DEDEMAS/DEMDAS is an observational hospital-based study investigating the long-term cognitive outcomes in a cohort of stroke patients from Germany. Patients without pre-stroke dementia, who experienced an acute stroke within 5 days of joining the study were enrolled from 7 stroke centres across Germany. The study began as a single-centre pilot study (DEDEMAS) in Munich, Germany, which enrolled 136 patients between May 2011 and November 2013 and was subsequently expanded to a multicentre study (DEMDAS) which enrolled an additional 600 patients between January 2014 and January 2019. The patients are followed up for 5 years following the acute stroke, with assessments at baseline, 3 months, 6 months, 12 months, and every 12 months following this. The participants will also have an annual follow up from year 6-10.