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).
Check cholesterol and vision yearly in adults with Down syndrome—treating these may lower dementia risk.
01Research in Context
What this study did
Shintaro and colleagues asked 133 Japanese adults with Down syndrome about their health. They wanted to know how many already had dementia and what daily habits or medical problems might raise the risk.
The team used a short survey and medical records. They looked at age, heart health, eyesight, and other factors that staff or families can change.
What they found
About one in three adults had dementia. The older the person, the more likely the diagnosis.
Two new red flags showed up: high cholesterol and poor vision. Both can be treated, so catching them early gives families a chance to act.
How this fits with other research
Howlin et al. (2006) already showed that extra words slipped into memory tests come before steep memory loss in Down syndrome. Takenoshita et al. (2026) now add clear medical risks you can measure in any clinic.
Tyrer et al. (2009) found sky-high cholesterol in older adults with intellectual disability. The new study narrows the warning to the Down syndrome group and links the same problem to dementia, not just heart disease.
Ekas et al. (2011) saw doubled high-cholesterol rates in young adults with autism. Together these papers tell us to screen lipids across developmental disabilities, not just Down syndrome.
Why it matters
You can add two quick checks to annual plans: a cholesterol blood test and a vision chart. Both take minutes, cost little, and open doors to treatment that may delay dementia. Share the numbers with caregivers so they can schedule eye exams and heart-healthy meals. Small moves now can buy years of clearer thinking later.
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02At a glance
03Original abstract
BACKGROUND: People with Down syndrome (DS) have a strong genetic predisposition to Alzheimer's disease (AD). However, the clinical burden and associated risk factors in diverse, non-Western populations remain less understood. This study aimed to investigate the prevalence of dementia in Japanese adults with DS and to identify modifiable clinical factors associated with dementia. METHODS: This cross-sectional multicentre study surveyed 133 adults with DS (mean age 50.1 years) residing in 45 welfare facilities across Japan in 2019. Dementia was diagnosed by a consensus panel of physicians using established criteria (DSM-5, ICD-10, DC-LD) after comprehensive assessments, including the Japanese version of the Dementia Screening Questionnaire for Individuals with Intellectual Disabilities (DSQIID-J). Logistic regression analysis was performed to identify factors independently associated with dementia. RESULTS: Forty-six participants (34.6%) were diagnosed with dementia. The prevalence rose sharply with age: 0% in their 30s, 30.8% in their 40s, 31.6% in their 50s and 65.5% in their 60s. After adjusting for covariates, older age, female sex, dyslipidaemia and visual impairment were independently associated with dementia. CONCLUSIONS: This study, the largest of its kind in Asia, confirms a high prevalence of dementia in institutionalized Japanese adults with DS. Crucially, this study is the first to identify dyslipidaemia and visual impairment as independent and potentially modifiable risk factors in this population. These findings highlight tangible targets for clinical interventions aimed at mitigating dementia risk in people with DS.
Journal of intellectual disability research : JIDR, 2026 · doi:10.1111/jir.12788