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Phosphodiesterase type 5 inhibitors (PDE5Is), such as Viagra (sildenafil; Pfizer), used to treat erectile dysfunction may also reduce the risk of developing Alzheimer’s in men by 18%, a study has suggested.
The population-based cohort study, published in Neurology on 7 February 2024, examined IQVIA Medical Research Data UK records of 269,725 men aged ≥40 years (with an average age of 59 years), who were diagnosed with erectile dysfunction between January 2000 and March 2017.
Participants did not have any memory or thinking problems at the start of the study and were followed up for at least 1 year, with a median follow-up of 5.1 years.
During the study, 749 participants taking erectile dysfunction drugs developed Alzheimer’s disease from a total of 1,119 cases.
The authors reported that this corresponded to a rate of 8.1 cases per 10,000 person years, compared with those who did not take the drugs at 9.7 cases per 10,000 person years.
After adjusting for factors that could affect the rate of Alzheimer’s disease, such as age, smoking status and alcohol consumption, researchers found that people who took PDE5Is were 18% less likely to develop Alzheimer’s compared to those who did not take the drugs (hazard ratio [HR]: 0.82 (95% confidence interval [CI]).
The study also found that the associated risk of Alzheimer’s disease was lower in those who were issued more than 20 prescriptions over the study period (HR 0.56 [95%] for 21–50 prescriptions and HR 0.65 [95% CI] for >50 prescriptions).
Commenting on the study, Ivan Koychev, senior clinical researcher at Dementias Platform UK, University of Oxford, said: “The risk appears to be dose dependent, i.e. higher risk reduction with more prescriptions.
“It is also more pronounced in people with heart disease risk factors (high blood pressure, diabetes), suggesting that the effect may be due to neuroprotection through vascular mechanisms,” he added.
“The study is limited through the challenge in drawing causal relationships in epidemiological studies. Also, these types of drugs are typically taken as needed, so it is difficult to know how much was actually taken and at what frequency.
“Overall, this is a significant development as repurposing already-existing drugs for the prevention of dementia is a promising strategy to stop dementia from developing in the first place, using drugs with a known safety profile,” added Koychev.
Alzheimer’s disease is the most common form of dementia, accounting for approximately 50–75% of cases in the UK. There is no cure for the disease; however, there are treatments available, such as monoclonal antibodies, to delay its progression.
According to Office for National Statistics data, highlighted by Alzheimer’s Research UK, dementia and Alzeimer’s disease were the leading causes of death in England and Wales in 2022, accounting for 65,967 deaths, up from 61,250 in 2021.
Leah Mursaleen, head of research at Alzheimer’s Research UK, said: “Developing drugs for diseases like Alzheimer’s is a costly process and can take many years.
“Being able to repurpose drugs already licensed for other health conditions could help accelerate progress and open up new avenues to prevent or treat dementia-causing diseases.
“While this is an encouraging finding, it doesn’t yet confirm whether these drugs are directly responsible for reducing Alzheimer’s risk, nor whether they can slow or stop the disease.”
