Cannabis use and use disorders are more common in those with BD and their presence is independently associated with greater disability associated with BD. This exacerbation of BD-related life functioning in those with cannabis abuse/dependence is independent of psychosis and other co-occurring psychopathology and substance use disorders. For individuals presenting with BD, efforts should be made both to assess their extent of cannabis use and, for those presenting with problematic use, to reduce their levels of use. Whether such a reduction has a causal influence on the etiology of BD is speculative but evidence for better treatment outcomes in non-users does exist (Baethge et al., 2005).
