Symptom networks of psychotic experiences and functional somatic symptoms in adolescence: A cross-sectional study of two population-based cohorts

Background: Contemporary theoretical models underlying development of psychotic- and functional disorders show similarities, including attribution of aberrant salience to everyday (bodily) sensations and an increased tendency of top-down generation of perception. In two general population samples of adolescents, we aimed to examine potential associations between subclinical phenomena, namely functional somatic symptoms (FSS) and psychotic experiences (PE). Methods: We used data from two cohorts of adolescents aged 15–17 years: the Copenhagen Child Cohort 2000 (Denmark, n = 2550) and the TRacking Adolescents' Individual Lives Survey (the Netherlands, n = 1665). We identified comparable self-reported symptoms of FSS and PE respectively in each cohort. The cohort data were analyzed separately to enable replication, and mixed graphical models were used to estimate symptom networks. First, networks including only FSS and PE were modelled. Second, an emotional symptom score was included in the networks. Results: While numerous specific symptom-to-symptom cross-domain associations were not replicated, symptom networks of the two cohorts overall showed relatively comparable patterns. Delusions of persecution showed the strongest connection with FSS in both cohorts. In the models including emotional symptoms, emotional problems were associated with many PE and FSS, but did not fundamentally change the structure of the original networks. Conclusion: Using a symptom-based approach the current study lent little support to the notion of specific associations between PE and FSS, yet associations between FSS and PE in adolescence were found in both cohorts. The associations between the two domains could not be fully explained by shared associations with emotional problems.