The Impact of Marijuana on Mental Health

Abstract

The association between marijuana use and several mental health outcomes is examined, with particular reference to commonly held views on the lack of proof for a causal basis. Rather than relying on a single, key criterion for proof of causation, a collective approach is taken to the question through reviewing studies testing different criteria. Exploration of the psychiatric epidemiology on marijuana reveals trends in early reports that have been confirmed through more detailed studies in recent years and further bolstered by clinical findings. A significant, causal role for marijuana use in chronic psychotic disorders is substantiated by the literature, as well as a strong association with mood disorders and suicidal behaviors. This chapter reinforces the importance of considering marijuana’s mental health impacts when formulating appropriate public health programs and when fashioning drug control policies concerning its legal status.