Prevalence of dementia in a semi-urban population in Sri Lanka: report from a regional survey

Background The prevalence of dementia in Sri Lanka, which has a rapidly ageing population, is unknown. Objective This study aimed to determine the prevalence of Alzheimer's disease (AD) and other dementias in a semi-urban elderly Sinhala-speaking population in Ragama, Sri Lanka. Methods The study was conducted in two phases. Phase I: After informed consent 703 subjects aged greater than or equal to65 years from the study area (population 15 828) were screened for cognitive impairment using the Sinhalese Mini Mental State Examination. Subjects scoring less than or equal to17 were regarded as suspected dementia cases. Phase II: All subjects who screened positive in phase I were included in phase II for detailed evaluation for dementia according DSM IV and NINCDS-ADRDA criteria which included structured neuropsychiatric assessment, laboratory investigations, an axial CT scan of the brain and an informant interview. Results In the study sample, 61% were female and 86% were between 65-75 years. 42 subjects screened positive in phase I. Of these, 28 subjects were diagnosed as having dementia, giving an overall prevalence rate of 3.98% (95% Confidence Intervals (CI) = 2.6-5.7%). Of these, 20 (71.4%) had probable AD, four had vascular dementia (14.3%), two had mixed (vascular and AD) dementia (7.1%), one had Lewy body dementia, and one had dementia due to syphilis. Greater age, illiteracy and female gender were associated with higher prevalence of dementia. Conclusion Comparison with other community studies performed in North India suggests that dementia prevalence is higher in Sri Lanka. This may be due to regional differences in disease incidence. Copyright (C) 2003 John Wiley Sons, Ltd.