Cannabis is a psychoactive drug obtained from the dried, shredded leaves, flowers and stems of the hemp plant, Cannabis sativa. The effects of cannabis vary according to the type and quantity you take and how often you take it, but recreational cannabis users typically seek a state of altered consciousness, or ‘high’, during which they feel euphorically happy, relaxed and talkative.
The most active ingredient in cannabis – that is, the one most responsible for the typical effects of the drug – is a chemical compound called tetrahydracannabinol, or THC for short. When cannabis is inhaled, THC quickly enters the bloodstream and binds to specific receptors, known as cannabinoid receptors, in various areas of the brain. The cannabinoid receptors bring about the mood-altering effects of THC, stimulating neurons in the brain to release dopamine, a neurotransmitter, or chemical messenger, which, in sufficient quantities, makes you feel pleasure. Typically, a dose of 2-3mg of THC is sufficient to produce the desired effect.
Recreational cannabis users also often report heightened senses, which may cause colours to look more intense, or vivid, or make music sound inexplicably magical, while insatiable hunger pangs – commonly known as the ‘munchies’ – are also a common side effect. So, too, is a distorted perception of time, as a result of THC disrupting the normal functioning of cannabinoid receptors.
Some strains of cannabis or, indeed, cannabis that has been mixed, or ‘laced’, with another drug or drugs, may also cause visual or auditory hallucinations, in which you see or hear things that are not real. This temporary loss of contact from reality may be benign enough in itself, although it is produced by the same mechanism as hallucinations in severe mental health disorders, such as psychosis and schizophrenia, so may be a cause for concern if you have a family history of mental illness. To be clear, cannabis does not, necessarily, cause mental problems, but a genetic predisposition towards such problems may cause you to have an extreme, atypical reaction to the drug.
Cannabinoid receptors are also present in the parts of the brain responsible for concentration, coordination, learning, problem-solving and short-term memory, so all these functions can be severely impaired by cannabis. Activities such as driving are not only difficult, but downright dangerous, while under the influence of the drug and you’re twice as likely to be involved in an accident as a drug-free driver. Other unwelcome side effects of cannabis include dizziness, nausea, lethargy and general disinterest in yourself and the world around you, which can lead to careless grooming, withdrawal and the disintegration of your relationships with family and friends.
In the longer term, there is some scientific evidence that suggests cannabis can potentially cause mental health problems, such as anxiety, depression, panic attacks, paranoia, psychosis and schizophrenia. The evidence is by no means conclusive, but implies that mental health problems are more common if you smoke strong, high-potency cannabis, such as skunk or sinsemilla, rather than weaker strains. Aside from the active ingredients in cannabis, smoking the drug regularly over a long period, especially mixed with tobacco, increases you risk of cardiovascular and pulmonary diseases, including lung cancer, and stroke.