A critical analysis of the reported association between vasectomy and frontotemporal dementia.

Dear Editor, Researchers reported an association between vasectomy and primary progressive aphasia (PPA—a rare variety of frontotemporal dementia) in a 2006 manuscript in Cognitive Behavioral Neurology detailing a case–control study that compared 47 men with the disease to 57 controls. The rate of vasectomy in PPA patients was 40% (19/ 47) vs. 16% (9/57) in normal controls. This difference met statistical significance (P50.02). The study also found that there was a younger age of PPA onset for patients who had undergone vasectomy (58.8 vs. 62.9 years; P50.03). Inspired by one patient’s perception of his PPA disease process, these researchers tested a hypothesis of an association between vasectomy and PPA. However, despite proper methodology of case–control design, sound statistical analyses and self-acknowledgement of several of the study’s weaknesses, whether the relationship that they reported on is causal or not remains unclear. A causal link between vasectomy and PPA would have important ramifications for public health and informed consent of vasectomy patients. Our own patients continue to raise concern over this reported association during vasectomy consultation. We thus seek to carefully evaluate the publication reporting this association between vasectomy and PPA, as well as the larger body of medical literature, to determine if the reported association has been further characterized or if causality has been proven.