Marijuana: America’s Most Commonly Abused Drug

Street Names and Use of Marijuana
Marijuana has over 200 slang terms and is often called pot, grass, reefer, weed, herb, gangster, chronic, boom, Mary Jane, or MJ.

Joints or nails refer to the hand-rolled cigarettes containing marijuana. Pipes or water pipes called bongs are also used to smoke marijuana. Cigars with the tobacco replaced by marijuana are called blunts. Blunts often include another drug mixed with the marijuana like crack cocaine.

Marijuana is also used to brew tea and can be cooked in foods.

Signs of Marijuana Abuse
Someone under the influence of marijuana can often be recognized by the following signs:

Short-Term Effects of Marijuana
After smoking marijuana, the effects are felt within minutes. The high peaks in 10 to 30 minutes and can last for two to three hours. When marijuana is consumed in food or tea, it can take 30 to 60 minutes for the effects to be felt, and the effects of the marijuana will also last longer, up to 4 hours.

Low doses can produce the following effects:

Stronger doses of marijuana make the effects more pronounced:

Acute toxic psychosis is a risk with high doses of marijuana. This includes distorted images, delusions, and hallucinations. Depersonalization or confusion over the user’s own personal identity can occur. What exactly causes these symptoms is still unknown, but they seem to occur mostly in cases where a high dose of cannabis is consumed in food or drink, rather than smoked.

Marijuana effects a user experiences can depend on several factors. Research on twins has shown that identical twins are more likely than non-identical twins to have similar marijuana effects. While other factors, like the user’s expectations and the environment, also have important effects, genetics seem to play a role in determining the effects experienced.

The Typical Marijuana Response
The heart starts beating faster (20-50 beats per minute faster), bronchial passages relax and enlarge, and blood vessels expand in the eyes so they look red, all within minutes after smoking marijuana. The heart will beat even faster when other drugs are taken with marijuana.

THC stimulates brain cells to release the chemical dopamine, the same as most abused drugs do. This causes the high feeling. During this time, the marijuana user experiences pleasant sensations and intense colors and sounds. Time may seem to pass slowly. Marijuana may make the mouth feel dry and the user often becomes very hungry and thirsty. Their hands may get cold and shake.

After the feeling of euphoria passes, marijuana users become sleepy or feel depressed. Sometimes feelings of anxiety, fear, distrust, or panic set in.

How Marijuana Affects the Brain
As marijuana is inhaled or digested, the THC travels through the body and brain to produce the effects experienced.

In the brain, THC attaches to sites called cannabinoid receptors on nerve cells in the brain. Cannabinoids are naturally occurring cannabis-like chemicals in the body. Because THC molecules are similar to the cannabinoids, the THC interacts with the cannabinoid receptors, influencing many of the same processes. The THC overstimulates the cannabinoid receptors, disrupting the natural cannabinoids' control. This overstimulation produces the intoxication or high experienced by marijuana smokers. Over time, the THC may degrade some cannabinoid receptors, possibly producing permanent adverse effects and contributing to addiction and risk of withdrawal syndrome.

Many cannabinoid receptors exist in areas of the brain associated with movement, coordination, learning and memory, and higher cognitive functions such as judgment, and pleasure.

Parts of the brain particularly affected include:

In the following brain regions, there are a moderate amount of cannabinoid receptors, so these areas are affected moderately:

Marijuana and the Hippocampus
Recent research has shown that long-term use of marijuana produces changes in the brain similar to those produced by long-term use of other major drugs of abuse.

The hippocampus is the area of the brain that is crucial for learning, memory, and the integration of sensory experiences with emotions and motivations. The THC in marijuana changes how sensory information enters and is processed by the hippocampus, causing damage to short-term memory. THC suppresses neurons in the information processing system and the activity of the nerve fibers.

Research using laboratory rats supports this effect on the hippocampus. Those treated with THC had the same reduced short-term memory as those who had their nerve cells destroyed in their hippocampus.

Normally, as people get older, they lose neurons in the hippocampus. This makes it more and more difficult for them to remember things. Using marijuana repeatedly may speed up the loss of these neurons. A study that exposed rats to THC over time produced the same nerve cell loss of rats twice their age.

Effects of Marijuana on Physical Health
Chemicals and toxins in marijuana that cause cancer can be stored in fat cells for many months.

Extended use of marijuana increases risk to of suppression of the immune system, which may cause some adverse health effects. Marijuana may impair the immune system's ability to fight off infectious diseases and cancer. In laboratory experiments that exposed animal and human cells to THC or other marijuana ingredients, inhibition of the normal disease-preventing reactions of many of the key types of immune cells occurred. In other studies, it was shown that mice exposed to THC or related substances were more likely than unexposed mice to develop bacterial infections and tumors.

As reported consistently by NIDA's Community Epidemiology Work Group (CEWG), a network of researchers that tracks trends in the nature and patterns of drug use in major U.S. cities, marijuana is often combined with other drugs like crack cocaine, PCP, formaldehyde, and codeine cough syrup, sometimes without the user being aware of it. Therefore, the risks that come with marijuana use may be compounded by the risks of other drugs that are added to the THC.

The Drug Abuse Warning Network (DAWN), which monitors the health impact of drugs, estimated that marijuana was a contributing factor in more than 110,000 emergency department visits in the U.S. in 2001. Fifteen percent of the patients were between 12 and 17, and almost two-thirds male.

Effects of Marijuana on the Lungs
Smoking marijuana over time can lead to abnormal functioning of lung tissue, which is injured or destroyed by marijuana smoke. Usually when marijuana is smoked, the user inhales the unfiltered smoke deeply and holds it as long as possible for maximum effect. This keeps the smoke in extended contact with lung tissues. This can irritate and damage the lungs.

Even if someone smokes marijuana only every now and then, they can experience burning and stinging in their mouth and throat, sometimes with a heavy cough. Someone who smokes marijuana regularly may have many of the same respiratory problems as tobacco smokers but develop them faster:

Many marijuana users also smoke cigarettes, and the combination increases the health risk even more. The amount of tar and carbon monoxide absorbed by marijuana smokers is 3 - 5 times more than regular tobacco smokers, as they tend to inhale more deeply and hold the smoke in the lungs.

Marijuana use also makes it harder to quit smoking tobacco, especially for those who smoke marijuana daily.

Marijuana and Increased Risk of Cancer
Marijuana smoke can also promote cancer of the respiratory tract and lungs. A study comparing 173 cancer patients and 176 healthy individuals produced strong evidence that smoking marijuana increases the likelihood of developing cancer of the head or neck. The more marijuana smoked, the greater the likelihood. Statistical analysis of the data suggested that marijuana smoking doubled or tripled the risk of these cancers.

Marijuana contains irritants and carcinogens, so it has the potential to promote cancer of the lungs and other parts of the respiratory tract. Marijuana smoke actually contains 50 – 70% more carcinogenic hydrocarbons than tobacco smoke. It also produces high levels of an enzyme that converts certain hydrocarbons into carcinogens, potentially producing malignant cells. Because of the manner in which marijuana is smoked, the risk of cancer may much higher than that of smoking tobacco.

Effects of Marijuana on Heart Rate and Blood Pressure
Marijuana use can cause chest pain in people who have a poor blood supply to the heart. It increases the heart rate as much as 50 percent, depending on the amount of THC.

Marijuana and cocaine together can produce greater, longer-lasting cardiovascular effects than either drug alone. The result is severe increases in heart rate and blood pressure.

In a recent study, the heart rate increased 29 beats per minute with marijuana alone and 32 beats per minute with cocaine alone. When the drugs were given together, the heart rate increased by 49 beats per minute, and the increased rate persisted for a longer time. In the study, the subjects were sitting quietly – but if an individual were to do something physically stressful after taking both marijuana and cocaine, it may significantly increase risks of overload on the cardiovascular system.

Another study indicated that the risk of heart attack during the hour following smoking marijuana is 4 times the usual risk. This might occur partly because marijuana raises blood pressure and heart rate and reduces the oxygen-carrying capacity of blood.

Marijuana and Effects on Social Life
Marijuana use is characterized by depression, anxiety, and personality disturbances. Marijuana may cause problems in daily life or worsen existing problems.

The more a person uses marijuana, the more likely the person is to experience underdeveloped skills. Intellect, career, and social facets of life are affected by the compromised ability to learn.

Marijuana smokers who use marijuana heavily over long periods of time can become dull, slow moving, and inattentive. They often call this effect of prolonged use burnout. Often, burned out marijuana users become so unaware of their surroundings that they do not respond when friends speak to them, and they are not aware that they have a problem.

Children of parents who use marijuana exhibit more anger and regressive behavior such as thumb sucking and temper tantrums.

Marijuana use has also been linked to crimes committed by youths. The National Institute of Justice's Arrestee Drug Abuse Monitoring Program (ADAM) found that 39% of adult male arrestees and 26% of adult female arrestees tested positive for marijuana in 1999. In another study, ADAM collected data on juvenile arrestees in 9 places, finding that marijuana was the most commonly used drug among these youths. On average, 53% of juvenile male and 38% of juvenile female arrestees tested positive for marijuana.

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