Opposing trends in early-onset dementia incidence across subtypes in Finland, 2016–2024

Background

Early-onset dementia (EOD) poses a major public health and economic challenge. Epidemiological studies have shown heterogenous incidence and prevalence rates due to varying inclusion criteria and data sources. Using comprehensive register data covering Finnish adult population and all health care sectors, we estimated the annual incidence of EOD, including subtypes, in Finland during 2016–2024. We also estimated the prevalence of EOD and the distribution of diagnoses in specialized, primary, and private sectors in 2024.

Methods

This retrospective observational nationwide register-based study included new EOD cases in individuals aged 30–64 years during 2016–2024. Data were obtained from the Finnish Care Register for Health Care and the Register of Primary Health Care Visits, compiled with medication purchase data. Dementia diagnoses were identified using ICD-10 and ICPC codes, supplemented by records of anti-dementia medication use. Prevalence rate in 2024, and annual incidence rates were calculated using population statistics.

Results

In 2024, the age- and sex-standardized incidence rate of EOD was 42/100,000, and the prevalence was 256/100,000. Alzheimer’s disease was the most common diagnosis (38%), followed by unspecified (21%), frontotemporal (11%), and vascular dementias (11%). The trend of EOD incidence remained stable in 2016–2024. The incidence of alcohol-related dementias decreased markedly, while Alzheimer’s disease, vascular and frontotemporal dementias showed an increasing trend. Approx. 72% of EODs were diagnosed in specialized health care, 18% in primary care, and 10% in private sector.

Conclusions

The overall incidence and prevalence of EOD seem to be higher than previously reported when considering all dementia subtypes and all health care providers. Underestimation of incidence could lead to insufficient resources. Strengthening collaboration across health care sectors could integrate diagnostic services in people with EOD.

Key messages

• The incidence and prevalence of early-onset dementia (EOD) seem to be higher than previously reported. Alcohol-related dementia incidence is decreasing, while other common subtypes are increasing.

• Even though the majority of EODs are diagnosed in specialized health care, over one quarter are diagnosed in primary care or the private sector, which calls for cross-sector coordination.