Potentially Modifiable Risk Factors, Ethnicity and Dementia: A UK Biobank Prospective Cohort Study of White, South Asian and Black Participants

Background: Our knowledge of potentially modifiable risks factors for dementia are from European origin populations. We aimed to explore if these risk factors had similar effects in United Kingdom (UK) White, South Asian and Black UK Biobank participants recruited from 2006-2010 and followed up until 2020. Methods: We reviewed the literature to 25.09.2020 for meta-analyses identifying potentially modifiable risk factors preceding dementia diagnosis by ≥ 10 years. We calculated prevalence of each identified risk factor and association with dementia for participants aged ≥ 55 at registration in UK biobank.  We calculated hazard ratios using Cox regression for each risk factor, stratified by ethnic group and tested for differences using interaction effects between each risk factor and ethnicity. Findings: We included education, hearing loss, hypertension, obesity, excess alcohol consumption, physical inactivity, smoking, high total cholesterol, depression, diabetes, social isolation, and air pollution as risks. Out of 294,725 participants, there were 287,806 White, 3590 South Asian and 2766 Black people, followed up for up to 14.8 years, with a total follow-up time of 3,392,095 years. During follow-up, 5,972 people developed dementia. Risk of dementia was higher in Black participants than White participants (HR 1.43, 95% CI 1.16-1.77, p=0.001) but South Asians had a similar risk. Association between each risk factor and dementia was similar in each ethnic group with no evidence of interaction effects. Interpretation: We find that Black participants were more likely to develop dementia than White participants, but South Asians were not. Identified risk factors in White European origin participants had a similar effect in Black and south Asian origin participants. Volunteers in biobank are not representative of the population and interaction effects were likely underpowered so further work is needed. Registration Details: We registered the protocol for this project online prior to data analysis (https://osf.io/d2j4z/). Funding Information: NM is funded by an Alzheimer’s Society Senior Fellowship (AS-SF-18b-001). We received no other funding for this research. Declaration of Interests: None to declare. Ethics Approval Statement: The UK Biobank received approval from the National Information Governance Board for Health and Social Care and the National Health Service North West Multicentre Research Ethics Committee. All participants provided informed consent through electronic signature at baseline assessment.