Summary: A study found that the neighborhood where a person lived at age fifteen strongly influenced their risk of developing both affective psychosis (such as bipolar disorder) and non-affective psychosis (such as schizophrenia) later in life.
Source: King’s College London
This first-of-its-kind study, published in Schizophrenia Research, examined whether demographic and neighbourhood factors have different impacts on the later development of non-affective psychosis (for example, schizophrenia) compared with affective psychosis (for example, bipolar disorder).
Prior research has shown that rates of some severe mental illnesses, notably non-affective psychoses such as schizophrenia, vary by geographical location. In contrast, affective psychoses like bipolar disorder have not consistently shown the same geographical variation, despite sharing many clinical and social features with non-affective conditions.
Building on earlier work by Dr. Peter Schofield investigating how neighbourhood context relates to severe mental illness, the authors of this study used comprehensive national registry data from Denmark to investigate neighbourhood influences across the whole population.
The analysis focused specifically on the neighbourhood in which individuals lived at age 15 and tracked their subsequent medical records to determine the likelihood of developing non-affective psychosis (such as schizophrenia) or affective psychosis (such as bipolar disorder) later in life.
The study found that neighbourhood of residence at age 15 was a significant factor associated with later rates of both non-affective and affective psychoses. In particular, neighbourhood ethnic density—defined by the proportion of residents from the same ethnic group—was associated with rates of both types of psychosis among people from ethnic minority backgrounds.
However, the patterns differed when examining urbanicity. The study found a clear association between higher urbanicity and increased rates of non-affective psychosis, but no comparable relationship with affective psychosis. Individuals who lived in the most urban neighbourhoods at age 15 experienced a substantially higher rate of later non-affective psychosis compared with those from the least urban areas, while affective psychosis rates showed minimal difference across urban-rural gradients.
These findings suggest that while some neighbourhood-level influences—such as ethnic density—may affect both affective and non-affective psychoses similarly, other environmental factors like urbanicity may contribute specifically to the development of non-affective psychoses. The authors highlight that this divergence could reflect distinct underlying pathways leading to these different categories of psychotic disorders, and they recommend further research to clarify the mechanisms involved.
About this psychosis research news
Author: Press Office
Source: King’s College London
Contact: Press Office – King’s College London
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Original Research: Open access.
“A comparison of neighbourhood level variation and risk factors for affective versus non-affective psychosis” by Peter Schofield et al. Schizophrenia Research
Abstract
A comparison of neighbourhood level variation and risk factors for affective versus non-affective psychosis
Background
Previous studies generally report area-level differences in the incidence of non-affective psychoses but not affective psychoses. In this study, the authors directly compared neighbourhood-level variation for both categories of disorder and investigated how neighbourhood urbanicity and ethnic density influenced risk, using Danish national registry data.
Methods
The research used a population-based cohort of 2,224,464 individuals followed from 1980 to 2013. Neighbourhood exposure was defined at age 15, and incidence of psychotic disorders was modelled using multilevel Poisson regression to estimate neighbourhood-level effects alongside individual-level risk factors.
Results
Neighbourhood variation was similar for both types of disorder: the adjusted median risk ratio was 1.37 (95% CI 1.34–1.39) for non-affective psychosis and 1.43 (1.38–1.49) for affective psychosis. Associations with neighbourhood urbanicity differed markedly. Living in the most urban quintile at age 15, compared with the least urban quintile, was associated with only a small increase in subsequent affective psychosis, IRR 1.13 (1.01–1.27), but a substantial increase in non-affective psychosis, IRR 1.66 (1.57–1.75). Findings for neighbourhood ethnic density varied by migrant group: for Middle Eastern migrants, each decrease in ethnic density quintile was associated with higher average incidence of both affective psychosis, IRR 1.54 (1.19–1.99), and non-affective psychosis, IRR 1.13 (1.04–1.23); a similar pattern was observed for African migrants. For European migrants, lower ethnic density appeared to be associated with non-affective psychosis only.
Conclusions
Overall neighbourhood-level variation and the effect of ethnic density were similar for affective and non-affective psychoses, but associations with urbanicity were largely confined to non-affective psychosis. These differences may point to distinct aetiological pathways for the two disorder types, though the precise mechanisms remain unknown. The findings underscore the importance of considering specific neighbourhood factors—such as urban environment and ethnic composition—when studying risk and prevention strategies for psychotic disorders.