Men prescribed erectile dysfunction drugs such as Viagra and Cialis were 18 per cent less likely to develop Alzheimer’s disease, a new study has found.
The finding provides some hope that these drugs could be repurposed to prevent a common form of dementia, but more clinical trials are needed to determine whether there is a causal link.
The new UK study included nearly 270,000 men who were diagnosed with erectile dysfunction and had no cognitive problems at the beginning of the study.
Around 55 per cent of the men were taking drugs such as sildenafil (Viagra), tadalafil (Cialis), vardenafil, and avanafil, which are known as phosphodiesterase type 5 inhibitor drugs that act by dilating blood vessels.
Published in the journal Neurology, the research found that the link between the drugs and reduced risk of Alzheimer’s was stronger among those who had the most frequently issued prescriptions.
"Although we’re making progress with the new treatments for Alzheimer’s disease that work to clear amyloid plaques in the brain for people with early stages of the disease, we desperately need treatments that can prevent or delay the development of Alzheimer’s disease," Dr Ruth Brauer, lead author from the University College London School of Pharmacy, said in a statement.
"More research is needed to confirm these findings, learn more about the potential benefits and mechanisms of these drugs, and look into the optimal dosage," she added.
Need for controlled trial with both sexes
The researchers suggest that a randomised, controlled trial with both sexes could help to confirm whether there is a direct link between the drugs and reduced risk for Alzheimer’s.
Alzheimer’s disease is the most common form of dementia and impacts around 7.8 million people in the European Union. Its hallmark symptoms include a decline in memory function and thinking skills.
Erectile dysfunction drugs such as Viagra were initially developed to treat hypertension and angina. Some studies in animals have shown "possible neuroprotective benefits" from the drugs, the researchers said.
Among men in the study who were prescribed erectile dysfunction drugs, there were 8.1 cases per 10,000 person-years, which represents the number of study participants and the amount of time they were observed in the study.
In comparison, among men not taking the drugs, there were 9.7 cases per 10,000 person-years.
The mean age of participants at the beginning of the study was 58.5 and there was a median follow-up of 5.1 years.
Contentious link
Dr Ivan Koychev, senior clinical researcher at the University of Oxford and clinical scientist at Dementias Platform UK, said in a statement that the study was limited due to "the challenge in drawing causal relationships in epidemiological studies".
Koychev, who was not associated with the study, added that these types of erectile dysfunction drugs are typically taken as necessary, so it’s hard to determine how much and how often men take them.
"The link to Alzheimer’s disease in particular is contentious as it is known that a significant proportion of dementia cases diagnosed as Alzheimer’s clinically have additional or alternative pathologies," he added.
But as repurposing already existing drugs to prevent dementia is a "promising strategy," he said, clinical trials could show how useful the drugs are in reducing the risk of Alzheimer’s disease.
