Temporal comorbidity patterns in Alzheimer’s disease and vascular dementia: a population-based observational study inn UK Biobank

Introduction: In Alzheimer’s Disease and Vascular Dementia, comorbidities shape disease trajectories and care needs, yet their timing across the lifespan remains poorly understood. Methods: We analysed comorbidities using in-patient hospital ICD-10 codes in 10,730 UK Biobank participants with Alzheimer’s Disease or Vascular Dementia, spanning 20 years before to 10 years after diagnosis. Logistic regression and Bayesian Network Analysis identified time- and subtype-specific risk patterns, validated against controls. Results: Distinct comorbidities emerged decades before diagnosis. In Alzheimer’s Disease, depressive episodes, osteoporosis, and type 1 diabetes appeared up to 20 years pre-diagnosis, while Vascular Dementia was characterised by early cerebral infarctions, type 1 diabetes, intestinal disorders, and rheumatoid arthritis, absent in controls. Discussion: Although restricted to severe populations captured in in-patient data, excluding primary care, these findings reveal time-dependent prodromal patterns in Alzheimer’s Disease and Vascular Dementia, highlighting opportunities for targeted screening, prevention, and early intervention.