I considered Arseneault et al's (Reference Arseneault, Cannon and Wittan2004) search for evidence of the association between cannabis and psychosis as quite skewed. They did not explore the evidence regarding positive, therapeutic or beneficial psychoactive effects of cannabis in mental health in the context of appropriate, rational and clinical usage.
It is now known that the major psychoactive constituent of cannabis and endogenous cannabinoid ligands signal through G-protein-coupled cannabinoid receptors localised to regions of the brain associated with important neurological processes (Reference IversenIversen, 2003). Signalling, mostly inhibitory, suggests a role for cannabinoids as therapeutic agents in central nervous system disease where inhibition of neurotransmitter release would be beneficial. Evidence suggests that cannabinoids inhibit the neurotransmitter glutamate, counteract oxidative damage to dopaminergic neurons and may be potent neuroprotective agents (Reference CroxfordCroxford, 2003). These findings open the door to exploration of the physiological role of the anandamide system, and its involvement with mood, memory and cognition, perception, movement, coordination, sleep, thermoregulation, appetite, and immune response. Cannabis users have reported effectiveness of cannabis in relieving aches and pains, fatigue and tiredness, numbing the symptoms of opiate withdrawal, improving sleep, reducing anxiety, and alleviating the vomiting, anorexia, and depression associated with AIDSrelated disorders (Reference RobsonRobson, 1998). The anxiolytic, hypnotic, appetite-stimulating and antidepressant properties are a compelling reason for research into the use of cannabinoids in psychiatric therapeutics; controlled clinical trials are needed. The role of cannabinoids in modern therapeutics remains uncertain, but there is evidence that it would be irrational not to explore it (Reference RobsonRobson, 1998) and, knowing its potent neuroprotective function, its potential role in psychiatric practice should not be discarded lightly.