Migrant density associated with risk for nonaffective psychosis
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Migrant density may reduce risk for psychotic disorders among migrants and their children, according to results of a national, longitudinal cohort study conducted in Sweden and published in The Lancet Psychiatry.
“This research showed that neighborhood characteristics can influence the rates of psychotic disorders,” Jennifer Dykxhoorn, PhD, senior research fellow in public mental health at University College London, told Healio Psychiatry. “This is important because it suggests that the unequal distribution of psychotic disorders in migrant populations may be socially constructed.”
The researchers referenced the ethnic density hypothesis, which asserts that minority ethnic individuals residing in areas with higher proportions of people from their own ethnic groups experience improved health outcomes compared with those who reside in areas with lower ethnic density. Researchers have theorized that these outcomes might be linked to the protective effect of fewer discriminatory experiences and increased social support, but other explanations are possible, Dyxhoorn and colleagues noted.
To investigate whether living in areas of own-region migrant density reduced risk for psychotic disorders among migrants and their children, the researchers collected Swedish register data of migrants and their children born between 1982 and 1996. They tracked participants from age 15 years or date of migration until study end, death or emigration and used an ICD-10 diagnosis of nonaffective psychosis as the outcome. Using data from the 9,208 small areas for market statistics neighborhoods in Sweden, they calculated own-region and generation-specific own-region migrant density and then estimated the relationship between density and diagnosis of nonaffective psychotic disorders using multilevel Cox proportional hazard models, adjusted for neighborhood, individual and family confounders.
The final cohort included 468,223 individuals, of whom 4,582 (1%) had nonaffective psychotic disorder. Lower own-region migrant density was linked to increased risk for psychotic disorders among migrants (HR = 1.05; 95% CI, 1.02-1.07 per 5% decrease) and children of migrants (HR = 1.03; 95% CI, 1.01-1.06), after adjustment. Probable visible minority migrants (HR = 1.07; 95% CI, 1.04-1.11) experienced stronger effects, including those from Asia (HR = 1.42; 95% CI, 1.15-1.76) and sub-Saharan Africa (HR = 1.28; 95% CI, 1.15-1.44), but effects did not appear stronger for migrants from probable nonvisible minority backgrounds (HR = 0.99; 95% CI, 0.94-1.04). Adding generation status to the measure of own-region density among migrants resulted in a better fit to the data than overall own-region migrant density, with a 5% decrease in generation-specific migrant density corresponding to an HR of 1.07 (95% CI, 1.04-1.11).
“Although one interpretation of this research might be to suggest that migrants should seek to settle in neighborhoods with a high number of migrants from the same region, this study adds to the growing body of literature that highlights how the broader society may be failing to support the mental health of migrants beyond their communities of support," Dykxhoorn told Healio Psychiatry. "This research emphasizes that we must consider how neighborhoods can support or undermine mental health in migrant groups."
In a related editorial, Deidre M. Anglin, PhD, associate professor in the department of psychology at The City College of New York, noted potential paths for future research, as well as the importance of this study for the field of social epidemiology.
“Future studies should incorporate both objective and subjective indicators of neighborhood ethnic density and context,” Anglin wrote. “Despite not incorporating this subjective perspective of residents, Dykxhoorn and colleagues’ large cohort study represents an important advancement in the field of social epidemiology, bringing us closer to unpacking how the social environment increases risk for psychosis.” – by Joe Gramigna
Disclosures: Dykxhoorn reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures. Anglin reports no relevant financial disclosures.