A Cross-Sectional Study of Potentially Modifiable Risk Factors for Dementia and Cognitive Function in India

Background: Dementia is rising globally, particularly in low-and-middle-income countries. India has almost four million people living with dementia, set to double by 2050. Targeting nine potentially modifiable risk factors (less education, hearing impairment, depression, physical inactivity, hypertension, obesity, smoking, diabetes, and social isolation) could possibly prevent or delay many dementias. We aimed for the first time to examine risk factors for dementia in India and their link with cognitive status and dementia, to inform prioritisation of public health interventions that could prevent or delay dementia. Methods: We conducted a cross-sectional analysis using three studies: 10/66 Dementia Study (n= 2,004), Longitudinal Aging Study of India (n= 386), and Study of Global Ageing (n= 2,441). Our exposures were the nine risk factors above. We calculated a cognitive z-score within each study and used dementia diagnosis in 10/66. We adjusted for socioeconomic factors, age, and sex using multivariable linear for cognition and logistic regression for dementia. Findings: Less education, hearing impairment, depression, and physical inactivity were associated with lower z-scores and increased odds of dementia. Obesity was associated with higher z-score and lower odds of dementia. Social isolation was associated with lower z-scores and decreased odds of dementia. Results for smoking, diabetes, and hypertension were inconsistent. Interpretation: Our risk estimates were larger for less education, hearing impairment and physical inactivity compared to global estimates and should be intervention priorities. This study highlights the need for longitudinal studies to clarify the relationship between these potentially modifiable risk factors and dementia in India. Funding Information: CBR is supported by a National Institutes of Health Research (NIHR) Academic Clinical Fellowship, NM by an Alzheimer’s Society Senior Fellowship, GL by North Thames NIHR ARC and an NIHR senior investigator award. GL and NM are supported by the NIHR Biomedical Research Centre. Declaration of Interests: The authors have no interests to disclose. Ethics Approval Statement: This was a secondary analysis of existing data. Ethics committee approval was sought by each individual study. We received agreement to use this data on 3rd October 2019 and downloaded the data dictionary, questionnaires and assessment tools.