Prevalence of dementia in a semi-urban population in Sri Lanka

Abstract

BACKGROUND: The Sri Lankan population is aging rapidly. However, the prevalence of dementia, a devastating disease of the elderly, is unknown. Methods: A community survey to assess the prevalence of dementia in a semi-urban population was done in the Gampaha district. The study was conducted in two phases. Phase I: after informed consent 703 randomly selected subjects over 65 years from four PHM areas in Ragama (population 15828) were screened for cognitive impairment using the Sinhala Mini Mental State Examination (MMSE). Subjects scoring <17 were regarded as suspected dementia cases. Phase II: all subjects who screened positive in phase I were included in phase II for detailed evaluation of dementia according to DSM IV and NINCDSADRDA criteria which included structured neuropsychiatric assessment, laboratory investigations, axial and temporal lobe-oriented CT scans of the brain and an informant interview. The average time interval between screening and detailed evaluation for 1 dementia was 7.7 months. RESULTS: 42 subjects screened positive in phase I. Of these, four died, one moved home and one suffered a stroke before detailed evaluation, and two did not consent. Two had psychiatric disease I and five had no evidence of dementia. 27 subjects [Mean age =71(6.37); M:F=8:19] were diagnosed as having dementia according to operative criteria. Of these, 19 (70.4%) had probable Alzheimer's disease (AD), three had vascular dementia (11.1 %), three had mixed (vascular and AD) dementia (11.1 %), one had Lewy body dementia, and one had dementia due to syphilis. CONCLUSIONS: In our study population, the prevalence rate of dementia is at least 3.8%, and the majority (66.6%) is of the Alzheimer type.