Relationships between psychotic and affective symptoms, schizotypal and dissociative phenomena, and adverse life events among individuals with psychotic disorders

Background: Psychotic symptoms and self-rated schizotypal phenomena have similar dimensional structures. Additionally, dissociative phenomena have conceptual links with psychosis/schizotypy and all of these phenotypes are associated with adverse life events (ALEs). The relationships between these factors among individuals with psychotic disorders are not well established and were investigated in this study.

Method: 76 participants with any psychotic disorder were recruited from mental health services in West Yorkshire, UK. Lifetime psychotic and affective symptoms were assessed by research interviews and case record review. The self-rated Schizotypal Personality Questionnaire (SPQ) with additional questions regarding inappropriate affect, Dissociative Experiences Scale (DES), and questionnaires regarding cumulative adverse life events in childhood (CLEQ) and in the year before clinical onset (BLEQ) were also administered. Relationships between factors were assessed using Spearman correlations and linear regression analysis.

Results: Correlations with relevant psychotic symptoms ranged from ~0.3 for some positive and negative SPQ subdomains to ~0 for disorganised subdomains. In contrast, SPQ and DES were highly correlated (~0.7). In univariate analysis, ALEs were associated with depression, DES, and positive and disorganised SPQ subdomains. In multivariable analysis, ALEs in childhood and before onset were independently associated with the SPQ Unusual perceptual experiences subdomain.

Conclusion: Among individuals with psychotic disorders, neither SPQ nor DES questionnaire responses are likely to be useful proxies for psychotic symptoms. However, particularly questionnaire-based unusual perceptual experiences may be useful when assessing the range of phenomena associated with adverse life events.