Association Between Population Density and Genetic Risk for Schizophrenia

Area of Science:

• Psychiatry
• Genetics
• Urban Health

Background:

• Urban environments are linked to increased schizophrenia prevalence.
• An alternative hypothesis suggests individuals with higher genetic risk may self-select into urban settings.

Purpose of the Study:

• To investigate if adults with elevated genetic risk for schizophrenia are more likely to live in populated areas.
• To assess the association between polygenic risk scores for schizophrenia and residential population density.

Main Methods:

• Analysis of four large, cross-sectional cohorts (QIMR, UKB, NTR, QSKIN) of genotyped adults of European ancestry.
• Utilized postcode data to determine population density and genome-wide association analysis to derive polygenic risk scores for schizophrenia.
• Employed Mendelian randomization (MR) to explore potential causal associations.

Main Results:

• A significant positive correlation was found between higher genetic risk for schizophrenia and living in more densely populated areas across all cohorts.
• This genetic association explained a small but significant proportion of schizophrenia risk (1.7%).
• MR analyses suggested a potential causal link between genetic liability to schizophrenia and urban living.

Conclusions:

• The study findings support the hypothesis that individuals with higher genetic schizophrenia risk tend to reside in urban/dense areas.
• Results indicate a need to refine schizophrenia models to include genetic factors and potential gene-environment interactions.