Association between tobacco use and symptomatology in individuals at ultra-high risk to develop a psychosis: A longitudinal study

Background: The high prevalence rates and impact of tobacco smoking in individuals with a psychotic disorder have become an increasing interest. Little is known about tobacco smoking in individuals at ultra-high risk of psychosis (UHR). Methods: We studied 345 UHR individuals of the high-risk study of the European network of national schizophrenia networks studying Gene-Environment Interactions (EU-GEI). Smoking status and the number of cigarettes per day were assessed at multiple moments using the CIDI. Symptom severity at each time point was assessed using CAARMS. Linear mixed-effects analyses were conducted to examine the multi-cross-sectional and prospective associations between (change in) smoking behaviour and symptomatology. Findings: At baseline, 175 individuals (53%) smoked tobacco with an average of 12.4 (SD = 9.0) cigarettes per day. Smokers did not significantly differ in symptom severity from non-smokers on general, positive, negative, emotional, cognitive, behavioural, or motor symptoms across time. However, associations were found between the number of cigarettes and the severity of general psychopathology (estimate 0.349, SE 0.146, p = 0.017). Change in the number of cigarettes had no significant effect on change in general symptom severity (estimate 0.330, SE 0.285, p = 0.248). Interpretation: Smoking prevalence in UHR individuals is high. Cigarette consumption was associated with higher levels of general symptoms. However, we observed an association between change in number of cigarettes and symptom severity. Given the fact that smoking is associated with poorer health and worse outcomes in people with psychosis, the clinical high-risk phase offers a window of opportunity for prevention and cessation interventions.