementia.”

There were “troubling methodological deficiencies” in one study that found a link between ADT and increased risk of dementia and Alzheimer’s, according to a news release.

“Our group was alarmed to see the earlier study that proposed that ADT doubled the risk of Alzheimer disease,” Azoulay said. “Such a dramatic finding called for further investigation and we found some important methodological problems in the study. Because ADT is so often given to older men, very careful statistical analysis is required to assert a causal relationship. Once we applied the correct methodology we found no statistically significant association. However, we would encourage additional studies to confirm our findings.”

Using data from the United Kingdom’s Clinical Practice Research Datalink (CPRD), researchers analyzed the medical records of 30,903 patients diagnosed with nonmetastatic prostate cancer over 27 years.

During a mean follow-up of 4.3 years, 799 patients were diagnosed with dementia. Researchers did not find a link between ADT and the condition.

Secondary analyses — assessing whether the risk varied with the type of ADT or length of use — also failed to show a connection.

“For most every medication there is a judgment to be made between its intended purpose and possible adverse effects,” said Farzin Khosrow-Khavar, the study’s first author and a McGill University doctoral candidate. “There are coping mechanisms to compensate for anticipated issues with cognition. But, if patients believed that ADT doubled their risk of Alzheimer disease they may be reluctant to take it for their cancer. Thus, our analysis should be welcome news for men whose prostate cancer is being controlled with ADT.”