FIESTA: A trial to investigate whether tadalafil is safe, and can slow progression, in Alzheimer’s disease

What is the aim of the study? 

To investigate whether a drug called tadalafil is safe to be used in patients with mild Alzheimer’s disease and whether it helps slow progression. Tadalafil is a drug that has been on the market for around 20 years. It has previously been used to treat a heart condition called pulmonary hypertension and is also used to treat 
erectile dysfunction. It has been noted in the past that tadalafil may be associated with a lower risk of memory issues such as Alzheimer’s, possibly by increasing blood flow to the brain and reducing inflammation. We want to test this theory formally in a large research trial.  

What will participants be asked to do during the study? 

Participants will be asked to attend for a screening visit. The screening visit will involve memory tests and blood tests. If accepted onto the trial, there is a baseline visit. Here, we do more comprehensive memory tests and 3 different types of scans (MRI, DCE-MRI, and PET-CT). There is an option to have a lumbar puncture (a needle into the back to sample brain fluid), but this is optional.  After this, participants will be randomised to either tadalafil or a dummy pill (placebo). Participants will have a 50% chance of being on tadalafil vs placebo. Find more information about why studies use blinding, randomisation and placebo controls.

Participants will take the tablets for a year. There will be multiple visits to check up on participants - at 2 weeks (over the phone), 1 month, 3 months, 6 months, 9 months, and 12 months. Blood pressure will be monitored carefully, because tadalafil can sometimes cause low blood pressure.  

After a year, participants will finish their medication and the scans (MRI, DCE-MRI and PET-CT), memory tests and blood tests will be repeated.  
In total, there will be around 8 visits.