Influence of perceived harm due to substance use on the relationships between positive psychotic experiences and suicidal experiences in people with non-affective psychosis

Abstract

Background: The ways in which perceived harm due to substance use affects relationships between psychotic and suicidal experiences are poorly understood. The goal of the current study was to redress this gap by investigating the moderating effects of harm due to substance use on pathways involving positive psychotic symptoms, the perceived cognitive-emotional sequelae of those symptoms, and suicidal ideation.

Method: The design was cross-sectional. Mediation and moderated mediation pathways were tested. The predictor was severity of positive psychotic symptoms. Cognitive interpretative and emotional characteristics of both auditory hallucinations and delusions were mediators. Suicidal ideation was the outcome variable. General symptoms associated with severe mental health problems were statistically controlled for.

Results: There was evidence of an indirect pathway between positive psychotic symptom severity and suicidal ideation via cognitive interpretation and emotional characteristics of both auditory hallucinations and delusions. Harm due to drug use, but not alcohol use, moderated the indirect pathway involving delusions such that it was most prominent when harm due to drug use was at medium-to-high levels. The components of suicidal ideation that were most strongly affected by this moderated indirect pathway were active intent, passive desire, and lack of deterrents.

Conclusions: From both scientific and therapy development perspectives, it is important to understand the complex interplay between, not only the presence of auditory hallucinations and delusions, but the ensuing cognitive and emotional consequences of those experiences which, when combined with harm associated with substance use, in particular drug use, can escalate suicidal thoughts and acts.

Keywords: active suicidal thoughts; alcohol use; auditory hallucinations; delusions; drug use; passive suicidal thoughts; psychosis; schizophrenia; substance use; suicide.

Figure 1.

Postulated moderated mediated pathway from the presence of positive psychotic symptoms to suicidal ideation via two mediators of cognitive interpretation and emotional characteristics of delusions and auditory hallucinations. The moderator is perceived harm due to substance use. The predicted mediated pathways are shown as solid lines.

Figure 2.

Significant mediation pathways from positive psychotic symptoms to suicidal ideation via two sequential mediators of cognitive interpretation characteristics and emotional characteristics of delusions (N = 201) and auditory hallucinations (N = 193) with general psychiatric symptoms as a control variable. This was the only significant indirect effect (a × b1 × b2) for both delusions (effect = 0.27, s.e. = 0.11, CI = 0.04–0.49) and hallucinations (effect = 0.06, s.e. = 0.04, CI = 0.006–0.12). The direct effect (path c′) from positive psychotic symptoms to suicidal ideation was not significant for delusions (effect = 0.06, s.e. = 0.17, CI = −0.28 to 0.40) nor for hallucinations (effect = 0.04, s.e. = 0.14, CI = −0.24 to 0.31).

Figure 3.

Moderating effect of perceived harm due to drug use on the strength of the relationship between the severity of cognitive interpretation characteristics of delusions and suicidal ideation. This relationship was strongest when harm due to drug use was high (1 s.d. above the mean) and weakest when harm due to drug use was low (1 s.d. below the mean). The same pattern of findings occurred for the relationship between the severity of emotional characteristics of delusions and suicidal ideation.