This study consist of three sub-studies.~In study 1, participants diagnosed with mild cognitive impairment due to AD or mild to moderate AD will be followed for up to 24 months with repeated blood samples, pupillometry, actigraphy, cognitive tests and a control brain scan.~In study 2, patients under investigation of a neurodegenerative disease who have a planned lumbar puncture in the Memory clinic will be invited to this study. Participants will undergo pupillometry and blood samples two times approximately one and four weeks after the lumbar puncture.~In study 3, participants with a dementia diagnosis will undergo pupillometry and actigraphy at a single visit.
This study will investigate the efficacy of novel biomarkers, namely blood-based biomarkers, pupillometry and actigraphy to track and predict progression of Alzheimer's disease (AD). Furthermore, the study will investigate the diagnostic value of pupillometry and actigraphy for AD.