One of the world's most famous drug classes may be up to another trick. In a new study, British scientists find that erectile dysfunction drugs like sildenafil (commonly known as Viagra) are associated with a lower risk of Alzheimer's disease, the most common form of dementia. I discovered that. The research team said the findings do not prove causation, but there is value in clinical trials that can confirm true benefits.
Sildenafil and similar drugs are called phosphodiesterase type 5 inhibitors, or PDE5Is. By inhibiting her PDE5, these drugs can widen blood vessels in certain parts of the body, especially the penis. Sildenafil was originally developed to treat high blood pressure and chest pain, which is why it was found to be particularly effective in relieving erectile dysfunction. And so the little blue pill was born.
Although these drugs are synonymous with ED, they are also used for other indications. Some are approved to treat pulmonary hypertension, or high blood pressure in the pulmonary arteries. And scientists are studying them for other medical uses. human and animal.
But the most interesting potential of these drugs may be their potential against Alzheimer's disease. 2021 NIH-funded study found Based on insurance claims data, there is evidence from the laboratory and real world that sildenafil may significantly prevent or delay the onset of Alzheimer's disease in older adults, possibly compared to not taking the drug. Potentially reduce relative risk by up to 69%. But less than a year later, an October 2022 study by another team (also funded by the NIH) that looked at Medicare data was published. not found Association between reduced Alzheimer's disease risk and sildenafil.
This contradictory finding was enough to catch the attention of epidemiologist Ruth Brower and her team at London College. So they decided to investigate on their own, using medical record data collected through the UK's National Health Service. Brauer said the data compared favorably to previous studies.
“UK health data can often be tracked over very long periods of time, longer than US insurance data. That is because most of our data is collected by general practitioners and primary care doctors, and they often have been treating patients for decades,” she explained. “A second feature of UK health data is that the data set includes a large number of lifestyle variables that can influence Alzheimer's risk. It's not just things like smoking or BMI, but social It also includes information about economic status.”
Brauer's team analyzed data from 269,725 elderly male residents (average age 59 years) with newly diagnosed erectile dysfunction, whether or not they were prescribed a PDE5I. He then tracked the results of the two groups for an average of five years.
In total, 1,119 people were diagnosed with Alzheimer's disease by the end of the study period. However, people who are tested for PDE5I are significantly less likely to develop Alzheimer's disease than those who are not tested, and after adjusting for other potentially important factors, the odds are about 18% lower. Ta. This reduced risk was clearly seen only with sildenafil and not with other PDE5Is, but this discrepancy may be due to fewer users of these drugs and not biological differences. Yes, Brauer said.
The team's findings show that published A 2021 study with these drugs suggested a more modest benefit, Wednesday in the journal Neurology. But Brauer's team was somewhat surprised that they found a buffer at all, given that they used a similar method to the 2022 study. The different results may be explained by the longer-term follow-up data her team had on hand, she says, and she certainly thinks this study could be showing some truth. He said there was.
“It's interesting that this protective effect was found in a study that tried to tightly control all the variables that could influence Alzheimer's risk,” she said.
Important questions remain unanswered about this link, including how exactly these drugs work to prevent or delay Alzheimer's disease. They are known to relax blood vessels, so they may improve blood flow in the brain enough to have a neuroprotective effect, Brauer said. Based on animal data, they may also indirectly increase levels of acetylcholine, a neurotransmitter important for cognition, which is reliably reduced in Alzheimer's patients (many Alzheimer's drugs Slowing this decline can help manage symptoms, but it cannot be stopped.)
Importantly, neither Brauer's study nor any other studies to date have provided conclusive evidence that PDE5Is can prevent Alzheimer's disease. But given the urgent need for drugs that can prevent the devastating condition or even slow its progression, these drugs deserve closer and broader investigation by other researchers, the authors say. states.
“Of course, the best way is to look at the association with randomized controlled trials,” she says. Ideally, the trial would study both men and women diagnosed with mild cognitive impairment, she added. Participants will be randomly assigned to receive PDE5I in combination with standard Alzheimer's disease treatment or standard treatment and a placebo, and then cognitive outcomes will be tracked over time.
“We believe that such trials will provide a comprehensive understanding of the potential therapeutic benefits of these PDE5Is,” she said.
