Prevalence and Modifiable Risk Factors of Dementia in People With Down Syndrome: Cross-Sectional Study of Japan in Collaboration With the Intellectual Diversity for Goodness Research Consortium (INDIGO-2019).

The study included only facility residents, most of whom had severe to profound intellectual disability. Results may not apply to people with Down syndrome living in the community or with milder disabilities. Dementia was assessed using observer-rated scales and clinical consensus rather than objective cognitive tests, which may miss early or mild cases. Comorbidity data (like dyslipidaemia and visual impairment) were taken from existing medical records without new examinations, so the accuracy and severity of these conditions were not verified. The cross-sectional design cannot prove that dyslipidaemia or visual impairment caused the dementia; they may be markers of other processes. The study did not use biomarkers (like amyloid PET scans or blood tests), so the biological subtype of Alzheimer's disease was not confirmed.

The study was supported by the Nippon Foundation and JSPS KAKENHI. The authors declared no conflicts of interest, and the funders had no role in the design or conduct of the study.

Do not assume that treating dyslipidaemia or correcting vision will prevent dementia. This study shows an association in a specific group of institutionalised adults with severe intellectual disability, but it cannot prove cause and effect or generalise to community-dwelling individuals with milder disabilities.