The relationship between cannabis involvement and STB could be explained in multiple ways. For example, the self-medication hypothesis states that individuals use psychoactive substances to reduce negative affective states, such as STB (Khantzian, 1985, 1997). However, longitudinal studies have found little support for this hypothesis (Harris and Barraclough, 1997; Van Ours et al., 2013). Alternatively, the impaired functioning theory hypothesizes that cannabis involvement causes STB (Newcomb et al., 1999). Physical, psychological, or emotional functioning is impaired by the repeated and, often, early onset, use of cannabis, resulting in a higher risk of suicidal behaviors. Some longitudinal studies indeed showed a significant relationship between early cannabis use and later risk of suicidal behaviors (e.g., Lynskey et al., 2004; Van Ours et al., 2013; Wilcox and Anthony, 2004). In the present study, while we did not have data on age at first CUD symptom, median age at first cannabis use coincided with the median age at first SI (18 years) in cannabis users and only preceded first suicide attempt by a year. Hence, cannabis involvement likely occurred contemporaneously. Finally, as stated by
