Prevalence of dementia diagnosis in Sweden by geographical region and sociodemographic subgroups: a nationwide observational study.

Background: Although dementia incidence has decreased in high-income countries, it is important to monitor the prevalence of dementia and identify potential underdiagnosis in population subgroups. This study provides the most up-to-date prevalence of dementia diagnosis in Sweden, by geographical regions and sociodemographic groups. Methods: We identified all individuals aged ≥62 years, registered and alive in Sweden at the end of 2022 (n = 2.48 million). Dementia diagnoses were identified using ICD-9/10 codes in the National Patient Register since 1987, as well as anti-dementia drug use from the Prescribed Drug Register since 2005. Findings: At the end of 2022, 3.7% (92,293/2,483,798) of people aged ≥62 years in Sweden had a dementia diagnosis from specialist care or drug prescriptions and varied from 0.6% in ages 62-69 to 14.8% in ages ≥90. The prevalence of cognitive impairment diagnosis was 2.5%. There was some geographical variation in the prevalence of dementia diagnosis, with a larger proportion of diagnoses coming from drug prescriptions than from specialist care in northern Sweden. While people born abroad and people without a close relative had a slightly higher prevalence of dementia diagnosis than Swedish born and those with close relatives, the prevalence was substantially lower for people living alone than for cohabiting individuals. Interpretation: Comparing case estimates from previous screening cohorts, our results suggest underdiagnosis of dementia in the general older population, particularly among people who live alone. In more rural areas with lower availability of memory clinics, primary care may play an important role in diagnosing older adults with dementia. Funding: Swedish Research Council for Health, Working Life and Welfare; Swedish Research Council; Region Stockholm.