It's an intriguing study that provides "food for thought," as its lead author puts it. Researchers found men who'd been prescribed Viagra and similar PDE5 inhibitor drugs were 18% less likely to develop Alzheimer's over a five-year period than those who hadn't been prescribed the drugs. The finding was even stronger—a 44% lower risk—among the group of men who'd received 21 to 50 prescriptions in total, putting them in the "most-prescribed" tier. But don't call your doctor for a prescription just yet:
- The asterisk: As the Guardian notes, it's an observational study that found correlation, not causation. Essentially, it's still unclear whether the pills offer some form of protection against Alzheimer's or whether men who already had a lower risk of the disease (perhaps because they're more physically active, for instance) are more likely to take Viagra.
- The nuts and bolts of the study: Researchers looked at the medical records of roughly a quarter of a million men who had an erectile dysfunction diagnosis but no known memory issues; about half were taking drugs for their ED. The men were followed for five years (for a total of 1,309,205 person-years of follow-up), with any Alzheimer's diagnoses over that time noted. Researchers logged 8.1 cases of Alzheimer's per 10,000 person-years in the group prescribed the drugs, and 9.7 cases in the group not taking them, reports the BBC.
- The next step: Lead author Dr. Ruth Brauer of University College London says a randomized controlled trial including both sexes would be a beneficial next step. (Fortune notes PDE5s aren't currently approved for use by women in the US.) A researcher not associated with the study points out one quirk of doing a blind trial where the doctors and patients don't know who received the drug and who got a placebo: Viagra's effects are pretty apparent.
(A quirky related read: One city's wastewater
holds an unexpected amount of Viagra.)
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