Ethnic differences in Singapore's dementia prevalence: the stroke, Parkinson's disease, epilepsy, and dementia in Singapore study.

OBJECTIVES

To study the prevalence of dementia in Singapore among Chinese, Malays, and Indians.

DESIGN

A two-phase, cross-sectional study of randomly selected population from central Singapore with disproportionate race stratification.

SETTING

Community-based study. Subjects screened to have cognitive impairment at phase 1 in their homes were evaluated clinically for dementia at phase 2 in nearby community centers.

PARTICIPANTS

Fourteen thousand eight hundred seventeen subjects aged 50 and older (67% participation rate).

MEASUREMENTS

The locally validated Abbreviated Mental Test was used to screen for cognitive impairment at phase 1. Dementia was diagnosed at phase 2 as per Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria. Possible Alzheimer's disease (AD) and possible vascular dementia (VD) were diagnosed along the National Institute of Neurological and Communicative Disorders-Alzheimer's Disease and Related Disorders Association and National Institute of Neurological Disorders and Stroke-Association Internationale pour la Recherche et l'Enseignement en Neuroscienes criteria, respectively.

RESULTS

The overall age- and race-standardized dementia prevalence was 1.26% (95% confidence interval (CI)=1.10-1.45). Prevalence (in 5-year age bands) was 0.08% (50-54), 0.08% (55-59), 0.44% (60-64), 1.16% (65-69), 1.84% (70-74), 3.26% (75-79), 8.35% (80-84), and 16.42% (>/=85). From age 50 to 69, 65% of dementia cases were VD; at older ages, 60% were AD. Logistic regression (adjusted for age, sex, education) showed that Malays had twice the risk for AD as Chinese, and Indians had more than twice the risk for AD and VD than Chinese.

CONCLUSION

Singapore's dementia prevalence, primarily influenced by its Chinese majority, is lower than seen in the West. The striking interethnic differences suggest a need for a dementia incidence study and further investigation of underlying genetic and cultural differences between the three ethnic groups in relation to dementia risk.