Cannabis and mental health

Cannabis contains a variety of psychoactive compounds, in particular tetrahydrocannabinol. There are cannabinoid receptors throughout the brain and in other tissues, and use of cannabis produces a range of psychological and physiological effects. People who enjoy the effect of cannabis report a pleasant detachment from their surroundings and an alteration in their perception of events, which lasts for several hours after smoking or eating cannabis. A proportion of users report transient anxiety symptoms and increased suspiciousness and lethargy. Physiological effects include tachycardia, increased appetite, dry mouth and red eyes. Regular cannabis use can be associated with tolerance to the effects of the drug and withdrawal symptoms, including irritability, insomnia and cravings for the drug.