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28 June 2021

'Not fitting in' with the local neighbourhood does not increase risk of severe mental illness

Growing up in a socio-economically disadvantaged home increases risk of severe mental illness to the same extent whether or not the neighbourhood is disadvantaged.

Diverse teenagers

Historically, studies have suggested that the kind of social environment in which people live can influence whether they go on to develop a severe mental illness, such as schizophrenia.

This is important because for many years it was argued that these disorders were purely biological in origin. Yet relatively little is known about the specific social factors that are relevant.

New research published in Psychological Medicine and led by Dr Peter Schofield, Senior Lecturer in Population Health at Kings, indicates that it is not simply a lack of fit due to growing up at a disadvantage that is relevant.

We set out to see whether not fitting in due to a range of different types of disadvantage in childhood would also be associated with a greater risk of subsequent severe mental illness. For example, would growing up in a low-income family be a greater risk factor if you lived in an area where this was unusual, compared to growing up in an area where a low-income background was usual?

Dr Peter Schofield

Using data for the entire population of Denmark collected over a thirty-year period, the researchers looked at disadvantage based on parents’ circumstances at age 15, including: being on a low income, having a manual occupation, being unemployed or having a single parent.

They found no evidence that a lack of fit because of these types of disadvantage was a risk factor for severe mental illness - in contrast to previous studies, including their own, which looked at ethnic density.

This earlier research produced evidence suggesting that the extent to which people are isolated from others from the same ethnic group may be a factor – so that, for example, black people living in more white areas are at greater risk. This is termed the “ethnic density” effect.

The latest study into lack of social fit is important as relatively little is known about the kind of social factors that contribute to severe mental illness. Additionally, while evidence for an ethnic density effect has been consistently shown, little is known about why this occurs.

This study shows that it is not simply a lack of fit due to growing up at a disadvantage that is relevant. Rather, it seems that there is something more specific about being isolated as a result of one’s ethnic group that is important.

To explore the relation between group density and psychosis in more depth the researchers are currently working on a comparative study looking at these questions as they apply to refugees - the migrant group who appear to be at most risk of severe mental disorders.

Read the full paper: Lack of fit with the neighbourhood social environment as a risk factor for psychosis – a national cohort study