Cannabis is the most widely used substance in the UK. Even though there has been a steady reduction of use since 1996, about 2.3 million 16-59 year-olds have reported using cannabis in the past year. Frequent use of cannabis is about twice as likely amongst young people, and nearly 5.3 million 16-24 year-olds have used it in the last year.
In spite of government and media warnings about health risks, many people see cannabis as a harmless substance that helps you to relax and ‘chill’ – a drug that, unlike alcohol and cigarettes, might even be good for your physical and mental health.
On the other hand, research over the last 10 years has suggested that it can have serious consequences for people, such as the development of an enduring psychotic illness, particularly in those who are genetically vulnerable.
What is cannabis?
Cannabis sativa and cannabis indica are members of the nettle family that have grown wild throughout the world for centuries. Both plants have been used for a variety of purposes including hemp to make rope and textiles, as a medical herb and as the popular recreational drug.
The plant is used as:
- The resin – a brown/black lump, known as bhang, ganja, hashish, resin etc;
- Herbal cannabis – made up of the dried flowering tops and variable amounts of dried leaves – known as grass, marijuana, spliff, weed etc…
Skunk refers to a range of stronger types of cannabis, grown for their higher concentration of the main active ingredient, namely THC (tetrahydrocannabinol). The name refers to the pungent smell they give off while growing. They can be grown either under grow-lights or in a greenhouse, often using hydroponic (growing in nutrient rich liquids rather than soil) techniques. There are hundreds of other varieties of cannabis with exotic names such as AK-47, Knock Out or Destroyer.
Over the last 15 years, skunk has invaded the street market and its THC content is about 2-3 times higher than the ‘traditional’ cannabis used in earlier years. In the UK, most sold materials is home grown because of a loop hole in the law making it legal to buy seeds over the internet.
How is it used?
Most commonly, the resin or the dried leaves are mixed with tobacco and smoked as a ‘spliff’ or ‘joint’. The smoke is inhaled strongly and held in the lungs for a number of seconds. It can also be smoked in a pipe, a water pipe, or collected in a container before inhaling it. It can be brewed as tea or cooked in cakes.
More than half of its psychologically active chemical ingredients are absorbed into the blood when smoked. These compounds tend to build up in fatty tissues throughout the body, so it takes a long time to be excreted in the urine. This is why cannabis can be detected in urine up to 56 days after it has last been used.
What is its legal status in the UK?
Cannabis was re-classified in January 2009 and is now a Class B drug under the Misuse of Drugs Act, 1971.
The maximum penalties are:
- For possession: 5 years prison sentence or an unlimited fine, or both
- For dealing/supplying:14 year prison sentence or an unlimited fine, or both.
Young people in possession of cannabis
A young person found to be in possession of cannabis will be:
- Taken to a police station
- Given a reprimand, final warning or charge, depending on the offence.
After one reprimand, a further offence will lead to a final warning or charge.
After a final warning:
- The young person must be referred to a Youth Offending Team to arrange a rehabilitation programme.
- A further offence will lead to a criminal charge.
Adults in possession of cannabis
This will usually result in a warning and confiscation of the drug. Some cases may lead to arrest and either caution or prosecution, including:
- repeat offending
- smoking in a public place
- threatening public order.
How does it work and what is the chemical make-up of cannabis?
There are about 400 chemical compounds in an average cannabis plant. The four main compounds are called delta-9-tetrahydrocannabinol (delta-9-THC), cannabidiol (CBD), delta-8-tetrahydrocannabinol and cannabinol. Apart from CBD, these compounds are psychoactive, the strongest one being delta-9-tetrahydrocannabinol. The stronger varieties of the plant contain little CBD, whilst the delta-9-THC content is a lot higher.
When cannabis is smoked, its compounds rapidly enter the bloodstream and are transported directly to the brain and other parts of the body. The feeling of being ‘stoned’ or ‘high’ is caused mainly by the delta-9-THC binding to cannabinoid receptors in the brain. A receptor is a site on a brain cell where certain substances can stick or “bind” for a while. If this happens, it has an effect on the cell and the nerve impulses it produces. Curiously, there are also THC-like substances produced naturally by the brain itself – these are called endocannabinoids. Even though chemically THC is not similar to the natural endocannabinoids, it can fit, like a key, into the same receptor lock and interferes with the normal functioning of the receptor.
Most of these receptors are found in the parts of the brain that influence emotion, pleasure, memory, thought, concentration, sensory and time perception. Cannabis compounds can also affect the eyes, the ears, the skin and the stomach.
What are its effects?
A ‘high’ – a sense of relaxation, happiness, sleepiness, colours appear more intense, music sounds better.
Even though THC can produce relaxation, if higher amounts are consumed, it can have the opposite effect by increasing anxiety. Some cannabis users may have unpleasant experiences, including confusion, hallucinations, anxiety and paranoia, depending on their mood and circumstances.
Some users may experience psychotic symptoms with hallucinations and delusions lasting a few hours, which can be very unpleasant. Even though these unpleasant effects do not last long, since the drug can stay in the system for some weeks, the effect can be more long-lasting than users realise.
Long-term use can have a depressant effect and reduce motivation. Some researchers also suggest that long-term use can lead to irreversible, but minor cognitive deficits.
Education and learning
There have also been suggestions that cannabis may interfere with a person’s capacity to:
- organise information
- use information.
This effect seems to last several weeks after use, which can cause particular problems for students.
However, a large study in New Zealand followed up 1265 children for 25 years. It found that cannabis use in adolescence was linked to poor school performance, but that there was no direct connection between the two. It looked as though it was simply because cannabis use encouraged a way of life that didn’t help with schoolwork.
It seems to have a similar effect on people at work. There is no evidence that cannabis causes specific health hazards. But users are more likely to leave work without permission, spend work time on personal matters or simply daydream. Cannabis users themselves report that drug use has interfered with their work and social life.
Of course, some areas of work are more demanding than others. A review of the research on the effect of cannabis on pilots revealed that those who had used cannabis made far more mistakes, both major and minor, than when they had not smoked cannabis. The pilots were tested in flight simulators, not actually flying… The worst effects were in the first four hours, although they persisted for at least 24 hours, even when the pilot had no sense at all of being ‘high’. It concluded “Most of us, with this evidence, would not want to fly with a pilot who had smoked cannabis within the last day or so”.
What about driving?
In New Zealand, researchers found that those who smoked regularly, and had smoked before driving, were more likely to be injured in a car crash. A recent study in France looked at over 10,000 drivers who were involved in fatal car crashes. Even when the influence of alcohol was taken into account, cannabis users were more than twice as likely to be the cause of a fatal crash than to be one of the victims.