5. Investigate the underlying disease mechanisms of dementia disorders in humans aiming at finding new relevant drug targets. Drug discovery using the currently available cell and animal models, has not translated to human research as indicated by failed phase II and III trials. There are several possible reasons for these failures. First, it is possible that previous trials may have focused on the wrong drug targets, since findings from cell and animal models of dementias may not have accurately captured essential aspects of the disease mechanisms in humans. BioFINDER2 will be a translational study where we will attempt to bridge the knowledge gap between cell/animal studies and studies in humans, by using biomarkers that reflect biological mechanisms that may be studied across model systems. Second, another reason of the failed trials may be that they included patients in too advanced disease stages for the treatments to be effective, or that they partly included patients with unspecific diseases, since they did not use biomarker-based methods for inclusion of participants. BioFINDER2 will inform on the design of future clinical trials by providing detailed data about cognitive and functional changes over time in people with well-defined biomarker-characterized brain pathologies.