Association of neighbourhood migrant density and risk of non-affective psychosis: a national, longitudinal cohort study

Abstract

Background Elevated risk of psychotic disorders in migrant groups is a public mental health priority. We investigated whether living in areas of high own-region migrant density was associated with reduced risk of psychotic disorders among migrants and their children, and whether generation status, probable visible minority status, or region-oforigin affected this relationship. MethodsWe used the Swedish registers to identify migrants and their children born between Jan 1, 1982, and Dec 31, 1996, and living in Sweden on or after their 15th birthday. We tracked all included participants from age 15 years or date of migration until emigration, death, or study end (Dec 31, 2016). The outcome was an ICD-10 diagnosis of non-affective psychosis (F20-29). We calculated own-region and generation-specific own-region density within the 9208 small areas for market statistics neighbourhoods in Sweden, and estimated the relationship between density and diagnosis of non-affective psychotic disorders using multilevel Cox proportional hazards models, adjusting for individual confounders (generation status, age, sex, calendar year, lone dwelling, and time since migration [migrants only]), family confounders (family income, family unemployment, and social welfare), and neighbourhood confounders (deprivation index, population density, and proportion of lone dwellings), and using the Akaike information criterion (AIC) to compare model fit. Findings Of 468 223 individuals included in the final cohort, 4582 (1•0%) had non-affective psychotic disorder. Lower own-region migrant density was associated with increased risk of psychotic disorders among migrants (hazard ratio[HR] 1•05, 95% CI 1•02-1•07 per 5% decrease) and children of migrants (1•03, 1•01-1•06), after adjustment. These effects were stronger for probable visible minority migrants (1•07, 1•04-1•11), including migrants from Asia (1•42, 1•15-1•76) and sub-Saharan Africa (1•28, 1•15-1•44), but not migrants from probable non-visible minority backgrounds (0•99, 0•94-1•04). Among migrants, adding generation status to the measure of own-region density provided a better fit to the data than overall own-region migrant density (AIC 36 103 vs 36 106, respectively), with a 5% decrease in generation-specific migrant density corresponding to a HR of 1•07 (1•04-1•11).Interpretation Migrant density was associated with non-affective psychosis risk in migrants and their children. Stronger protective effects of migrant density were found for probable visible minority migrants and migrants from Asia and sub-Saharan Africa. For migrants, this risk intersected with generation status. Together, these results suggest that this health inequality is socially constructed.

A comprehensive systematic review and multilevel meta-analysis of the ethnic density effect in psychosis

“…Fourteen studies were conducted (45%) in the UK 9,11,[25][26][27][28][29][30][31][32][33][34][35][36] , eight (26%) in the Netherlands [37][38][39][40][41][42][43][44] , and four (13%) in Sweden [45][46][47][48] . Of the remaining five (16%), two were conducted in Denmark 49,50 , and one of each in the USA 51 , Canada 52 , and Australia 53 .…”

“…The majority were retrospective epidemiological studies (n=26, 84%) 9,11,[25][26][27][28][29][30][31][32][33][34][35][36][39][40][41][42][45][46][47][48][49][50]52,53 . Of these, most were cross-sectional and six (four datasets) used longitudinal methods 32,[46][47][48][49][50] . All of these studies were conducted in a neighbourhood context with the exception of one which considered a school setting 46 .…”

“…Around half of the studies (n=15, 48%) examined first incident cases 9,[25][26][27]31,35,36,39,41,42,[45][46][47]49,50 and six (19%) used measures of subclinical psychosis 11,[28][29][30]33,51 . The others assessed symptomatic outcomes 37,38,43,44 , mortality rates 32 , inpatient days following admission 34 , compulsory admission 48 , individuals meeting ultra-high risk [UHR] criteria 53 , dispensed antipsychotic medication 40 , lifetime prevalence of psychosis 52 , psychophysiological outcomes 43 , and social distance 43,44 .…”

“…Seventeen studies (fifteen datasets) reported associations for aggregated black and minority ethnic or migrant groups 9,11,26,29,[32][33][34][35][36]39,42,[45][46][47][48]52,53 . In combined minority groups in the UK 9,11,26,29,33,35,36 and migrant groups in Sweden [45][46][47] , the Netherlands 39,42 , and Canada 52 , all but one study 45 found associations in the expected direction for clinical 9,26,35,36,39,42,46,47 and non-clinical outcomes 11,29,33 , with most finding significant interactions 9,11,26,33,39,42,46,47 . Between-group density effects tended to be stronger than withingroup effects <...>…”

Objective and subjective neighbourhood characteristics and suicidality: a multilevel analysis

“…SAMS use administrative boundaries to delineate socioeconomically homogenous areas containing between 1,000 and 2,000 individuals. 17 We merged any SAMS area with less than 50 inhabitants with the adjacent SAMS, 18 resulting in 889 neighbourhood areas in our cohort. Those individuals did not have a valid address at baseline and thus could not be assigned a neighbourhood were excluded (n=18).…”