Psychosis rates can be nearly eight times higher in some regions compared to others, finds a new study led by researchers at the University of California (US), King’s College London and the University of Cambridge (UK). ).
The study, published in the journal JAMA Psychiatry , represents the largest international comparison of the incidence of psychotic disorders, and the first large study of its kind in more than 25 years.
“It is well established that psychotic disorders, such as schizophrenia, are highly heritable, but genetics does not tell the whole story. Our findings suggest that environmental factors may also play a role ,” explains James Kirkbride, leader of the work.
“We need more in-depth research to understand why people in some areas may be at higher risk of developing a psychotic disorder, which could help us understand the roots of the disease and guide health care planning, ” he continues.
The authors calculated the incidence of psychotic disorders in 17 areas in six countries: the United Kingdom, France, Italy, the Netherlands, Spain and Brazil, using a comparative methodology with data from people between 18 and 64 years of age who contacted the mental health services after a suspected first psychotic episode, which included 2,774 cases in total.
They found that the overall incidence of psychotic disorders was 21.4 per 100,000 people per year, but found wide variations between different areas, from a low of 6.0 per 100,000 people per year in the rural area around Santiago, Spain, to a high from +45 in Paris city center and South East London. This variation cannot be explained by differences in the age, sex, and ethnic composition of the population in these areas.
Among the factors contributing to this increase in psychotic disorders, the strongest predictor was a low rate of owner-occupied homes. The researchers used owner-occupied housing as an indicator of prosperity and socioeconomic stability, showing that this incidence could be related to precariousness.
“Areas with higher rates of owner-occupied housing have lower rates of psychosis. People in socially deprived areas may have more social stress, which could predict the incidence of psychosis, as other studies suggest. An alternative explanation could be that owner-occupied housing is an indicator of social stability and cohesion, in relation to stronger support networks “, clarifies Hannah Jongsma, co-author of the work.
According to previous research, a higher incidence of psychosis was also associated with younger people, men and ethnic minorities.
Experts say their findings can be used to help plan mental health services by identifying which regions could expect a higher incidence of psychosis. Some of the researchers have developed a predictive model that health agencies are already putting into practice.
“We can predict, with increasing precision, what the incidence rates are in a given region, based on readily available demographic data. This can help plan where to focus resources for the treatment and prevention of psychotic disorders. “says Jim van Os, a co-author of the study.
The findings add weight to previous evidence that environmental factors may play a much larger role than previously believed in the development of psychotic disorders.
Referencia: Treated Incidence of Psychotic Disorders in the Multinational EU-GEI Study. JAMA Psychiatry. Published online December 6, 2017. doi:10.1001/jamapsychiatry.2017.3554
