a Parkinson's disease feed — research, treatments, lived experience, in plain language
# # # # Analysing medical data at the national level can provide a means of screening for drugs that can have an impact on the progression of chronic diseases. The large datasets of millions of people offer the opportunity to see trends for particular drugs that could potentially point towards new avenues of research.
A large Norwegian observational study — analysing health registry data from 14,289 people diagnosed with Parkinson's — found that tadalafil (Cialis), a drug best known for treating erectile dysfunction and prostate symptoms, was among 23 medications associated with fewer deaths over an 8-year period. That finding made headlines, but the honest takeaway is: don't rush to the pharmacy. Observational studies show associations, not causes. The researchers themselves flag a likely explanation: men healthy enough to be prescribed tadalafil were probably healthier overall — which would explain their longer survival regardless of whether the drug helped their Parkinson's. The preclinical (lab and animal) evidence for PDE5 inhibitors like tadalafil or sildenafil (Viagra) slowing Parkinson's is thin, and one cell-study directly showed that sildenafil had no protective effect against alpha-synuclein toxicity — the protein clumping central to the disease.
If you or your partner already takes tadalafil for erectile dysfunction or prostate enlargement, this study gives no reason to stop — but it also gives no reason to start taking it as a Parkinson's treatment. People with Parkinson's should be aware that both tadalafil and sildenafil can lower blood pressure, which matters because many people with Parkinson's already have low blood pressure (orthostatic hypotension). Before using either drug, a clinician should check lying-down and standing blood pressure. The combination with levodopa also warrants care: a rodent study found that acute doses of sildenafil may amplify levodopa's motor effects in ways that could worsen involuntary movements (dyskinesia).
The more genuinely interesting thread in this article is about Alzheimer's disease, not Parkinson's. Two large insurance-record studies found that men who used PDE5 inhibitors had a meaningfully lower risk of developing Alzheimer's, and a small phase 2 trial of a purpose-built PDE5 inhibitor (AR1001) showed the drug was safe in dementia patients — though it did not hit its primary endpoints at 26 weeks. A phase 3 trial (Polaris-AD, 1,535 participants) is underway and expected to report in late 2026. That result will matter for anyone worried about cognitive decline alongside Parkinson's, but it is still early and not a treatment recommendation.