Dag Aarsland focuses on studies of cognitive decline in Parkinson’s disease and dementia with Lewy bodies (DLB), and he leads longitudinal cohort studies and clinical trials. He is the principal investigator of the European DLB Consortium and various DLB cohort studies, including ENLIST in the UK and a study in Norway. He chaired the ISTAART Professional Interest Group for Lewy body dementias. Collaborating with Dr. Richard Killick, he has explored the role of the Wnt signaling pathway in neurodegeneration, securing grant funding to study the ability of fasudil to block the neurotoxicity induced by aberrations in Wnt signaling in Alzheimer's disease. Together they aim to gather evidence for a fasudil clinical trial in DLB, emphasizing the importance of understanding tau,  amyloid b, and alpha-synuclein pathologies.