An epidemiologic study of mild cognitive impairment in Kolkata, India

Objectives: To estimate the prevalence of two types of mild cognitive impairment (MCI) - amnestic and multiple domain types -among nondemented and nondepressed elderly subjects aged 50 and older. Methods: The study was carried out in Kolkata, the eastern metropolis of India. A cross-sectional community screening was carried out, and 960 subjects were selected by systematic random sampling for the assessment of cognitive function with the help of a validated cognitive questionnaire battery administered through house-to-house survey. A case-control study was also undertaken to identify potential risk factors through univariate analysis. Results: Ultimately, full evaluation of cognitive function was possible in 745 of 960 subjects. An overall prevalence of MCI detected based on neuropsychological testing was 14.89% (95% CI: 12.19 to 17.95). Prevalence of the amnestic type was 6.04% (95% CI: 4.40 to 8.1) and that of the multiple domain type was 8.85% (95% CI: 6.81 to 11.32). Adjusted for age, education. and gender, the amnestic type was more common among men and the multiple domain type among women with advancement of age. Rates differed considerably with educational attainment. Hypertension and diabetes mellitus were the major risk factors for both types of MCI. Conclusion: In this first community-based study of mild cognitive impairment (MCI) from India, prevalence of the amnestic type is comparable with and that of the multiple domain type is less than the prevalence in developed countries. Variations in age, education, and gender specific prevalence of MCI of both types were encountered. The putative risk factors identified merit further study.