Second only to alcohol, cannabis is the most popular and widely used drug in the United States. According to the National Survey on Drug Use and Health, 95 million Americans age 12 and older have tried pot at least once. By 2001, the proportion of under-18 users had increased by 67% since the 1960’s. Researchers attribute this to the significant increase of pro-drug messages in multimedia venues. Students of all ages today have access to the Internet where they can easily find websites that promote cannabis use, kits for beating drug tests, and can advertise and sell cannabis and paraphernalia. Meanwhile, the prevalence of higher potency cannabis (which is measured by the levels of THC delta-9-tetrahydrocannabinol) is increasing.

According to the Office of National Drug Control Policy, cannabis is much more powerful and so are the mind-altering effects associated with use. Average THC levels rose from less than one percent in the mid-1970s to more than six percent in 2002. This means that even what is considered just skunk weed, can be six to ten times more potent than what was available in the 60’s and 70’s. No cannabis is the same; dealers can mix cannabis with other substances, from oregano to being laced with PCP, which means you can’t rely on what you are getting. Sinsemilla potency increased in the past two decades from six percent to more than 13 percent, with some samples containing THC levels of up to 33 percent.

Is cannabis addictive? Is cannabis harmful? Is cannabis worse than alcohol?

Myth: Cannabis is not addictive

This manual began by addressing the myth that the first time someone uses they don’t usually experience the negative things that they have been told as a youth. This many times leads one to doubt the harmful effects and continue to use the drug. The most popular myth to explore is whether cannabis is addictive. For years it was believed that cannabis could not be addictive and many people today still hold that belief to be true. Current research supports that cannabis is both physically addictive and psychologically addictive.

Cannabis meets the criteria established by the American Psychiatric Association, and the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) for substance dependence. A person needs three of the following criteria occurring at any time in the same 12-month period to meet the diagnosis of dependency.

1) Tolerance: needing more of the substance to achieve the same effects, or diminished effect with the same amount of the substance. Individuals with heavy use of cannabis are generally not aware of having developed tolerance.

2) Withdrawal symptoms: with cannabis use this can be experienced as irritability, restlessness, loss of appetite, trouble with sleeping, weight loss, shaky hands and loss of motivation. Some people have displayed increased verbal and physical aggression after one week of not using cannabis.

3) Continuation of use despite the presence of adverse effects: a person continues to use even after they have hurt someone or themselves, have experienced suicidal ideation, relationship problems, etc. related to use.

4) Giving up social, occupational, or recreational activities because of the use of cannabis. Due to the progressive nature of these symptoms, the user does not recognize these changes despite comments and concerns of others. As the use of cannabis increases a person slowly changes their social group and activities with peers who use about the same if not more. This tends to normalize use for the person despite the increase in need.

5) The individual may withdraw from family activities and hobbies in order to use the substance in private or to spend more time with substance-using friends. Despite recognizing the role of the substance contributing to a psychological or physical problem the person continues use.

6) Cannabis is taken in larger amounts or over a longer period of time than intended.

7) There is a persistent desire or unsuccessful efforts to cut down or control substance use.

Symptoms of Cannabis Withdrawal

The THC from just one joint takes 7 days to get out of the body, and 42 days if someone is a daily user. Withdrawal starts 3 weeks after someone’s last dose.

According to a 2002 study by the U.S. Department of Health and Human Services, cannabis use has been shown to be three times more likely to lead to dependence among adolescents than among adults. Research by JC Gfroerer, and J.F. Epstein 1999 indicates that the earlier adolescents starts using cannabis, the more likely they are to become dependent on this or other illicit drugs later in life. This does not mean cannabis is a gateway drug, but early use can be one of numerous factors that influence future use.

Progression of Cannabis Use

• Experimentation, trying a substance for the first time, and occasion
• Social- no pattern, minimal impact
• Habituation- established pattern of use
• Abuse- pattern of use and continued use despite negative consequences
• Addiction- continued use despite negative consequences, compulsion to use, loss of control, withdrawal, and desire to use again after withdrawal.

Myth: cannabis is not as harmful as other substances.

It is important to look at the acute effects of cannabis use. Immediately after the drug enters the brain, the effects begin and can last from one to three hours. If cannabis is consumed in food or drink, the short-term effects begin more slowly and last longer. Smoking cannabis deposits several times moreTHC into the blood than does ingesting the drug.

In the minutes following inhalation the heart begins beating more rapidly, usually increasing by 20 to 50 beats per minute. The bronchial passages relax and become enlarged, and blood vessels in the eyes expand, making the eyes look red. THC begins to enter the brain causing the euphoric “feeling high” – by acting on the brain’s reward system. THC activates the reward system much the same as nearly all drugs, by stimulating brain cells to release the chemical dopamine. The THC effects on the brain disrupt balance, posture and coordination of movement and reaction time. Sensations, colors and sounds may seem more intense and time seems to pass more slowly. Users tend to experience dry mouth, hunger and thirst. The hands can become cold and may tremble. After the euphoria passes users can feel sleepy or depressed. On occasion cannabis can produce anxiety, panic, fear or distrust as the euphoria dissipates.

High doses of cannabis have been known to cause acute toxic psychosis, which include hallucinations, delusions and depersonalization (loss of the sense of personal identity or self-recognition). These symptoms tend to occur more frequently in high doses that are consumed in food or drink rather than smoked. (Graham, A.W.; Schultz, T.K.; and Wilford, B.B. (eds.). Principles of Addiction Medicine, 2nd Edition. Chevy Chase, MD: American Society of Addiction Medicine, Inc., 1998. Gilman, A.G.; Rall, T.W.; Nies, A.S.; and Taylor, P. (eds.). Goodman and Gilman’s The Pharmacological Basis of Therapeutics, 8th Edition. New York: Pergamon Press, 1998

Effects of Cannabis on the Brain

The impact of cannabis use on short-term memory seems to occur because THC alters the way in which information is processed by the hippocampus, a brain area responsible for memory formation. As people age, they normally lose neurons in the hippocampus, which decreases their ability to remember events. Chronic THC exposure may hasten the age-related loss of hippocampal neurons. (http://www.drugabuse.gov/ResearchReports/Marijuana/Marijuana3.html)
A study done by McLean Hospital in Belmont, Massachusetts showed that cognitive impairment among college students who were regular users of cannabis (had used 27 of the last 30 days) had impaired skills related to attention, memory and learning for up to 24 hours after they last used the drug. These students had difficulty in sustaining and shifting attention and in registering, organizing and using information than the control group. A more recent study by this same group showed that the ability of a group of long-term heavy cannabis abusers to recall words from a list remained impaired for a week after quitting, but returned to normal within 4 weeks of quitting. Another study conducted at the University of Iowa College of Medicine found that people who used cannabis frequently (seven or more times weekly for an extended period) showed deficits in mathematical skills and verbal expression, as well as selective impairments in memory-retrieval process. (Block, RI and Ghoneim, MM Effects of chronic cannabis use on human cognition. Psychopharmacology. 110(1-2):219-228, 1993.)

When cannabis is smoked, its active ingredient, THC, travels throughout the body, including the brain, to produce its many effects. THC attaches to sites called cannabinoid receptors on nerve cells in the brain, affecting the way those cells work. Cannabinoid receptors are abundant in parts of the brain that regulate movement, coordination, learning and memory, higher cognitive functions such as judgment, and pleasure.
If you are interested in accessing a chart which describes the effects on each region of the brain please checkout the following website:

http://www.drugabuse.gov/ResearchReports/Marijuana/Marijuana3.html

Effects on the Lungs

Researchers at the University of California, Los Angeles, have determined that cannabis smoking can cause potentially serious damage to the respiratory system at a relatively early age. For years, it has been known and research supports that cannabis contains the same cancer causing chemicals that are found in tobacco. Puff for puff the amount of tar inhaled and the level of carbon monoxide regardless of THC content are three to five times greater than among tobacco smokers. Regular users of cannabis often have the same breathing problems as tobacco users, such as chronic cough and wheezing, and experience more respiratory infections and acute chest illnesses.
A study of 450 individuals found that people who smoke cannabis frequently but do not smoke tobacco have more health problems and miss more days of work than nonsmokers. Many of the extra sick days used by cannabis smokers in the study were for respiratory illnesses. (Polen, M.R; Sidney, S.; Tekawa, I.S.; Sadler. M.; and Friedman, G.D. Health care use by frequent cannabis smokers who do not smoke tobacco. West J Med 158:596-601, 1993.)

Even recreational use of cannabis 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.
According to a study by D.P. Tashkin (West J Med 152:525-530, 1990), cancer of the respiratory tract and lungs may also be promoted by cannabis smoke. A study comparing 173 cancer patients and 176 healthy individuals produced strong evidence that smoking cannabis increases the likelihood of developing cancer of the head or neck, and that the more cannabis smoked, the greater the increase. A statistical analysis of the data suggested that smoking cannabis doubled or tripled the risk of these cancers. (Zhang, Z.-F.; Morgenstern, H.; Spitz, M.R.; Tashkin, D.P.; Yu, G.-P.; Marshall, J.R.; Hsu, T.C; and Schantz, S.P. Marijuana use and increased risk of squamous cell carcinoma of the head and neck. Cancer Epidemiology, Biomarkers & Prevention 6:1071-1078, 1999.)
Cannabis contains 50 to 70 percent more carcinogenic hydrocarbons than does tobacco giving it the potential to promote cancer of the lungs and other parts of the respiratory tract. It also produces high levels of an enzyme that converts certain hydrocarbons into their carcinogenic form, which may accelerate the changes that ultimately produce malignant cells. 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 cannabis may increase the risk of cancer more than smoking tobacco does. (Cohen, S. Adverse effects of cannabis: Selected issues. Annals of the New York Academy of Sciences 362:119-124, 1981.)
Some adverse health effects caused by cannabis may occur because THC impairs the immune system’s ability to fight off infectious diseases and cancer.

Health Consequences of Cannabis Abuse
Acute (present during intoxication)

• Impairs short-term memory
• Impairs attention, judgment, and other cognitive functions
• Impairs coordination and balance
• Increases heart rate

Persistent (lasting longer than intoxication, but may not be permanent)

• Impairs memory and learning skills
• Impairs motivation

Long-Term (cumulative, potentially permanent effects of chronic abuse)

• Can lead to addiction
• Increases risk of chronic cough, bronchitis, and emphysema
• Memory problems
• Increases risk of cancer of the head, neck, and lungs
• Decreased sperm count and levels of testosterone
• Difficulty in the ability to conceive
• Chromosome damage

Adverse Social Effects

Numerous research and personal reports from regular to chronic users of cannabis, report that use of cannabis has caused problems in a person’s daily life or caused existing problems to get worse. Depression, anxiety, a change in motivation, and a potential for violence or increased aggression are among the more serious problems that can occur socially from use of cannabis. On a personal level a recreational to chronic user can experience relational problems, occupational and learning problems, absenteeism and or memory problems. Later teen users also tend to have more sexual partners and are more likely to engage in unsafe sex. (Brook, J.S. et al. The risks for late adolescence of early adolescent cannabis use. American Journal of Public Health, October 1999.)

Myth: Cannabis is Not as Bad as Alcohol.

Symptoms of Abuse of Cannabis and Alcohol

Behavioral symptoms of an alcohol abuser and cannabis abuser are very much the same. In studies comparing college students who abuse alcohol and those that abuse cannabis on a regular basis, both missed classes because of use, tended to sleep more, had a change in attentiveness and concentration, were more irritable, struggled with motivation to be involved in other things, had an uncertainty about future goals and their academics seemed to suffer to different degrees. These studies opened up further exploration to what was once termed “amotivational syndrome” with cannabis users. People with “amotivational syndrome” basically “stand still.” They tend to struggle with future plans, commitments, and may underachieve at academics and performance in work. Studies indicate these same symptoms tended to be present with students who had abusive patterns with alcohol. It is unclear if cannabis or alcohol use caused the syndromes or behavior, or if a persons personality characteristics made abuse of substances more attractive.

The debate between which drug is worse than the other has been a significant argument between alcohol and cannabis users for decades. The reality is that both pose significant risk, especially to young people. Both cause a great deal of cost to society in terms of crime, lost productivity, tragedies and deaths. Both have significant health risks, and both have significant negative social impacts on learning, occupational performance and relationships.

Over the last ten years significant attention has been devoted to reducing traffic deaths related to drunk driving. This attention has diverted focus on the fact that cannabis use is just as critical in regard to traffic accidents, injuries and deaths. As mentioned earlier, THC disrupts coordination and balance by binding to receptors in the cerebellum and basal ganglia, parts of the brain that regulate balance, posture, coordination of movement and reaction time. Through its effects on the brain and body, cannabis intoxication does cause accidents. A driver’s thought process and reflexes are slowed, making it difficult to respond to sudden, unexpected events. A driver’s ability to “track” (stay in lane) through curves, to brake quickly, and to maintain speed and the proper distance between cars is affected. Research shows that these skills are impaired for at least four to six hours after smoking a single cannabis cigarette, which may be long after the “high” is gone. Studies show that approximately 6% to 11% of fatal accident victims test positive for THC. In many of these cases, alcohol is detected as well. Fifteen percent of trauma patients who were injured while driving a car or motorcycle had been smoking marijuana and 17% of trauma patients have both alcohol and THC present in their blood. (Mason, A.P., and McBay, A.J. Ethanol, marijuana, and other drug use in 600 drivers killed in single-vehicle crashes in North Carolina, 1978-1981. J Forensic Sci 29(4):987-1026, 1984. Williams, A.F.; Peat, M.A.; Crouch, D.J.; Wells, J.K.; and Finkle, B.S. Drugs in fatally injured young male drivers. Public Health Report 100(1):19-25, 1985.Cimbura, G.; Lucas, D.M.; Bennett, R.C.; and Donelson, A.C. Incidence and toxicological aspects of cannabis and ethanol detected in 1,394 fatally injured drivers and pedestrians in Ontario (1982-1984). J Forensic Sci 35(5):1035-1041, 1990.)
In a study conducted by the National Highway Traffic Safety Administration, a moderate dose of cannabis alone was shown to impair driving performance; however, the effects of even a low dose of cannabis combined with alcohol were markedly greater than for either drug alone. Driving indices measured included reaction time, visual search frequency (driver checking side streets), and the ability to perceive and/or respond to changes in the relative velocity of other vehicles. For example, the disruptive effect that cannabis has on coordination may last for more than 24 hours, which is far beyond the period of subjective intoxication. Losken A, Maviglia S, Friedman LS. Marijuana. In: Friedman LS, et al., eds. Source book of substance abuse and addiction. Baltimore, Md.: Williams & Wilkins, 1996:179-87.

Another common belief is that the high a person gets from cannabis has a mellowing effect on the user. This is not always true. Adolescents that use cannabis weekly are nearly four times more likely than non-users to report they engage in violent or aggressive behavior. This behavior is described as physically attacking people, stealing and destroying property. Studies have indicated that the amount of violence by a person seems to increase in proportion to the number of days cannabis was smoked in the past year. Users were also twice as likely as non-users to report that they disobey at school and destroy their own things. (Greenblatt, J. Adolescent self-reported behviors and their association with cannabis use. Substance Abuse and Mental Health Services Administration (SAMHSA). Based on data from the National Household Survey on Drug Abuse, 1994-1996, 1998.)

Additional Information:

Cannabis has often been referred to as a gateway drug. The majority of research does not support cannabis as a gateway to other substances. Other factors seem to be more of an indicator than the substance itself. Age, for example, can be an indicator because the earlier an adolescent begins to use substances, the more likely they will move on to other drugs. Environment also plays a lead role by influencing availability of drugs and access to other drug users.
Medical use of cannabis is also under constant debate. Synthetic THC is the main ingredient in Marinol (pill form), an FDA-approved medication used to control nausea in cancer chemotherapy patients and to stimulate appetite in people with AIDS. Marinol has been approved as a safe version of medical cannabis and has been available by prescription since 1985. Research is still underway to examine such things as its use for pain and treatment of spasticity due to multiple sclerosis.

Bibliography of information:
Bibliography
Block, RI and Ghoneim, MM Effects of chronic marijuana use on human cognition. Psychopharmacology. 110(1-2):219-228, 1993.)
Brook, J.S. et al. The risks for late adolescence of early adolescent marijuana use. American Journal of Public Health, October 1999.)
Cohen, S. Adverse effects of marijuana: Selected issues. Annals of the New York Academy of Sciences 362:119-124, 1981.)
Confronting Marijuana Use www.bacchusgamma.org

Graham, A.W.; Schultz, T.K.; and Wilford, B.B. (eds.). Principles of Addiction Medicine, 2nd Edition. Chevy Chase, MD: American Society of Addiction Medicine, Inc., 1998. Gilman, A.G.; Rall, T.W.; Nies, A.S.; and Taylor, P. (eds.). Goodman and Gilman’s The Pharmacological Basis of Therapeutics, 8th Edition. New York: Pergamon Press, 1998

Greenblatt, J. Adolescent self-reported behviors and their association with marijuana use. Substance Abuse and Mental Health Services Administration (SAMHSA). Based on data from the National Household Survey on Drug Abuse, 1994-1996, 1998.)

Losken A, Maviglia S, Friedman LS. Marijuana. In: Friedman LS, et al., eds. Source book of substance abuse and addiction. Baltimore, Md.: Williams & Wilkins, 1996:179-87.

Marijuana Myths and Facts, The Truth Behind 10 Popular Misperceptions www.whitehousedrugpolicy.gov.
Mason, A.P., and McBay, A.J. Ethanol, marijuana, and other drug use in 600 drivers killed in single-vehicle crashes in North Carolina, 1978-1981. J Forensic Sci 29(4):987-1026, 1984. Williams, A.F.; Peat, M.A.; Crouch, D.J.; Wells, J.K.; and Finkle, B.S. Drugs in fatally injured young male drivers. Public Health Report 100(1):19-25, 1985.Cimbura, G.; Lucas, D.M.; Bennett, R.C.; and Donelson, A.C. Incidence and toxicological aspects of cannabis and ethanol detected in 1,394 fatally injured drivers and pedestrians in Ontario (1982-1984). J Forensic Sci 35(5):1035-1041, 1990.)

NIDA-Research Report Series – Marijuana Abuse http://drugabuse.gov/ResearchReprots/Marijuana/Marijuana3.html

Polen, M.R; Sidney, S.; Tekawa, I.S.; Sadler. M.; and Friedman, G.D. Health care use by frequent marijuana smokers who do not smoke tobacco. West J Med 158:596-601, 1993.)