Background and aims
Prior research has found bidirectional associations between psychotic experiences (PEs) and selected substance use disorders. We aimed to extend this research by examining the bidirectional association between PEs and various types of substance use (SU) and substance use disorders (SUDs), and the influence of antecedent mental disorders on these associations.

Design, setting, participants and measurements
We used data from the World Health Organization World Mental Health surveys. A total of 30 902 adult respondents across 18 countries were assessed for (a) six types of life-time PEs, (b) a range of types of SU and DSM-IV SUDs and (c) mental disorders using the Composite International Diagnostic Interview. Discrete-time survival analyses based on retrospective age-at-onset reports examined the bidirectional associations between PEs and SU/SUDs controlling for antecedent mental disorders.

Findings
After adjusting for demographics, comorbid SU/SUDs and antecedent mental disorders, those with prior alcohol use disorders [odds ratio (OR) = 1.6, 95% confidence interval (CI) = 1.2–2.0], extra-medical prescription drug use (OR = 1.5, 95% CI = 1.1–1.9), alcohol use (OR = 1.4, 95% CI = 1.1–1.7) and tobacco use (OR = 1.3, 95% CI = 1.0–1.8) had increased odds of subsequent first onset of PEs. In contrast, those with temporally prior PEs had increased odds of subsequent onset of tobacco use (OR = 1.5, 95% CI = 1.2–1.9), alcohol use (OR = 1.3, 95% CI = 1.1–1.6) or cannabis use (OR = 1.3, 95% CI = 1.0–1.5) as well as of all substance use disorders (ORs ranged between 1.4 and 1.5). There was a dose response relationship between both count and frequency of PEs and increased subsequent odds of selected SU/SUDs.

Conclusions
Associations between psychotic experiences (PEs) and substance use/substance use disorders (SU/SUDs) are often bidirectional, but not all types of SU/SUDs are associated with PEs. These findings suggest that it is important to be aware of the presence of PEs within those with SUDs or at risk of SUDs, given the plausibility that they may each impact upon the other.

Louisa Degenhardt, Sukanta Saha, Carmen C. W. Lim, Sergio Aguilar-Gaxiola, Ali Al-Hamzawi, Jordi Alonso, Laura H. Andrade, Evelyn J. Bromet, Ronny Bruffaerts, José Miguel Caldas-de-Almeida,
Giovanni de Girolamo, Silvia Florescu, Oye Gureje, Josep M. Haro, Elie G. Karam, Georges Karam, Viviane Kovess-Masfety, Sing Lee, Jean-Pierre Lepine, Victor Makanjuola, Maria E. Medina-Mora, Zeina Mneimneh, Fernando Navarro-Mateu, Marina Piazza, José Posada-Villa, Nancy A. Sampson, Kate M. Scott, Juan Carlos Stagnaro, Margreet Ten Have, Kenneth S. Kendler, Ronald C. Kessler, John J. McGrath, on behalf of the WHO World Mental Health Survey Collaborators
Addiction, 21 February 2018
DOI: 10.1111/add.14145
http://onlinelibrary.wiley.com/doi/10.1111/add.14145/abstract

The associations between psychotic experiences and substance use and substance use disorders: findings from the World Health Organization World Mental Health surveys – 2018