Brain Sciences


Psychotic symptoms in teenage years linked to being born in city

26 June 2019

Being born in more densely-populated areas, or neighbourhoods with greater social fragmentation, is linked to a greater risk of developing psychotic symptoms in adolescence, independent of genetic risk for schizophrenia, finds a new UCL study.

Chicago city

The study, published in Schizophrenia Bulletin, finds people born in the most densely-populated third of the sample were 1.57 times more likely to have positive psychotic symptoms such as hallucinations or delusions by age 16-18. Importantly, the research found that genetic predisposition to schizophrenia did not account for these associations, leading to further evidence that a more stressful and chaotic urban environments could be the cause.  

Senior author Dr James Kirkbride (UCL Psychiatry) said: “Although psychotic symptoms are rare, our findings suggest that being born into certain environments which may sometimes be more stressful – including more urban, or socially fragmented neighbourhoods – can affect adolescents’ risk of psychotic-related symptoms.

“If causal, this suggests that helping young people navigate stressful environments may also benefit their mental health.”

The variables used in the study were population density, social fragmentation, inequality and deprivation at birth, all measured from the 1991 census at small area level and linked to participants’ address at birth.

“We found that population density predicted more psychotic symptoms in adolescence, and that social fragmentation - when areas have more social problems, like social isolation and turnover of population - predicted more negative symptoms (things that might index social withdrawal, which is a common symptom of psychotic disorder).

“Importantly, we found that while children with a higher genetic risk for schizophrenia were born into more deprived neighbourhoods, genetic liability to schizophrenia did not predict birth into more densely populated or socially fragmented neighbourhoods, raising the possibility that factors in such environments may contribute to greater psychosis risk in adolescence,” said Dr Kirkbride.

He said more work needs to be done to understand how living in a more urban environment might increase risk of psychotic symptoms such as delusions and hallucinations, and to understand whether these factors go on to predict clinical levels of disorder in this cohort.