Epidemiology: Use and Demographic Trends
is the most consumed illegal substance in the
youth in the \x9170\x92s used marijuana in high numbers, up to 60% of 12th
graders in 1979 had tried the drug.\xA0 In
1992, that number fell to 33% and then rose again to 50% in 1997 (23).\xA0 These rates have leveled off and currently,
according to the 2004
\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0 In 2003, the National
Survey on Drug Use and Health (NSDUH) showed that more than 40% of Americans
age 12 and older had tried using marijuana (23).\xA0 During a 1999 meeting of the Community
Epidemiology Work Group which tracks effects of drug abuse in different
the previous year, 5% had smoked in the previous month, and less than 5% were using every week (7).
\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0 Rates of marijuana use
vary between different races and genders, and not only in different age
groups.\xA0 Among adolescents, male and
Hispanic students showed higher rates of drug use on school grounds, than
female and white students (9).\xA0 Different
countries show different rates of use as well.\xA0
In a study of 31 countries, lifetime cannabis use was highest in
Marijuana as a Substance
RISKS AS PERTAINS TO ABUSE
\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0 Studies show that individuals involved in chronic marijuana use show the same kinds of respiratory symptoms as tobacco smokers.\xA0 These include coughing, wheezing, and bronchitis (38).\xA0 Smoking tobacco at the same time therefore may have even increased risks for lung problems, but another downside is that marijuana has been shown to make quitting tobacco more challenging (10).\xA0 One study showed that employees who smoke marijuana miss more days of work and report increased health problems, mostly due to respiratory illnesses (23).\xA0
\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0 Just as marijuana shows similar respiratory changes as tobacco, it also shows similar cellular changes in the bronchial tract which are pre-cancerous (138).\xA0 These similar changes are for regular marijuana use and regular tobacco use.\xA0 Regular marijuana use is defined as a smaller amount smoked than regular tobacco use, which implies that marijuana is in fact more damaging to the respiratory tract than tobacco (34).\xA0 Also, the carcinogenic hydrocarbons found in marijuana smoke are 50 to 70% greater than in tobacco smoke (23).\xA0 These changes increase the tendency to develop lung cancer, and imply that marijuana may pose as a similar or greater risk factor than tobacco although more epidemiological evidence is needed.
has been shown to increase cancer of the head and neck in some studies.\xA0 Dr. Daniel Ford of
\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0 Studies also show that marijuana may increase the risk of transitional cell carcinoma, a cancer found mostly in the bladder (6).\xA0 This was seen for men aged less than 60 years. \xA0\xA0\xA0\xA0
\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0 Marijuana use is often associated with memory loss and learning disabilities.\xA0 Various studies have been done to prove or disprove this correlation.\xA0 Differences occur between effects of acute marijuana use and chronic long-term use on cognition.
\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0 Studies on acute effects show that what is most likely affected is distance and time perception (time seems to lengthen and distance seems to increase between objects), vision (more difficult to discriminate colors), complex reaction time, recognition memory,
and recall (7).\xA0 In summary, simple tasks are not affected but more complex tasks, especially those requiring rapid thinking are.
Rats that are exposed to THC, the active ingredient in marijuana, have less of an ability to use short-term memory. \xA0These same effects are seen in rats that have a part of their brain destroyed in the hippocampal region which is involved in short-term memory (23).\xA0
\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0 Studies on chronic use showed less gross effects on neuropsychological impairments such as those seen with alcohol abuse, but some highly sensitive tests show difficulty in transferring information from short-term memory to long-term memory (7).\xA0 A very well-controlled study showed differences in brain waves in chronic marijuana users when performing difficult tasks.\xA0 These users could not process information as rapidly (31).
\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0 Other studies demonstrate learning deficits in heavy users of marijuana, but often these cognitive abilities can be regained after abstinence (26).\xA0 A meta-analysis showed that long-term use was not associated with generalized neurocognitive decline except for a small decline in the capability of learning new information (12).
\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0 There are important differences seen in the adolescent age group in terms of cognition.\xA0 One study showed that adults who began smoking marijuana before age 17 had smaller brains, a lower percentage of gray matter \x96 which is the substance of the brain, and a higher percentage of white matter \x96 which is the conducting system of the brain, than adults who had not (36). \xA0Another study showed that someone who begins smoking at age 13 will earn less money and will have completed less education as a young adult (8).\xA0 This could possibly be associated with deficits in cognition.\xA0 Marijuana use may impact brain development in a critical period, and that suggests that adolescents using marijuana should have more targeted precautions for use.\xA0
\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0 Mice exposed to THC were shown to have an impairment of immune function which reduced their ability to slow tumor growth and fight infections (27).\xA0 More research is needed to determine whether marijuana reduces the same capabilities in humans.
\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0 Acute effects of marijuana include an increase in heart rate and blood pressure.\xA0 One study shows that the risk of heart attack immediately after smoking marijuana is four times greater.\xA0 This is especially significant for older individuals who have an increased risk
of a cardiovascular event such as heart attack or stroke due to age.\xA0 A review of studies on
cardiovascular risks of cannabis showed that in fact the cardiac effects of marijuana do not pose a risk for young otherwise healthy individuals, but do for older people (19).\xA0
Risks with pregnancy
\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0 There are specific risks which have been associated with marijuana use during pregnancy.\xA0 Neonates of women using marijuana develop certain characteristics which reflect possible problems in neurological development.\xA0 Young children grow to more often experience symptoms of inattention and impulsivity associated with Attention Deficit Hyperactivity Disorder (ADHD), and also some deficits in learning and memory (18).\xA0
\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0 Marijuana has also been shown to decrease fertility in men by decreasing the effectiveness of sperm in fertilizing an egg (29).
\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0 In 2000, Iversen reported that there had been no deaths from THC overdose.\xA0 Animal studies show that an extremely high and improbable amount of joints would need to be smoked in order to achieve toxic levels.\xA0 Nonetheless, marijuana is still a somewhat frequent factor involved in emergency visits.\xA0 In 2002, marijuana was a contributing factor in 15% of ED visits in 12\x9617 year olds for unspecified causes (33).\xA0 Certain studies show that 6-11% of fatal accident victims test positive for THC but they often test positive for alcohol as well. \xA0\xA0
\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0 The National Highway Traffic Safety Administration advises against driving while under the influence of marijuana.\xA0 A study they conducted showed that marijuana impaired driving performance, but especially when combined with alcohol, showing a greater effect than alcohol alone (25).\xA0 On the other hand, lab studies show that marijuana users compensate for driving inadequacies by driving slower and keeping a greater distance between cars so that they are less likely to cause an accident and epidemiological studies confirm this (1).\xA0 This compensation though may not be sufficient when rapid thinking is needed in a driving situation, and as described in the section on cognition, rapid thinking is impaired under acute intoxication.\xA0 \xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0
MENTAL HEALTH/SOCIAL HEALTH
Mental Health Damage
\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0 Marijuana abuse has frequently been associated with depressive and even psychotic symptoms but it is often unclear as to whether these mental health disorders are caused by marijuana, self-medicated by marijuana, or are explained by outside factors.\xA0 Marijuana intoxication can produce behaviors that are schizophrenic in nature, but these behaviors go away after acute use (14).\xA0 One review claims that studies do point to an association between psychosis and marijuana use and proposes a biological explanation, referencing studies which show increases in psychosis not explained by other factors (13).\xA0 Another explanation may be that people with mental illnesses self-medicate with marijuana.\xA0 A New Zealand study showed that people with mental illness are 15 times more likely to use marijuana at age 18 (7).
\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0 Other studies show associations with depressive symptoms, defined by a certain amotivational syndrome, where individuals do not achieve the same educational and behavior goals as others with similar characteristics.\xA0 Research shows that there are not differences in school performance in college students who use and don\x92t use marijuana (38), but that high school students who use marijuana have lower grades, quit school more often, and spend less time on homework (20).\xA0 A causal relationship is refuted by a study that shows poor school performance prior to initiating marijuana use (30).\xA0 There may be a reason explaining both poor school performance and increased marijuana use and this reason could possibly be increased deviant behavior.\xA0 These individuals may have oppositional defiant disorder, associated with breaking the rules.\xA0 Because marijuana is illegal and easily accessed, it may just represent another rule that can be broken.
\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0 A job-related study supports amotivational syndrome.\xA0 Workers who smoke marijuana have a 75% increase in absenteeism.\xA0 Also of note is a 55% increase in industrial accidents and 85% increase in injuries on the job (23).\xA0
\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0 When controlling for income and family of origin, one study found that marijuana users were less likely to complete college and were more likely to have an income of less than $30,000 than their peers.
\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0 Another correlation with depressive symptoms is demonstrated by a study which showed that people who smoke marijuana before the age of 17 are 3.5 more likely to attempt suicide as those who start later.\xA0 Also, the same study showed that marijuana dependent individuals have a higher prevalence of major depressive disorder (22).\xA0 As stated before for psychotic symptoms, the causal relationship is unclear.
\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0 Sometimes marijuana use can lead to dependence and problems with addiction.\xA0 Dependence according to the DSM-IV, the diagnostic manual of psychiatrists, dependence requires 3 of 7 symptoms in the same year.\xA0 These symptoms include tolerance, withdrawal, using more than intended, being unable to cut down, increasing the time spent using, giving up other life activities, and using despite consequences.\xA0 The 2003 National Drug Use and Health (NSDUH) study reports that 4.2 million Americans are dependent or abusing marijuana (23).\xA0 Of 42,000 people surveyed in a 1998 study, 23% were diagnosed with abuse and 6% were diagnosed with dependence.
\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0 \xA0Marijuana smokers do experience withdrawal symptoms, although often these are not as physical as those for other illicit drugs such as cocaine and heroin.\xA0 These withdrawal symptoms include irritability, a depressed mood, lack of appetite, cravings, anger, and restlessness.\xA0 These symptoms can be as severe as tobacco withdrawal (4).
\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0 People sometimes associate marijuana with aggressive behavior.\xA0 In fact, laboratory test show that an increased THC level does not increase competitive behavior in test subjects (24), although sometimes withdrawal symptoms may include aggression (21).\xA0 The 2002 National Institute of Justice\x92s Arrestee Drug Abuse Monitoring Program found that of arrested individuals, 41% of males and 27% of females were found to test positive for marijuana (7).\xA0 This may not point to a causal relationship since many of the same people tested positive for other illicit drugs or alcohol.\xA0 A NIDA Research summary provides evidence which supports that often marijuana is combined with other illicit drugs, and this may contribute to the aggressive behavior.
\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0 A highly debatable topic is whether or not marijuana is a gateway drug, or a drug which once initiated, leads to the use of other drugs, which are often more harmful and addictive.\xA0 Data from the Substance Abuse and Mental health Services Administration in 2000 showed that of those who have tried marijuana, 77% have tried crack, 33% have tried cocaine, and 3.9% have tried heroin.\xA0 Although most users of hard drugs try marijuana first, most of marijuana users do not try hard drugs (7).\xA0 There are different explanations for why these associations exist.\xA0 One is that users of marijuana, by virtue of marijuana being an
illegal drug, will also be exposed to a market of other illegal drugs, which is less likely for someone who abuses alcohol or tobacco, which are legal.\xA0 Another explanation is that some marijuana users exhibit deviant behavior which motivates them to abuse illegal substances and therefore influences the use of both marijuana and other illicit drugs.\xA0 Another theory is that there may be pharmacological effects associated with marijuana use which increase the likelihood of use of other illicit drugs.\xA0 An experiment performed in 1997 demonstrated that rats exposed to THC did not show a greater propensity to push levers for other drugs (28).\xA0 On the other hand, a dose-response relationship was found by researchers correlating the amount of marijuana use at age 16 with alcohol and other substance use by age 18 (13).\xA0 One paper suggests that animal studies which show similar neurological effects of cannabis and cocaine and heroin suggest that use of one may influence the use of another (13). \xA0\xA0
\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0 Project MATCH, a 1998 comparative study of cognitive behavioral therapy, 12-step facilitation, and motivational interviewing showed that all three treatment approaches showed comparable effectiveness in treating marijuana addiction.\xA0 The author of the study cited previously on effects of withdrawal suggests that marijuana abusers trying to quit should be informed of what to expect in terms of withdrawal symptoms in order to normalize the process and treat some of the symptoms involved in order to decrease the likelihood of relapse (4).\xA0 Another author previously cited when discussing increased rates of suicide and depressive symptoms associated with marijuana use, argues that although a causal relationship is unclear, what is clear is the likelihood for other mental disorders in a marijuana abuser and it is important for those to be addressed at the same time as the addictive symptoms (22).
\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0 One possible treatment option that is not available yet is medication.\xA0 Some illegal drug use is able to be medicated by drugs which conflict with the actions of the illicit drug and therefore either reduce the response, or produce an undesired response in order to reduce the desire to use the illicit drug.\xA0 One drug currently being studied called SR141716 shows the same effects for marijuana, and blocks the receptors which marijuana binds to in humans (17).\xA0 This development poses new options for abusers of marijuana who require treatment. \xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0
\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0 Some research shows that outpatient interventions associated with social support show some of the best improvements in marijuana addiction (7).\xA0 Other research demonstrates the effectiveness of voucher programs, where individuals are compensated with gifts for abstaining from drug use (3).\xA0 In 2001, an evaluation of 23 community-based adolescent treatment programs found a decrease from 80% to 44% of weekly marijuana use, fewer thoughts of suicide, higher self-esteem, and better school performance (16).\xA0
\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0\xA0 The aforementioned risk of
marijuana use specifically associated with adolescents emphasizes the need for
preventive efforts against early use and any time abuse of marijuana.\xA0 Educational programs such as the well-known
police enforced DARE program have been shown to be ineffective.\xA0 The best preventive methods employ social
influence such as changing social norms so that individuals understand the
reality of the drug environment and that not \x93everyone is doing it\x94, teaching
drug refusal skills, and using cognitive behavioral skills to make decisions
based on pros and cons (7).\xA0 In rural
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