Taking a particular type of medication to treat an enlarged prostate is associated with a reduced risk of developing Parkinson's disease among men, a new study suggests.

The findings, published in the journal JAMA Neurology, provide compelling evidence that terazosin, and similar medications, might have the potential to prevent or delay the development of Parkinson's disease. "Men taking terazosin were 12 percent to 37 percent less likely to develop Parkinson's disease during follow-up than men taking tamsulosin," said Jacob Simmering, Assistant Professor at the University of Iowa in the US.

The findings build on previous preclinical research by the team, which showed that terazosin enhances cellular energy levels and can prevent or slow the progression of Parkinson's disease in animal models. In this earlier study, the team also used the Truven database to show that men with Parkinson's disease who were also taking terazosin and related drugs had reduced signs, symptoms, and complications of Parkinson's disease. Tamsulosin is another drug commonly used to treat an enlarged prostate, but unlike terazosin, tamsulosin has no effect on cellular energy production, which the team's lab studies suggest is important in terazosin's protective effect.

The new study extends these findings to investigate whether terazosin and related drugs that can also enhance cellular energy production, are associated with a reduced risk of developing Parkinson's disease. For the study, the team identified 150,000 men newly started on terazosin or similar medications and matched them, based on age and clinical history to 150,000 men newly started on tamsulosin. Additionally, the study found that longer duration of use of the energy-enhancing prostate drugs was associated with increased protective effects.