FAQ about Cannabis

What is cannabis?

Cannabis is the most frequently abused illicit drug. A dry, shredded green/brown mix of flowers, stems, seeds, and leaves of the hemp plant Cannabis sativa, it is usually smoked as a joint, spliff, or in a pipe or bong. It also is smoked in blunts, which are cigars that have been emptied of tobacco and refilled with cannabis, often in combination with another drug. It might also be mixed in food or brewed as a tea. As a more concentrated, resinous form it is called hashish and, as a sticky black liquid, hash oil. Cannabis smoke has a pungent and distinctive, usually sweet-and-sour odor. There are countless street terms for cannabis including pot, herb, weed, grass, widow, ganja, and hash, as well as terms derived from trademarked varieties of cannabis, such as, Northern Lights, Rhino, Diesel Cheese, and a number of Skunk varieties. 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. The main active chemical in cannabis is THC (delta-9-tetrahydrocannabinol). The membranes of certain nerve cells in the brain contain protein receptors that bind to THC. Once securely in place, THC kicks off a series of cellular reactions that eventually lead to the high that users experience when they smoke marijuana.

What about skunk?

Traditional herbal cannabis contains between 1-15% of the main psycho-active ingredient, THC. Some of the newer strains, including skunk, contain up to 20%, so can be 3 times as strong as traditional cannabis. It works more quickly, and can create hallucinations with profound relaxation and elation – along with nervousness, anxiety attacks, projectile vomiting and a strong desire to eat. They may be used by some as a substitute for Ecstasy or LSD.

Legally, these strains remain classified Class B drugs. While there is little research so far, it is likely that these stronger strains carry a higher risk of causing mental illness. A major study currently underway, has already reported problems with concentration and short-term memory in users of stronger types of cannabis.

Cannabis effects on mental health?

There is growing evidence that people with serious mental illness, including depression and psychosis, are more likely to use cannabis or have used it for long periods of time in the past. Regular use of the drug has appeared to double the risk of developing a psychotic episode or long-term schizophrenia. However, does cannabis cause depression and schizophrenia or do people with these disorders use it as a medication? Recent research conducted in the UK strongly suggests that any casual link between cannabis and schizophrenia is extremely marginal – efficacy rates were reported at only at 2% window. However, individuals who do use cannabis and who have a history of mental health issues may find the specific disorder exacerbated significantly, not only by cannabis, but by the use of any mind or mood ordering chemical.

Over the past few years, research has strongly suggested that there is a clear link between early cannabis use and later mental health problems in those with a genetic vulnerability - and that there is a particular issue with the use of cannabis by adolescents.

Schizophrenia

Three major studies followed large numbers of people over several years, and showed that those people who use cannabis have a higher than average risk of developing schizophrenia. If you start smoking it before the age of 15, you are 4 times more likely to develop a psychotic disorder by the time you are 26. They found no evidence of self-medication. It seemed that, the more cannabis someone used, the more likely they were to develop symptoms.

Why should teenagers be particularly vulnerable to the use of cannabis? No one knows for certain, but it may be something to do with brain development. The brain is still developing in the teenage years – up to the age of around 20, in fact. A massive process of ‘neural pruning’ is going on. This is rather like streamlining a tangled jumble of circuits so they can work more effectively. Any experience, or substance, that affects this process has the potential to produce long-term psychological effects.

Recent research in Europe, and in the UK, has suggested that people who have a family background of mental illness – and so probably have a genetic vulnerability anyway - are more likely to develop schizophrenia if they use cannabis as well.

Is there such a thing as cannabis psychoses?

Fresh research suggests that yes, there is. It is a short-lived psychotic disorder that seems to be brought on by cannabis use but which subsides moderately quickly once the person has stopped using it. It's quite unusual though – in the whole of study they found only around 100 new cases per year.

However, they also found that: Three quarters had a different psychotic disorder diagnosed within the next year. Nearly half still had a psychotic disorder 3 years later. So, it also seems probable that nearly half of those diagnosed as having cannabis psychosis are in reality showing the first signs of a more long-lasting psychotic disorder, such as schizophrenia. It may be this group of people who are particularly vulnerable to the effects of cannabis, and so should probably avoid it in the future.

Cannabis effects on the heart?

One study has indicated that an abuser's risk of heart attack more than quadruples in the first hour after smoking cannabis. The researchers suggest that such an effect might occur from cannabis's effects on blood pressure and heart rate and reduced oxygen-carrying capacity of blood.

Cannabis effects on the lungs?

A study on individuals found that people who smoke cannabis frequently, but do not smoke tobacco have more health problems and miss more days of work than non-smokers. Many of the extra sick days among the cannabis smokers in the study were for respiratory illnesses.

Even infrequent abuse can cause burning and stinging of the mouth and throat, often accompanied by a heavy cough. Someone who smokes cannabis regularly may have many of the same respiratory problems that tobacco smokers do, such as daily cough and phlegm production, more frequent acute chest illness, a heightened risk of lung infections, and a greater tendency to obstructed airways. Smoking cannabis possibly increases the likelihood of developing cancer of the head or neck. A study comparing 173 cancer patients and 176 healthy individuals produced evidence that cannabis smoking doubled or tripled the risk of these cancers.

Cannabis abuse also has the potential to promote cancer of the lungs and other parts of the respiratory tract because it contains irritants and carcinogens. In fact, cannabis smoke contains 50 to 70 percent more carcinogenic hydrocarbons than tobacco smoke. It also induces high levels of an enzyme that converts certain hydrocarbons into their carcinogenic form—levels that may accelerate the changes that ultimately produce malignant cellar. Cannabis users usually inhale more deeply and hold their breath longer than tobacco smokers do, which increases the lungs’ exposure to carcinogenic smoke. These facts suggest that, puff for puff, smoking marijuana may be more harmful to the lungs than smoking tobacco.

Cannabis effects on the brain?

Scientists have learned a great deal about how THC acts in the brain to produce its many effects. When someone smokes cannabis, THC rapidly passes from the lungs into the bloodstream, which carries the chemical to organs throughout the body, including the brain.

In the brain, THC connects to specific sites called cannabinoid receptors on nerve cells and influences the activity of those cells. Some brain areas have many cannabinoid receptors; others have few or none. Many cannabinoid receptors are found in the parts of the brain that influence pleasure, memory, thought, concentration, sensory and time perception, and co-ordinate movement.

The short-term effects of cannabis can include problems with memory and learning; distorted perception; difficulty in thinking and problem solving; loss of coordination; and increased heart rate. Research findings for long-term cannabis abuse indicate some changes in the brain similar to those seen after long-term abuse of other major drugs. For example, cannabinoid (THC or synthetic forms of THC) withdrawal in chronically exposed animals leads to an increase in the activation of the stress-response system and changes in the activity of nerve cells containing dopamine. Dopamine neurons are involved in the regulation of motivation and reward, and are directly or indirectly affected by all drugs of abuse.

Effects of cannabis use on learning and social behavior?

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. As you can imagine, 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".

Cannabis other health effects?

Some of cannabis's adverse health effects may occur because THC impairs the immune system's ability to fight disease. In laboratory experiments that exposed animal and human cells to THC or other cannabis ingredients, the normal disease-preventing reactions of many of the key types of immune cells were inhibited. In other studies, mice exposed to THC or related substances were more likely than unexposed mice to develop bacterial infections and tumors. Two million people in the UK smoke cannabis. Half of all 16 to 29 year olds have tried it at least once. In spite of government warnings about health risks, many people see it 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, recent research has suggested that it can be a major cause of psychotic illnesses in those who are genetically vulnerable.

Cannabis addictive potential

Long-term cannabis abuse can lead to addiction for some people; that is, they abuse the drug compulsively even though it interferes with family, school, work and recreational activities. Drug craving and withdrawal symptoms can make it hard for long-term cannabis smokers to stop abusing the drug. People trying to quit report withdrawal symptoms of irritability, sleeplessness and anxiety. They also display increased aggression on psychological tests, peaking approximately one week after the last use of the drug.

Tolerance – having to take more and more to get the same effect, Withdrawal symptoms. These have been shown in heavy users and include: craving, decreased appetite, sleep difficulty, Weight loss, aggression and/or anger, Irritability, Restlessness, Strange dreams.

For regular, long-term users: 3 out of 4 experience cravings, half become irritable, 7 out of 10 switch to tobacco in an attempt to stay off cannabis. The irritability, anxiety and problems with sleeping usually appear 10 hours after the last joint, and peak at around one week after the last use of the drug.

Compulsive use

The user feels they have to have it and spends much of their life seeking, buying and using it. They cannot stop even when other important parts of their life, family, school and work suffer. You are most likely to become dependent on cannabis if you use it every day.