Healthcare utilization prior to a diagnosis of young-onset Alzheimer’s disease: a nationwide nested case–control study

OBJECTIVE: Our aim was to identify changes in healthcare utilization prior to a young-onset Alzheimer’s disease diagnosis. METHODS: In a retrospective incidence density matched nested case–control study using national health registers, we examined healthcare utilization for those diagnosed with young-onset Alzheimer’s disease in Danish memory clinics during 2016–2018 compared with age- and sex-matched controls. Negative binomial regression analysis produced contact rate ratios. RESULTS: The study included 1082 young-onset Alzheimer’s disease patients and 3246 controls. In the year preceding diagnosis, we found increased contact rate ratios for all types of contacts except physiotherapy. Contact rate ratios for contacts with a general practitioner were significantly increased also > 1–5 and > 5–10 years before diagnosis. The highest contact rate ratios were for psychiatric emergency contacts (8.69, 95% CI 4.29–17.62) ≤ 1 year before diagnosis. INTERPRETATION: Results demonstrate that young-onset Alzheimer’s disease patients have increased healthcare utilization from 5 to 10 years prior to diagnosis. Awareness of specific alterations in health-seeking behaviour may help healthcare professionals provide timely diagnoses. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00415-023-11974-x.