(Alzheimer's) dementia in adults with Down syndrome in Germany: Administrative prevalence based on a claims data analysis.

BackgroundPeople with Down syndrome (DS) have a significantly increased risk of developing early-onset Alzheimer's disease. For example, a longitudinal study by McCarron et al. (2017) found that 97% of a cohort of 77 DS patients aged 35 years and older developed dementia. Despite this high risk, administrative data on dementia prevalence in this population remain limited.ObjectiveThis study examines whether the diagnosed prevalence is lower than expected based on epidemiological data and explores differences compared to the general population.MethodsA comparative analysis of administrative dementia prevalence (2010-2019) was conducted using claims data for adults with and without DS. Prevalence rates were calculated by age and sex. Chi-square tests were applied to assess significance (p < 0.05), with Cramér's V and Phi as measures of association. Odds ratios were calculated to evaluate group differences.ResultsTotal administrative dementia prevalence was significantly higher in adults with DS (Mean Value (MV) 9.2% ± 1.7% (Standard Deviation (SD))) than those without DS (MV 3.2% ± 0.3% (SD)). Age- and sex-specific analyses also revealed notable differences. For example, in the 56-60 years age group, prevalence was MV 28.7% ± 4.6% (SD) in adults with DS versus MV 0.7% ± 0.1% (SD) in those without DS.ConclusionsAlthough administrative dementia prevalence is higher among adults with DS than those without DS, observed rates appear lower than expected based on existing epidemiological data. This suggests a potential underdiagnosis of dementia in the DS population in Germany.