Montreal, Quebec—Pharmacists can help ease the fears of certain advanced prostate cancer patients by letting them know that a new large-scale population study found no link between androgen deprivation therapy (ADT) and increased risk of Alzheimer’s disease.

The research, published recently in the Journal of Clinical Oncology, came to different conclusions than a study published last fall in terms of increased risk of dementia related to ADT therapy.

“Cognitive impairment is a known side effect of declining testosterone, in general, so it is naturally of concern with ADT,” explained senior investigator Laurent Azoulay, PhD, an associate professor of epidemiology and oncology at McGill University. “However, there is a significant difference between cognitive limitations and the biological mechanisms associated with dementia.”

Results of a study published in JAMA Oncology late last year indicated that the absolute increased risk of developing dementia among a group of men receiving ADT was 4.4% at 5 years. Men who received ADT at least 12 months had the greatest absolute increased risk of dementia, according to further analysis, which also determined that men >70 who received ADT were the least likely to remain free of dementia.

That research used an informatics approach with a text-processing method to analyze electronic medical records data to examine ADT and the subsequent development of dementia, including senile dementia, vascular dementia, frontotemporal dementia and Alzheimer dementia.

A large-scale, population-based study led by researchers from the Lady Davis Institute at the Jewish General Hospital concluded, however, that the use of ADT to treat advanced prostate cancer is not associated with an increased risk of Alzheimer disease.

In response to the earlier study, the McGill University researchers analyzed a cohort of nearly 31,000 men who were newly diagnosed with nonmetastatic prostate cancer over a 27-year period from the United Kingdom’s Clinical Practice Research Datalink, one of the largest databases of its kind.

“Our group was alarmed to see the earlier study that proposed that ADT doubled the risk of Alzheimer disease,” Azoulay explained. “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.”

The study authors suggest that the findings will be welcomed by clinical oncologists and prostate-cancer patients.

“For most every medication there is a judgment to be made between its intended purpose and possible adverse effects,” added first author Farzin Khosrow-Khavar, 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.”

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