Multi‐ethnic differences in brain and biopsychosocial risk factors for ADRD in UK immigrants from the Middle East and North Africa (MENA)

Abstract

AbstractBackgroundThe populations of the Middle East and North Africa countries (MENA) are predicted to contribute to the world’s sharpest increases in rates of Alzheimer’s disease and related dementias (ADRD) in the coming years (GBD 2022), yet this group is underrepresented in health studies. The UK Biobank provides one of the largest and well‐characterized datasets on aging immigrants in the UK. We compare risk factors for ADRDs between UK immigrants from MENA countries to those of immigrants from other countries.MethodImmigrants from MENA countries (N = 3557), India (N = 2959), Germany (N = 1103), and genetically‐determined British individuals (N = 1929) born outside of the UK in any of the three areas of interest were included in the study. There are multiple definitions of MENA: here, MENA was defined broadly to include the union of all included countries; Figure 1 highlights the distribution in this sample. We focused on variables associated with suboptimal brain aging and ADRD risk: APOE genotypes; education; an algorithmically defined diet quality score (Zhuang, 2021); BMI; incidence of parental death before 65 years; and the Townsend deprivation index (TDI) as a proxy of socioeconomic status (SES). Chi‐squared or Mann‐Whitney tests provided statistics on distribution discrepancies for categorical or continuous data, respectively. We also charted hippocampal volumes with age for the subset of each ethnic group who underwent neuroimaging.ResultFigure 2 highlights group demographics and distributions. Compared to all other groups (Figure 3), MENA groups had higher TDI (lower SES), lowest diet quality, and highest BMIs; these differences remained even in college educated individuals. MENA also reported a greater incidence of maternal deaths before age 65. German immigrants were more highly educated than all other groups. ApoE4 alleles were significantly less prevalent in MENA and Indian countries than groups of European ancestry (Figure 4). Hippocampal volumes, adjusted for intracranial volume, had similar age‐trends across groups.ConclusionMany ADRD risk factors differ substantially across different ethnic groups, even when the proportion with a college education is not different. It is imperative to understand underlying lifestyle and sociological factors associated with immigration, to provide adequate healthcare for all aging individuals.