Evidence of mediation of severity of anxiety and depressive symptoms between abuse and positive symptoms of psychosis

Abstract

Background: Considerable evidence on general population suggests that an "Affective pathway to psychosis", involving depression and anxiety dimensions, mediates the abuse-psychosis association. However, this has never been tested in Early Psychosis (EP) patients. We aim at testing whether severity of depressive and anxiety mediates the abuse-positive symptoms dyad in an EP prospective sample.

Methods: 330 EP subjects aged 18-35 were assessed for psychopathology after 2, 6, 12, 18, 24, 30, and 36 months of treatment. Abuse was considered as facing at least one experience of physical, sexual, or emotional abuse before age 16. Positive psychotic symptoms and anxiety were measured with the Positive and Negative Syndrome Scale and depressive symptoms with the Montgomery-Asberg Depression Rating Scale. Mediation analyses were performed to study whether the abuse-positive symptom's link was mediated by depressive, anxiety, and a combination of anxiety/mood symptoms.

Results: Among the 330 EP patient included, 104 (31.5% of the total) were exposed to abuse. Analyses across the 36 months of follow-up showed that depression and anxiety partially mediated 26.7% of the total effect of the abuse-positive symptoms association (indirect effects (IE) = 0.392 and 0.421 respectively), while the combined anxiety/mood model mediated 28.9% (IE = 0.475). Subanalyses at two and 36 months revealed a consistent role of depression, while that of anxiety was only present at baseline.

Conclusion: Our work confirms a mediating role of mood and anxiety in the association between abuse and positive symptoms during the first three years of treatment.

Keywords: Early psychosis; Mediation; Positive symptoms; Trauma.