Smoking in different stages of psychosis

The aim of this thesis is to gain more knowledge and understanding about the use of substances (including tobacco smoking, cannabis, and alcohol) in different stages of psychosis. First, we explored whether the negative effects of tobacco smoking previously found in patients with psychotic disorders were already observable in the at-risk phase of psychosis. Therefore, we investigated the associations between cigarette smoking, symptomatology, and cognitive functioning in patients with an ultra-high risk (UHR) for psychosis. Alarmingly, we found that one in every two UHR individuals reported daily use of tobacco and that the severity of smoking was associated with mainly affective symptoms. Furthermore, we investigated whether psychological mechanisms could (partially) explain the extremely high smoking prevalence found in patients with different vulnerabilities for psychosis. We observed that maladaptive coping and the experience of trauma were related to the risk of smoking. Lastly, we evaluated the social associations of substance use in patients with more established forms of a psychotic disorder. Contrary to our expectations, we observed that substance use, including alcohol and cannabis, was related to better scores on different aspects of social functioning. In conclusion, high rates of smoking are already observed in the at-risk phase of psychosis. Also, the negative effects of smoking on mental health may already be visible. For some patients, it might be that substance use is considered helpful to engage in social contact. To help patients in decreasing substance use, it is essential to be aware of the psychological reasons for substance use and to refer the patient to psychological and behavioural treatment if needed.