Cerebral small vessel disease is a progressive brain and blood vessel disease for which there currently is no effective treatment. The disease associates with 25 % of all stroke and 30 % of all dementia cases and imposes a major and increasing health burden worldwide. In this trial the investigator suggest a new promising solution to this problem.~Patients with cerebral small vessel disease, who experience stroke or vascular dementia, may show reduced brain perfusion or altered neurovascular reactivity. The investigator has previously shown that a single dose of tadalafil (20 mg), shortly increased blood supply to the brain in patients with cerebral small vessel disease. This holds promise for new effective treatment targets. The investigator test if patients find three months daily intake of tadalafil (20 mg) feasible, and if it alters cerebral perfusion, neurovascular reactivity, and cognition, including memory and planning ability. The trial will help identify new treatment targets to reduce the number of patients with stroke, stroke sequelae, and vascular dementia.~This trial is divided into one main study and three sub studies:~Main study~Dynamical MRI sub study~Cognitive sub study~Biomarker sub study
In a randomized controlled trial the feasibility and effect of three months treatment with daily tadalafil, on cerebral blood flow/reactivity and cognition, is investigated in patients with cerebral small vessel disease.