How does loneliness interact with positive, negative and depressive symptoms of psychosis? New insights from a longitudinal therapy process study.

Cross-sectional research suggests an association between loneliness and psychotic symptoms, but the causal direction of this association is still unclear. Even though loneliness has been proposed as a potential treatment target to improve psychotherapy for psychosis, not much is known about its role in the treatment process. In this study, we re-analyzed data from a therapy process study to investigate the temporal dynamics between loneliness and psychotic symptoms throughout therapy and to explore whether state-of-the-art CBT for psychosis (CBTp) decreases loneliness. Over the course of up to 45 weekly sessions of CBTp, 57 patients reported their feelings of loneliness and current positive, negative and depressive symptom levels at each session. Multilevel regression revealed a reduction in all symptoms over time, but no reduction in loneliness. Time-lagged multilevel regression showed that loneliness predicted subsequent negative and depressive symptoms, whereas positive symptom levels predicted subsequent loneliness. Thus, changes in loneliness seem to be both cause and consequence of psychotic symptom changes. These findings highlight the importance of loneliness as a treatment target, particularly in patients with negative symptoms and depression. Future research should address loneliness-specific interventions as an augmentation of state-of-the-art CBTp.