Erectile dysfunction drugs may be tied to lower risk of Alzheimer's

"We undertook this study as there was conflicting evidence on the potential association" between erectile dysfunction drugs and Alzheimer's disease, said Ruth Brauer, a lecturer in pharmacoepidemiology and medication safety at the University College London School of Pharmacy in the United Kingdom. Photo courtesy of Ruth Brauer

NEW YORK, Feb. 7 (UPI) -- Medications that treat erectile dysfunction may be tied to a lower risk of Alzheimer's disease, a new study indicates.

The study was published Wednesday in the online issue of Neurology, the medical journal of the American Academy of Neurology. It does not prove that erectile dysfunction drugs decrease the risk of Alzheimer's -- it merely shows an association.

Initially developed to manage high blood pressure and chest pain associated with heart disease, these drugs dilate blood vessels, enabling more blood to flow through.

"We undertook this study as there was conflicting evidence on the potential association" between erectile dysfunction drugs and Alzheimer's disease, Ruth Brauer, the study's corresponding author, told UPI via email.

Brauer is a lecturer in pharmacoepidemiology and medication safety at the University College London School of Pharmacy in the United Kingdom.

A total of 269,725 men, with an average age of 59 and a new diagnosis of erectile dysfunction, participated in the study. At the outset, the men did not have any cognition problems. They were followed for an average of five years.

Researchers compared the 55% of the participants who had prescriptions for erectile dysfunction drugs to the 45% who did not have prescriptions for them.

Over the course of the study, 1,119 people developed Alzheimer's disease.

Among those with prescriptions, 749 developed Alzheimer's disease -- a rate of 8.1 cases per 10,000 person-years. Among those who did not have prescriptions, 370 developed Alzheimer's disease -- a rate of 9.7 cases per 10,000 person-years.

Person-years account for both the number of people in the study and the length of time each person participates in the study.

Researchers adjusted for other variables that could impact the rate of Alzheimer's disease, such as age, underlying health conditions, co-prescribed medications and smoking status.

Their data revealed that people who took erectile dysfunction drugs were 18% less likely to develop Alzheimer's than people who did not take the drugs. The association was most pronounced in those with the most prescriptions over the study period.

"Several extra analyses, for instance by age, were performed in a smaller subset of patients," Brauer said. "These findings cautiously allude to greater benefit" of using these drugs in individuals at greatest risk of Alzheimer's disease -- for example, men 70 years and older.

"Our results warrant further study to investigate this hypothesis."

The study was based on prescription records. However, a limitation stemmed from a lack of information on whether participants actually filled the prescriptions and used the ED drugs.

Another limitation of the study, Brauer acknowledged, is that researchers were unable to account for levels of physical and sexual activity, which may be beneficial in maintaining a level of good cognition and reducing the risk of Alzheimer's disease.

Before erectile dysfunction drugs can be considered for prescribing in Alzheimer's disease prevention, a well-designed randomized controlled trial would be necessary, Dr. Sevil Yaşar, an associate professor of medicine in the Division of Geriatric Medicine and Gerontology at The Johns Hopkins School of Medicine in Baltimore, wrote in an editorial published in the same issue as the study.

"A promising area of research," she wrote, aims to identify drugs approved for other clinical conditions that may be repurposed to prevent the development and progression of Alzheimer's disease.

"To develop a new drug for Alzheimer's disease takes a long, long time," Yasar, who takes care of patients in Johns Hopkins Memory and Alzheimer's Disease Treatment Center, told UPI in a telephone interview.

"There's a lot of interest in drug repurposing. Evaluating the drug group used for erectile dysfunction and also for pulmonary hypertension is a relatively new direction," Yasar said.

That erectile dysfunction drugs may be associated with a reduced risk of Alzheimer's disease shows promise. But she noted that this study was conducted only in men, so the results would need to be confirmed in women.

"We are always looking for mechanisms that contribute to dementia, and blood flow is relevant," said Dr. Ronald Petersen, director of the Mayo Clinic Alzheimer's Research Disease Center and the Mayo Clinic Study of Aging in Rochester, Minn.

"Blood flow to the brain is important for all cognitive functions."

Dilation of blood vessels with drugs that treat erectile dysfunction also lowers blood pressure, which is known to reduce risk for dementia, as well as stroke and heart disease, said Dr. Jack Tsao, a professor of neurology at NYU Langone Health in New York City.

"I think this study will open up new avenues of clinical investigation," Tsao said, calling the outcome "a somewhat unexpected but nonetheless exciting finding."

Although the study demonstrated a strong association between using erectile dysfunction drugs and reduction in Alzheimer's disease risk, the results should not be overstated in sharing this information with the public, Dr. Chris Deibert, a urologist at Nebraska Medicine in Omaha, told UPI via email.

The study's main weakness is that it evaluated people who had already been diagnosed with erectile dysfunction, said Huntington Potter, a professor of neurology and director of the Alzheimer's and Cognition Center at the University of Colorado Anschutz Medical Center in Aurora, Colo.

"Erectile dysfunction is a very strong risk factor for developing Alzheimer's disease, Potter said, noting that study participants already were at high risk. "In ordinary people who are worried about developing Alzheimer's, the study does not show that they would benefit from an erectile dysfunction drug."

Even so, Dr. Michael Eisenberg, a professor of urology at Stanford Medicine in Palo Alto, Calif., said that "Alzheimer's is a devastating disease, and identifying novel therapeutics to delay or avoid onset would be important."