A large-scale, population based study has found no link between the use of androgen deprivation therapy (ADT) to treat advanced prostate cancer and the development of Alzheimer disease. The findings, published in the Journal of Clinical Oncology, are important as they calm fears raised by a previous controversial study that found a troubling connection between ADT and Alzheimer’s disease.
ADT is a form of chemical castration that is prescribed to eliminate testosterone in men with advanced prostate cancer, a disease fuelled by testosterone. It is widely used and so effective at stopping the progress of cancer that men are often treated with ADT for many years.
“Cognitive impairment is a known side effect of declining testosterone, in general, so it is naturally of concern with ADT,” said Dr. Laurent Azoulay, Senior Investigator with the Lady Davis Institute at the Jewish General Hospital and 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.”
Azoulay and Farzin Khosrow-Khavar, a McGill University doctoral candidate, discovered some methodological problems in the studies that found the ADT-Alzheimer’s link.
“Our group was alarmed to see the earlier study that proposed that ADT doubled the risk of Alzheimer disease. Such a dramatic finding called for further investigation and we found some important methodological problems in the study,” said Azoulay.
Thus, they conducted a new study of nearly 31,000 men who had been newly diagnosed with nonmetastatic prostate cancer over a twenty-seven year period from the United Kingdom’s Clinical Practice Research Datalink.
“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,” said Azoulay.
The American Society of Clinical Oncology (ASCO) was quick to highlight Azoulay’s study because of its immediate clinical importance. It wanted to make sure that clinicians who may have become reluctant to prescribe ADT in light of the initial controversial findings were reassured that a causal link was not found in later research.
“For most every medication there is a judgment to be made between its intended purpose and possible adverse effects,” said first author Khosrow-Khavar. “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.”
Source: McGill University