Marijuana (cannabis) is the most commonly used illicit drug worldwide.
Classified as a Schedule 1 controlled substance, marijuana is a mood-altering (psychoactive) drug that affects almost every organ in the body. Marijuana has limited medical use for relief of severe pain, nausea, and other chronic conditions.
Surveys show that 11.7% of 8th graders and 35.1%of 12th graders in the US use marijuana and that close to 6% of 12th graders report daily use of the drug.1
According to the 2013 National Survey on Drug Use and Health (NSDUH), 19.8 million adults in the US used marijuana in the month prior to being surveyed, 81% of current illicit drug users had used marijuana, and it was the only drug used by 64.7% of current illicit drug users.2
Marijuana contains over 400 chemicals, with delta-9-tetrahydro-cannabinol (THC) the key psychoactive (mind-altering) substance in the drug. The possible effects of marijuana include mood changes, suicidal thinking and disruption to normal learning abilities. It may also be capable of producing dependency, psychosis and addiction.
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Fast facts on marijuana
Here are some key points about marijuana. More detail and supporting information are in the main article.
- The discovery of cannabis can be traced back to 2900 BC to the Chinese Emperor Fu Hsi.
- The potency of marijuana has more than doubled over the past 15 years.
- Its use, as well as its potency, is expected to expand as a result of its medical legalization in more than 20 states in the US.
- Marijuana can have both analgesic (pain-relieving) and antiemetic (anti-nausea) effects.
- Early adolescent use of cannabis can double the risk of schizophrenia and psychosis in some people.
- Around 1 in 10 of those who ever use cannabis become dependent on it.
- Most cannabis users stop using it in their mid-to-late twenties.
- Cannabis can be still be detected in the urine several months after use.
- The number of young people who believe that marijuana use is risky is decreasing.
- There have been no reported fatal overdoses directly related to the ingestion of cannabis.
What is marijuana?
Marijuana is derived from the dried flowering tops, leaves, stems and seeds of the Cannabis sativa (hemp) plant. Cannabis has been used for hundreds of years by humans, for fiber (hemp), seed oils, seed, medical treatment and recreationally.
Marijuana is derived from the Cannabis sativa plant and is sometimes used to treat chronic pain.
The hemp plant contains the psychoactive chemical delta-9-tetrahydro-cannabinol (THC). THC acts on specific brain cell receptors called cannabinoids. Immediately after smoking marijuana, THC can be detected in the blood.
Tests have shown THC has mild-to-moderate painkilling (analgesic) effects, and can be used for the treatment of pain. THC alters neurotransmitter release in the spinal cord, resulting in pain relief.
The compound is also known to stimulate appetite (informally known as "the munchies") and induce a relaxed state, as well has having effects on the person's sense of smell, hearing and eyesight. THC can also cause fatigue. In some people, THC may reduce symptoms of aggression.
Some limited studies have shown that THC shows promise for the treatment of nausea and vomiting - it may have antiemetic qualities that make it helpful as an adjunct therapy for people undergoing chemotherapy or other treatment where nausea can be a side effect.
Medical marijuana is used to treat chronic pain, muscle spasticity, anorexia, nausea and sleep disturbances. Medical marijuana is not subject to governmental standardization, making its ingredients and potency unknown.
There are several slang terms for cannabis as a recreational drug, including hash, hashish, grass, pot, weed, and dope. As a recreational drug, cannabis can come in a variety of forms, including:
- Unprocessed - dried flowers, leaves and stems
Marijuana can be smoked, inhaled through vapor, brewed as a tea, applied as a balm or eaten in a brownie or chocolate bar.
Effects of marijuana
The nature and effects of the more than 60 cannabinoids present in cannabis are largely unknown, but the most potent psychoactive agent identified is THC. When a person smokes cannabis, THC is quickly absorbed into the bloodstream, reaching the brain within minutes. The body absorbs THC more slowly when it is eaten, delaying the onset of action to up to two hours but prolonging the duration of the effect.
THC and other cannabinoids in marijuana are similar to cannabinoids produced by the body. These endogenous cannabinoids act like neurotransmitters that send chemical messages between nerve cells (neurons) throughout the nervous system.
Neurotransmitters affect brain areas involved in memory, thinking, concentration, movement, coordination and sensory and time perception as well as pleasure. The receptors that respond to these cannabinoids also respond to THC, which can alter and disrupt normal brain function.
THC has been seen to affect the hippocampus and orbitofrontal cortex - areas of the brain that control memory creation and attention. THC also disrupts the function of the cerebellum and basal ganglia, adversely affecting balance, posture, coordination and reaction time, which can make it unsafe for a person using marijuana to drive a car, operate heavy machinery or engage in sports or other potentially dangerous physical activities.
This agent also stimulates certain cannabinoid receptors that increase the release of dopamine, a neurotransmitter related to feelings of pleasure. This effect, common to many drugs of misuse (including heroin, cocaine, amphetamine and nicotine), may be the basis of its reinforcing properties and its recreational use. The effect is reversed by naloxone, suggesting an opioid link.
People use marijuana to achieve the feeling of elation (a high), giddiness and relaxation. Marijuana also produces sensory perception changes; colors may seem brighter, music more vivid and emotions more profound.
When cannabis is consumed for recreational purposes, the following effects are possible:
- Subjective change in perception - marijuana can have slight hallucinogenic effects, making users see reality in a distorted way
- Alteration in mood - some may experience euphoria, become more animated, while others enter a state of relaxation
- Increased heart rate
- Reduction in blood pressure
- Impairment of working memory
- Impairment of short-term memory
- Impairment of concentration
- Reduced psychomotor coordination
- Nausea (despite the fact that cannabis can treat the symptoms of nausea)
- Increase in appetite ("the munchies")
- More rapid breathing.
Depending on the length and amount of use, cannabis can still be detected in the urine for several months even after discontinuation.
On the next page we look at the hazards of marijuana and addiction to the drug.