Anxiety and depression and their links with delusions and hallucinations in people with a dual diagnosis of psychosis and substance misuse: a study using data from a randomised controlled trial

Rates of depression and anxiety have been linked to severity and distress associated with positive symptoms in psychosis. There is also tentative evidence to suggest that these concurrent symptoms might be related to delusional and hallucinatory content. Our aim was to assess the cross-sectional associations between anxiety and depression, and hallucination and delusion severity and distress in a sample of 327 people dually diagnosed with psychosis and substance misuse problems. In addition, the relationships between specific symptom content and levels of anxiety and depression were examined. Anxiety was associated with delusion distress and depression with hallucination distress, although neither was related to symptom severity. Auditory commands to harm or kill the self were associated with higher levels of depression. Delusions with themes pertaining to the paranormal, and those with references to celebrities were associated with lower levels of depression. No specific delusion or hallucination content was associated with level of anxiety, when other variables were controlled for. The results demonstrate that anxiety and depression are linked to distinct aspects of psychotic experience, highlighting the need to acknowledge the role of these concurrent symptoms in the context of psychosis. In addition, findings relating to specific types of delusions and hallucinations highlight avenues for further research.