Staying Fit
Scientists may have discovered a new use for a drug commonly prescribed to treat erectile dysfunction. A study led by experts at the Cleveland Clinic found that taking sildenafil (brand name Viagra) could dramatically reduce a person’s risk of developing Alzheimer’s disease, though more research is needed. Sildenafil, approved by the U.S. Food and Drug Administration (FDA) 23 years ago, is also used to help people with pulmonary hypertension exercise more comfortably.
In the study, published in the journal Nature Aging, researchers analyzed health insurance claims from over 7 million people and found that those who used sildenafil were 69 percent less likely to develop Alzheimer’s disease after six years of follow-up, compared to nonusers. Interestingly, the study found that use of sildenafil reduced the likelihood of Alzheimer’s in people with coronary artery disease, hypertension and type 2 diabetes — all of which are associated with an increased risk of Alzheimer’s — as well as in those without these high-risk medical conditions.

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Discovering new uses for old drugs
Using a complex network of methodologies, the study team screened a database of 1,608 FDA-approved drugs for medications that could be effective preventive agents or treatments for Alzheimer’s, based on their ability to interact with key proteins that play a role in creating the amyloid plaques and tau tangles that are hallmarks of the disease. Sildenafil emerged as a leader. Other medications that were investigated in the study include diltiazem and losartan (both used to treat hypertension) and glimepiride and metformin (both used to treat diabetes). In a head-to-head comparison with users of these drugs, people who took sildenafil were found to have a 55 to 65 percent lower risk of developing Alzheimer’s.
Study coauthor Feixiong Cheng, a researcher in Cleveland Clinic's Genomic Medicine Institute, cautions that the findings highlight an association and do not prove a causal connection. Still, the results are promising and researchers are already planning to conduct a phase II randomized clinical trial to test the effects of the drug in people with early Alzheimer’s.