Ethnic Variation in Modifiable Risk Factors for Dementia

Abstract

AbstractBackgroundWe aimed to estimate the population attributable fraction (PAF) of 12 modifiable risk factors (defined by the Lancet Commission 2020), for incident dementia cases in the UK Biobank (UKB), stratified by ethnicity. We considered if ethnic differences in dementia risk, were accounted for by modifiable risk factors. To identify appropriate priorities in dementia prevention, tailored to ethnicity.MethodThe UKB is a cohort study with 502,656 volunteer participants registered between 2006‐2010, aged 40‐60 years at baseline, and followed for up to 16.8 years. To estimate the PAF of 12 modifiable risk factors (diabetes, hypertension, depression, hearing loss, obesity, traumatic brain injury (TBI), less education, social isolation, physical inactivity, air pollution, and smoking), we first estimated hazard ratios (HRs)(adjusted for age, gender, and Townsend quintiles), or when ethnicity interacted with risk factors, then we estimated HRs stratified by ethnicity. HRs were then converted to relative risk for PAF calculation.Results6,624 incident cases of dementia developed in 1.3%(95%CI = 1.3‐1.3)(n = 6316/471297){of Whites}, in 1.3%(95%CI = 1.1‐1.5)(n = 104/8031){of Blacks}, and in 1.0%(95%CI = 0.8‐1.2)(n = 79/8001){of South Asians (S.Asian)}. The mean age at dementia diagnosis was 71.6 years(SD,6.1){in S.Asians}; 71.8 years(SD,6.8){in Blacks}; and 73.6 years(SD,5.5){in Whites}. The combined PAF(95%CI) for dementia were: 35.6%(35.5‐35.8){in Whites}, 33.9%(32.8‐34.9){in Blacks}, and 41.0%(39.9‐42.0){in S.Asians}. The highest individual PAFs in each ethnic group, compared to the rest, were as follow. Blacks and S.Asians, respectively, for midlife hypertension: 9.6%(9.0‐10.3) and 10.1%(9.5‐10.8) vs 6.5%(6.4‐6.5){in Whites}. S.Asians for (1)Depression: 8.5%(7.9‐9.1) vs 4.0%(3.6‐4.4){in Blacks}, and 5.8%(5.7‐5.9){in Whites}; (2)Diabetes: 6.0%(5.4‐6.5) vs 5.1%(4.6‐5.6){in Blacks}, and 3.5%(3.4‐3.5){in Whites}; (3)Excessive alcohol: 1.4%(1.2‐1.7) vs 0.0%{in Blacks and Whites}. Whites for (1)Hearing loss: 3.6%(3.6‐3.7) vs 2.4%(2.1‐1.8){in Blacks}, and 3.0%(2.6‐3.4){in S.Asians}; (2)TBI: 2.5%(2.4‐2.5) vs 1.3%(1.1‐1.6){in Blacks}, and 1.7%(1.4‐2.0){in S.Asians}; (3)Less education: 5.0%(4.9‐5.1) vs 3.3%(2.9‐3.7){in Blacks}, and 3.2%(2.9‐3.6){in S.Asians}; (4)Physical inactivity: 2.6%(2.6‐2.7), vs 2.1%(1.8‐2.5){in Blacks}, and 2.2%(1.8‐2.5){in S.Asian; (5)Social isolation: 2.3%(2.2‐2.3) vs 1.9%(1.6‐2.1){in Blacks}, and 1.9%(1.6‐2.2){in S.Asians. The remaining risk factor PAFs did not differ between all ethnic groups.ConclusionIn this relatively wealthy, and healthy population, there remain ethnic disparities in the effect of modifiable risk factors on dementia. Interventions for midlife hypertension are a priority in South Asians and Blacks, particularly depression and alcohol consumption in South Asians.