Prevalence and Risk Factors for Cognitive Impairment and Dementia in Indians: A Multiethnic Perspective from a Singaporean Study

Article type: Research Article

Authors: Wong, Mark Yu Zheng^a | Tan, Chuen Seng^b | Venketasubramanian, Narayanaswamy^c | Chen, Christopher^d | Ikram, M.K.^e | Cheng, Ching-Yu^{f; g; h} | Hilal, Saima^{a; d; *}

Affiliations: [a] Memory Ageing and Cognition Center (MACC), National University Health System, Singapore | [b] Saw Swee Hock School of Public Health, National University of Singapore, Singapore | [c] Raffles Neuroscience Centre, Raffles Hospital, Singapore | [d] Department of Pharmacology, National University of Singapore, Singapore | [e] Departments of Epidemiology and Neurology, Erasmus University Medical Center, Rotterdam, The Netherlands | [f] Singapore Eye Research Institute, Singapore | [g] Academic Medicine Research Institute, Duke-NUS Medical School, Singapore | [h] Singapore National Eye Centre, Singapore

Correspondence: [*] Correspondence to: Saima Hilal, MD, PhD, Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Level 4, Block MD3, 16 Medical Drive, Singapore 117600. Tel.: +65 65165885; Fax: +65 68737690; E-mail: phchs@nus.edu.sg.

Abstract: Background:Dementia is the leading cause of dependency and disability among older persons worldwide. There remains, however, limited studies on dementia rates within the Asia-Pacific region, with little data on differences across major Asian ethnic groups. Objective:To study the prevalence of cognitive impairment (CI) and dementia in community-dwelling Indians from Singapore and to examine interethnic differences among Chinese, Malays, and Indians. Methods:Participants (>60 years) drawn from the Indian component of the multiethnic Epidemiology of Dementia in Singapore (EDIS) study were screened using the locally validated Abbreviated Mental Test and Progressive Forgetfulness Questionnaire. Screen-positive participants underwent further detailed neuropsychological assessments. CI was classified into Cognitive impairment no dementia (CIND)-mild, CIND-moderate, and dementia. Results:Of 961 Indian adults, 120 (12.5%) had CIND-mild, 101 (10.5%) CIND-moderate, and 12 (1.2%) dementia. The overall age-standardized prevalence of any CI was 24.6%. The prevalence of any CI increased with age (15.7% in ages 60–64 years to 30.1% in ages≥80 years), and was higher in women than men. Multivariate analysis showed that age, lower education, and hypertension were independently associated with CI. Even after demographic and cardiovascular risk factor adjustment, Indians were more likely to be cognitively impaired compared to Chinese (odds ratio [OR], 95% CI:1.37 [1.01–1.86]) but not Malays (0.89 [0.72–1.10]). Conclusions:Among elderly Indians, the overall prevalence of any CI was 24.6%. Despite similar assessment protocols and risk factor adjustments, the prevalence of CI was higher in Indians compared to Chinese but similar to Malays. Further research is needed to unravel other factors that may underlie these ethnic differences.

Keywords: Cognitive impairment, dementia, epidemiology, Indian, prevalence, population-based, risk factors

DOI: 10.3233/JAD-190610

Journal: Journal of Alzheimer's Disease, vol. 71, no. 1, pp. 341-351, 2019