ODIN Biobank: a Danish cohort for dementia research- cohort profile.

PURPOSE: Biomarkers related to the diagnosis, prognosis and treatment of dementia will play a key role in future clinical practice. The overarching aim of the ODIN (blood and cerebrospinal fluid) Biobank is to study biomarkers for dementia and contribute to the transition from cerebrospinal fluid to blood-based biomarkers. PARTICIPANTS: ODIN recruited 451 patients (median age 74 years, 53% females) referred to the Department of Neurology at Aarhus University Hospital, Denmark, for diagnostic assessment of dementia. Enrolment started in March 2020 and ended in July 2025. Patients referred for a lumbar puncture were eligible for inclusion. Cerebrospinal fluid and blood samples (plasma, serum and buffy coat) were stored at -80°C. Information about sociodemographic, educational level, dementia subtype, cognitive test scores, neuroimaging results, hypertension, diabetes, height, weight, alcohol consumption and smoking was collected. FINDINGS TO DATE: The most frequent diagnoses were Alzheimer's disease (n=268, 59%), frontotemporal dementia (n=26, 5.8%) and mixed Alzheimer's and vascular disease (n=23, 5.1%). N=82 (18%) were cognitively unimpaired or had mild cognitive impairment but not dementia. The median Mini-Mental State Examination score was 23 (IQR: 20-26) and the median Addenbrooke's Cognitive Examination score was 68 (IQR: 58-77). FUTURE PLANS: ODIN will contribute to the development, validation and implementation of new biomarkers related to diagnosis, prognosis and treatment of dementia. Furthermore, the cohort will assist the transition from cerebrospinal fluid to blood-based biomarkers.