Evidence That Environmental and Familial Risks for Psychosis Additively Impact a Multidimensional Subthreshold Psychosis Syndrome

Abstract

Background: The observed link between positive psychotic experiences (PE) and psychosis spectrum disorder (PSD) may be stronger depending on concomitant presence of PE with other dimensions of psychopathology. We examined whether the effect of common risk factors for PSD on PE is additive and whether the impact of risk factors on the occurrence of PE depends on the co-occurrence of other symptom dimensions (affective dysregulation, negative symptoms, and cognitive alteration).

Method: Data from the Netherlands Mental Health Survey and Incidence Study 2 were used. Risk factors included childhood adversity, cannabis use, urbanicity, foreign born, hearing impairment, and family history of affective disorders. Logistic regression models were applied to test (1) the additive effect of risk factors (4 levels) on PE and (2) the moderating effects of symptom dimensions on the association between risk factors (present/absent) and PE, using additive interaction, expressed as the interaction contrast ratio.

Results: Risk factors were additive: the greater the number of risk factors, the greater the odds of PE. Furthermore, concomitant presence of the other symptom dimensions all increased the impact of risk factors on PE. After controlling for age, sex, and education, only affective dysregulation and negative symptoms remained significant moderators; only affective dysregulation remained a significant moderator if all dimensions were adjusted for each other.

Conclusions: Risk factors may not be directly associated with PE but additively give rise to a multidimensional subthreshold state anticipating the multidimensional clinical syndrome. Early motivational and cognitive impairments in the context of PE may be reducible to affective dysregulation.

Fig. 1.

The frequencies of risk factors within risk factor strata at baseline assessment. This figure shows the frequencies of individual risk factors in each risk stratum at baseline: No risk factor = 0, low risk = 1 risk factor, medium risk = 2 risk factors, and high risk > 2 risk factors. Data were given in percentages based on the individual sample sizes of the low, medium, and high risk groups, respectively.

Fig. 2.

The prevalence of psychotic experience across risk strata. This figure reports the percentage of people with at least one PE within each risk stratum: No risk factors = 0, low risk = 1 risk factor, medium risk = 2 risk factors, and high risk > 2 risk factors.

Fig. 3.

Figure shows the additive effects of symptom dimensions (A: affective dysregulation, B: negative symptoms, C: cognitive alteration) on the association between risk factors and PE adjusted for sex, age, and education.