London, Feb 8(IANS): The drugs used to treat erectile dysfunction may also be associated with a reduced risk of Alzheimer's disease, according to a study.

The study, published in the journal Neurology, does not prove that erectile dysfunction drugs reduce the risk of Alzheimer's disease. It only shows an association.

Erectile dysfunction drugs, which work by dilating blood vessels to allow more blood to flow through, were first developed to treat high blood pressure.

"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," said Ruth Brauer, from the University College London in the UK.

"These results are encouraging and warrant further research."

The study involved 269,725 male participants with an average age of 59 who were newly diagnosed with erectile dysfunction.

Participants did not have any memory or thinking problems at the start of the study. They were then followed for an average of five years. The study compared the 55 per cent of the participants who had prescriptions for erectile dysfunction drugs to the 45 per cent who did not have prescriptions.

During the study, 1,119 people developed Alzheimer’s disease.

Among the participants taking erectile dysfunction drugs, 749 developed Alzheimer’s disease, which corresponds to a rate of 8.1 cases per 10,000 person-years.

Person-years represent both the number of people in the study and the amount of time each person spends in the study. Among those who did not take the drugs, 370 developed Alzheimer's disease, which corresponds to a rate of 9.7 cases per 10,000 person-years.

Once researchers adjusted for other factors that could affect the rate of Alzheimer's disease, such as age, smoking status and alcohol consumption, they found that people who took erectile dysfunction drugs were 18 per cent less likely to develop Alzheimer’s than people who did not take the drugs.

The association was strongest in those who were issued the most prescriptions over the study period.

"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," Brauer said.

"A randomised, controlled trial with both male and female participants is warranted to determine whether these findings would apply to women as well," Brauer said.