Living in a city has been identified as a potential risk factor for schizophrenia and, to a lesser extent, other mental illnesses. However, few research have looked into the impact of genetics on where people choose to live.
New research published in JAMA Psychiatry refutes the notions that city life is merely an environmental risk factor for schizophrenia or that people with mental illnesses relocate to cities in quest of better healthcare.
Instead, the findings show that a person’s genetic susceptibility to a variety of mental health issues may influence where they live. The Maudsley Biomedical Research Center of the National Institute for Health Research (NIHR) contributed to the research.
First author Jessye Maxwell, Ph.D. candidate from Institute of Psychiatry, Psychology & Neuroscience (IoPPN), King’s College London, said: “Our research shows that at some level an individual’s genes select their environment and that the relationship between environmental and genetic influences on mental health is interrelated. This overlap needs to be considered when developing models to predict the risk of people developing mental health conditions in the future.”
“Importantly the majority of those people in our analysis did not have a diagnosed mental health condition so we are showing that across the UK adult population this genetic risk for mental health conditions plays a role in the environment that people live.”
The researchers estimated the polygenic risk score (PRS) for each individual for different mental health disorders using genetic data from 385,793 UK Biobank participants aged 37 to 73. Rather than analyzing liability at the level of individual genes, the PRS examines genetic liability throughout an individual’s entire genome.
Our study provides further evidence that genetic liability to a variety of mental disorders may contribute to the choice of a person’s environment. The findings do not negate the important role that environment plays in the development of mental health conditions but it does suggest that we need more integrated approaches when exploring the causes of psychiatric disorders.
Dr. Evangelos Vassos
Address history and the geographical distribution of population density in the UK based on census data from 1931 to 2011 were used to examine the relationship between where individuals presently live and where they have migrated to.
In comparison to those who stayed in rural regions, those who relocated to urban areas had increased genetic risks of schizophrenia, bipolar disorder, anorexia, and autistic spectrum disorder, as well as decreased genetic risks of ADHD.
Lead author, Dr. Evangelos Vassos, Research Fellow at the IoPPN, King’s College London and Consultant Psychiatrist said: “Our study provides further evidence that genetic liability to a variety of mental disorders may contribute to the choice of a person’s environment. The findings do not negate the important role that environment plays in the development of mental health conditions but it does suggest that we need more integrated approaches when exploring the causes of psychiatric disorders.”
The findings on ADHD are particularly intriguing since, unlike other mental illnesses, those with a low genetic risk of getting ADHD to appear to prefer to live in cities. This finding emphasizes the necessity of looking at those at the low end of the genetic liability spectrum rather than just those at high risk. More research is needed to fully comprehend the reasons for this divergence.
Researchers from King’s College London’s Institute of Psychiatry, Psychology & Neuroscience’s Social, Genetic and Developmental Psychiatry Centre conducted the study.
The Great Britain Historical GIS Project, Humphrey Southall, and the University of Portsmouth provided census data through www.VisionofBritain.org.uk, which uses statistical content that is copyrighted by the Great Britain Historical GIS Project, Humphrey Southall, and the University of Portsmouth.
