More threads by David Baxter PhD

David Baxter PhD

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Environmental factors combine with developmental expression of psychosis02
02 April 2007
Psychol Med 2007; 37: 513?527

Environmental risk factors act together to increase the risk of psychosis, say European researchers.

They also found that psychotic experiences additively affect the continuous developmental environmental load leading to persistent psychosis and the need for care.

Previous studies have indicated that low-grade psychotic experiences are common in the general population, but represent a transitory developmental phenomenon, explains Jim van Os, from Maastricht University in The Netherlands, and colleagues.

The researchers investigated whether common, non-clinical development expression of psychosis may become abnormally persistent when combined with developmental exposures, such as cannabis, trauma, and urbanicity.

They studied data on 7076 individuals from the Netherlands Mental Health Survey and Incidence Study (NEMESIS) and 3021 participants in the Early Developmental Stages of the Psychopathology (EDSP) study, based in Germany.

The researchers calculate that the persistence rates for psychotic experiences at 3 years were low in the two studies, at 26% in NEMESIS and 31% in the EDSP study.

Nevertheless, the persistence rates progressively increased with greater numbers of environmental exposures at baseline in both studies.

The synergistic activity of environmental exposures and psychotic experience at baseline meant that 21?83% of NEMESIS patients and 29?51% EDSP patients who were exposed to at least two environmental factors and had experienced psychosis at baseline had persistent psychotic experiences at follow-up.

The team writes in the journal Psychological Medicine: "Cumulative exposure to these additively acting developmental environmental risk factors in subjects with liability for psychosis, as evidenced by psychotic experiences, may result in cumulative changes in the functioning of the dopamine system, possibly affecting the persistence and deterioration of developmental psychotic features."

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