Mental health articles

Cannabis

Although not generally available for therapeutic use research into the various potential medicinal benefits of tetrahydrocannabinols – THC (the psychoactive ingredient in cannabis) is in progress. Cannabis can come as a green/brown block of compressed resin (‘hash’, ‘blow’, ‘draw’) or as herbal cannabis, the leaves, stalks and seeds of the plant (‘marijuana’, ‘grass’, ‘weed’). ‘Skunk’ is a particularly strong variety. Cannabis is usually smoked with tobacco in a ‘joint’ or ‘spliff’, but can be smoked in a pipe. It can also be eaten. Cannabis is the most commonly used illicit drug in the UK. The effects of cannabis depend to a large extent on the expectations and mood of the user and the amount taken. Feelings of relaxation, euphoria and a greater appreciation of sensory experiences are commonly described. When intoxicated cognitive and motor skills will be impaired. Psychological dependence on cannabis can develop and withdrawal symptoms, including restlessness, anxiety, irritability and insomnia, have been documented.

Cannabis induces feelings of anxiety and paranoia in some users. Depression may also be experienced. Heavy use can precipitate psychotic episodes but there is no evidence that cannabis use can lead to a psychotic illness which persists after abstinence, nor that cannabis is a causal factor in schizophrenia. However, recent evidence suggests that cannabis use increases the risk of schizophrenia and it can exacerbate symptoms. See Johns for a review of the psychiatric effects of cannabis. The physical health problems are mainly those associated with smoking tobacco. Research into the long-term effects of cannabis use is inconclusive.