Running head: DRUG ABUSE 1

Understanding Marijuana

Myrna Davis Washington

University of the Rockies

DRUG ABUSE 2

Abstract

According to the National Institute of Drug Addiction (NIDA,

2011), drug addiction is defined as a chronic relapsing brain

disease expressed in the form of compulsive behaviors. With over

29 million users in the United States in 2010, marijuana is the

most popular and commonly-abused illicit drug in the United

States. Yet, marijuana has a low addiction rate and is rarely

accompanied by withdrawal symptoms. This paper explores and

clarifies the current understanding of marijuana by examining how

marijuana is abused, its additional adverse effects on mental and

physical health and daily living, current treatment options for

marijuana dependence, and current trends in its use and addiction

research. Current issues in marijuana research indicate that

marijuana addiction is psychologically-complex, that it is a

disturbance of decision making, that it is not limited to drugs,

and that it involves many transmitters.

DRUG ABUSE 3

Understanding Marijuana

Although twentieth-century research on the nature of drug

abuse was filtered through the perceptual sieve of powerful myths

and misconceptions, today’s scientific research has dramatically

altered the current views and responses to drug addiction by

making groundbreaking discoveries about the mechanisms of the

brain that have revolutionized the understanding of drug abuse

and addiction as a chronic relapsing brain disease expressed in

the form of compulsive behaviors (National Institute of Drug

DRUG ABUSE 4

Abuse [NIDA], 2011). As a result of current research, scientists

have now identified many of the biological and environmental

factors of drug abuse and are beginning to search for the genetic

variations that contribute to the development and progression of

the disease (NIDA, 2011). Although this knowledge has enabled

scientists to develop effective prevention and treatment

approaches that reduce the toll drug abuse takes on individuals,

families, and communities, it has not only raised a number of

issues that have been the focus of current research, but has left

a gap in the understanding as to why individuals become addicted

to certain drugs or how drugs alter the brain to foster

compulsive drug abuse (NIDA, 2011; Pinel, 2011).

The purpose of this paper is to decrease the above gap by

providing scientific information about the disease of drug

addiction as it applies to a specific drug: marijuana, one of the

most commonly-abused and misunderstood drugs in the United States

(NIDA, 2011). Although marijuana is also one of the most popular

illegal drugs, people continue to form their opinions and

repertoires of understanding and knowledge on the myths and

misconceptions of the past. How is marijuana abused? Is

DRUG ABUSE 5

marijuana addictive? What treatment options are available? What

are the current trends in research on marijuana? This paper

answers these questions and clarifies the current understanding

of marijuana by discussing how marijuana is abused (i.e.,

chemical composition, how it affects the brain and its addictive

potential), its additional adverse effects on mental and physical

health, current treatment options, and current trends in its use

and addiction research.

Marijuana Abuse

Defining Marijuana. Marijuana is the name commonly given to

the mix of dried and shredded leaves, stems, seeds, and flowers

of the common hemp plant, Cannabis sativa (Pinel, 2011). Most people

report experiencing its pungent and distinctive odor of sweet and

sour smells throughout an increasing number of public and private

facilities (NIDA, 2011). The usual modes of consuming marijuana

are through: 1) smoking the leaves in a joint (a marijuana

cigarette) or pipe; or 2) ingesting them orally (i.e., brewed as tea

or baked in an oil-rich substrate [i.e., butter, chocolate

brownie, cookie, or cupcake] to promote absorption from the

gastrointestinal tract) (Pinel, 2011). Street names for marijuana

DRUG ABUSE 6

include pot, ganga, weed, Alice B. Tokely Brownies, Mary Jane, grass, 420, joints,

blunts (cigars that have been emptied of tobacco and refilled with

a mixture of marijuana and tobacco), or chronic (NIDA, 2011; Pinel,

2011).

Behavioral Effects. Although the marijuana plant contains

several hundred compounds, the psychoactive effects of marijuana

can be attributed to over 80 cannabinoids (active chemicals), most

of which can be found in the sticky resin coating the plant’s

leaves and flowers (Pinel, 2011; Smith et al., 2010). While most

of the psychoactive effects are attributable to a single

cannabinoid called THC (delta-9-tetrahydrocannabinol), the

resin’s psychoactive effects can also be enhanced by extracting

and drying them to make hashish (a dark corklike material) or hash

oil (an extremely potent product produced by further processing

hashish) (Pinel, 2011). Although the effects of a typical social

dose of marijuana tend to be subtle, high doses of marijuana have

been shown to impair psychological functions through short-term

memory impairments, distorted perceptions, slowed reaction time,

altered judgment and decision-making, difficulty thinking and

solving problems involving multiple steps to reach a specific

DRUG ABUSE 7

goal, and impairing communication skills (i.e., slurred speech,

short attention span) (NIDA, 2011; Pinel, 2011). Common effects

of marijuana abuse also include euphoria, calmness, emotional

intensification, sensory and time distortion, feelings of

paranoia, impaired coordination, and motor impairment (NIDA,

2011; Pinel, 2011).

Effects on Brain Mechanisms. Since the early 1990s, research

on THC has drastically changed the understanding of how marijuana

acts on the brain to produce its effects (NIDA, 2011; Pinel,

2011). Research has shown that when a person smokes marijuana,

THC immediately passes through the lungs into the bloodstream,

which carries it to the brain and other organs of the body (NIDA,

2011). In the brain, THC binds to specific sites called

cannabinoid receptors (CB1, the most prevalent G-protein-linked

receptor in the brain, and CB2, which is found in the brain stem

and in the cells of the immune system), starting a cellular

chain-reaction that ultimately produces the “high” that most

marijuana smokers experience and chase (Filbey et al., 2010;

Gómez-Ruiz et al., 2007; NIDA, 2011; Pinel, 2011). While some

areas of the brain have many cannabinoid receptors and others

DRUG ABUSE 8

have few or none, the highest density of receptors is found in

the frontal regions of the cerebral cortex and in the

hippocampus; areas responsible for executive functioning

processes such as decision making, planning, problem solving,

focused attention, response inhibition, cognitive flexibility,

working memory, several types of memory, concentrating, sensory

and time perception, visuospatial working memory, and coordinated

movement (NIDA, 2011; Smith et al., 2010). Understanding why

these THC receptors exist in the human brain has been greatly

enhanced by the recent discovery of a class of endogenous

cannabinoid neurotransmitters called endocannabinoids and the

isolation and characterization of the first endocannabinoid

neurotransmitter, anandamide (meaning “internal bliss”) (Gómez-

Ruiz et al., 2007; Pinel, 2011).

One study (Smith, Longo, Fried, Hogan & Cameron, 2010) used

functional magnetic resonance imaging (fMRI) to investigate the

effects of marijuana use on visuospatial working memory, the process

involved in the storage and manipulation of visuospatial

information for a short amount of time, followed by retrieval

(Smith et al, 2010). Participants were 19-21-year- old members of

DRUG ABUSE 9

the Ottawa Prenatal Prospective Study, a longitudinal study that

collected a unique body of information on participants from

infancy to young adulthood including prenatal drug history,

detailed cognitive/behavioral performance, and current and past

drug usage (Smith et al., 2010). Ten marijuana users (6 males, 4

females, mean age 20) and 14 nonusing controls (9 males, 5

females, mean age 20) were imaged for regular use of marijuana

use, which was defined as >1 joint/week (Smith et al., 2010).

Participants reported an average of 11.48 joints per week (range:

2 – 37.5 joints/week) on a regular basis for an average of 4.55

years (Smith et al., 2010). Prior to imaging, participants from

both groups previously completed a comprehensive psychological

battery including, the Wechsler Adult Intelligence Scale-III

(Wechsler 1997), the NEO Personality Inventory (Costa and McCrae

1989), the Computerized Diagnostic Interview Schedule for

Children, and a self-report drug questionnaire, which requested

information on current and past marijuana use, as well as other

drug use (Smith et al., 2010). The 10 marijuana users and 14

nonusing controls then performed a visuospatial 2-back task while

fMRI blood oxygen level-dependent response was examined (Smith et

DRUG ABUSE 10

al., 2010). Findings indicated that despite similar tasks

performance, marijuana users had significantly greater activation

in the inferior and middle frontal gyri, regions of the brain

normally associated with visuospatial working memory (Smith et

al., 2010). In addition, marijuana users had greater activation

in the right superior temporal gyrus, a region of the bran not

usually associated with visuospatial working memory tasks (Smith

et al., 2010).

Addiction Potential. Research shows marijuana’s addiction

potential to be low, with most people only using occasionally,

only about 10% using daily, and most people trying it in their

teens and curtailing use by the 30s or 40s (Pinel, 2011). Long-

term, regular marijuana abuse can lead to compulsive drug-seeking

and continued use despite the known harmful effects upon family,

school, work, and recreational functioning; both signs of

addiction (NIDA, 2011). Research estimates suggest a 9% addiction

rate among users, with an increase to 17% among those who start

young, and an increase to 25-30% among daily users (NIDA, 2011).

Tolerance to marijuana develops with sustained use, with long-

term abusers who are trying to quit reporting obvious withdrawal

DRUG ABUSE 11

symptoms (i.e., nausea, vomiting, sweating, diarrhea, sweating,

chills, irritability, sleeplessness, decreased appetite, tremors,

anxiety, and drug craving) beginning within 1 day following

cessation, peaking at 2-3 days, and subsiding within 1 or 2 weeks

(NIDA, 2011; Pinel, 2011). It must be noted, however, that these

symptoms are rare, except in contrived laboratory situations in

which massive oral doses are administered (Pinel, 2011).

Effects on Mental and Physical Health

Marijuana and Mental Health. A number of studies have shown

a correlation between chronic or heavy marijuana use and

increased rates of anxiety, depression, and schizophrenia (NIDA,

2011; Pinel, 2011). Some of these studies have also linked early

marijuana use to chronic or addictive problems later on (NIDA,

2011). These correlations have erroneously led many to conclude

that marijuana causes anxiety, depression, or schizophrenia or

that early marijuana use causes chronic use or addiction (Pinel,

2011). However, correlational evidence does not show causation;

it only demonstrates that a relationship exists between marijuana

and the increased rates of these mental problems (Pinel, 2011).

DRUG ABUSE 12

While chronic use of marijuana may not have been caused by

early use of the drug, chronic marijuana use in a very young

person may be a marker of risk for mental illnesses (including

addiction) stemming from genetic or environmental vulnerabilities

(i.e., early exposure to stress or violence) NIDA, 2011). One

study (Moore et al., 2007) linked high doses of marijuana with

acute psychotic reactions and with triggering the onset or

relapse of schizophrenia in vulnerable individuals. Once again,

however, this study shows correlation, not causation; an

observation that demonstrates that more research is required to

understand the causal factors involved in these correlations.

Effects on Physical Health. In addition to being linked to

anxiety, depression, and schizophrenia, marijuana adversely

affects the heart, lungs, and daily life. Research shows, for

example, that because marijuana increases the heart rate by 20 to

100% within the first hour after smoking, marijuana users

(especially older users or those with cardiac vulnerabilities)

have a 4.8-fold increased risk of palpitations, arrhythmias, and

heart attack within that same time period (NIDA, 2011). Studies

also show that marijuana contains 50 to 70% more carcinogenic

DRUG ABUSE 13

hydrocarbons than tobacco smoke (Lee & Hancox, 2011; NIDA, 2011).

To date, only two health hazards have been documented as being

caused by long-term, regular marijuana use: 1) the 10% of

marijuana smokers who smoke it regularly for long periods tend to

develop the same respiratory problems as tobacco smokers (i.e.,

cough, phlegm production, bronchitis, asthma, frequent acute

chest illness, and a heightened risk of lung infection; and 2)

because marijuana produces tachycardia, single large doses can

trigger heart attack in vulnerable individuals with a history of

previous heart attacks (Lee & Hancox, 2011; Pinel, 2011).

Furthermore, research demonstrates that heavy marijuana use

affects daily life by impairing several quality-of-life measures

(i.e., physical and mental health, cognitive abilities, social

life, and career status) and work measures (i.e., absences,

tardiness, accidents, workers’ compensation claims, and job

turnover) (NIDA, 2011).

Treatment Options

Although no medications are currently available, current

treatment options for marijuana abuse, dependence, or addiction

include behavioral interventions, cognitive-behavioral therapy,

DRUG ABUSE 14

and motivational incentives, such as providing vouchers for goods

or services to patients who remain abstinent (NIDA, 2011). The

most current treatment data on marijuana indicates that those in

treatment for primary marijuana abuse comprised 17% (322,000; 74%

male, 49% White, 30% between 12 and 17 years old) of those

admitted to U.S. treatment facilities in 2008, with 56% of those

in treatment for primary marijuana abuse having begun use by age

14 (NID, 2011).

Current Trends

Marijuana Abuse in the United States. As the most widespread

illicit drug used in the U.S. in 2010, more than 29 million

Americans (11.5%) aged 12 or older reported abusing marijuana in

2009; a significant increase over rates reported each year

between 2002 and 2008 (NIDA, 2011). According to NIDA-funded

Monitoring the Future Study of marijuana use among 8th, 10th, and 12th

graders, the decline in marijuana use that began in the mid-

1990’s is now demonstrated by past month usage of 8.0% in 8th

graders, 16.7% in 10th graders, and 21.4% in 12th graders, or 1

in 5 seniors (NIDA, 2011). Not surprisingly, marijuana use now

exceeds tobacco in reported past month use among 12th graders and

DRUG ABUSE 15

there is an increased rate of daily marijuana use reported in all

three grades, with 12th graders showing a 6.1% prevalence rate

for daily marijuana use, the highest reported since the early

1980's (NIDA, 2011).

Current Trends in Research. Current trends in marijuana

research have focused on its potential medicinal or therapeutic

properties (NIDA, 2011; Pinel, 2011). THC has demonstrated

remarkable potential for suppressing nausea and vomiting in

cancer patients, stimulating the appetite of AIDS patients,

blocking seizures, dilating bronchioles of asthmatics, decreasing

ocular pressure and the severity of glaucoma, and reducing

anxiety, some kinds of pain, and the symptoms of multiple

sclerosis (NIDA, 2011; Pinel, 2011). Cannabis-based medications

include synthetic compounds such as dronabinol (Marinol®), nabilone

(Cesamet®), and Sativex®, a mouth spray formulated to relieve

cancer-associated pain, spasticity, neuropathy, and the

neuropathic pain in multiple sclerosis (Kavia et al., 2010; NIDA,

2011). While dronabinol and nabilone have been approved by the

U.S. Federal Drug Administration (FDA), Sativex® has only

DRUG ABUSE 16

recently been approved in Canada for the relief of neuropathic

pain in MS (Wright, 2007).

One study (Wright, 2007) reviewed available clinical data to

examine the therapeutic potential of marijuana in neuropathic

pain, in movement disorders, and several other areas of

neurotherapeutics (Wright, 2007). The review’s aim was to discuss

the clinical evidence investigating the use of medicines derived,

directly or indirectly, from plant cannabinoids with special

reference to neurological disorders (Wright, 2007). Published

studies suggested that the oral administration of marijuana may

not be the preferred route of administration and that plant

extracts (i.e., Sativex®) show greater efficacy than synthetic

compounds (Wright, 2007).

According to Wright (2007), there are two cannabinoids

present in great quantities in marijuana plant extracts; THC and

CBD (cannabidiol) (Wright, 2007). CBD has been shown to have

antipsychotic in animal models, to show antipsychotic efficacy in

humans, to reduce THC-induced anxiety, to modulate THC-induced

postsleep cognitive impairment, and to have anxiolytic effects,

which may be mediated by effects on the hypothalamic-pituitary-

DRUG ABUSE 17

adrenal axis (Wright, 2007). As a whole, these findings present

good evidence for the meaningful therapeutic effect of marijuana,

especially with equal proportions of CBD and THC administered by

the sublingual route, as in Sativex® (Wright, 2007).

Concluding Discussion

Current issues in addiction research suggest that marijuana

addiction is psychologically-complex, that it is a disturbance of

decision making, that it is not limited to drugs, and that it

involves many transmitters (Pinel, 2011). This is evidenced by

the fact that addiction is currently defined as a chronic

relapsing brain disease expressed in the form of compulsive

behaviors (National Institute of Drug Abuse [NIDA], 2011). With

over 29 million drug users in 2010 (11.5%), marijuana is one of

the most commonly-abused and popular illicit drugs in the United

States. Yet, its addiction potential is low (10%) and its

withdrawal symptoms are rare, short-term, and mild. Why is this?

Is it because marijuana is not an addictive drug? The current

issues in addiction research suggest that the addiction

mistakenly attributed to marijuana is psychologically-complex,

DRUG ABUSE 18

involves many transmitters, and is not limited to the drug, but

rather to the reward circuits of the brain (Pinel, 2011).

Although it was once thought that marijuana causes brain

damage, almost all efforts to document brain damage from

marijuana use have proven to be negative and difficult to

directly-document; mostly because the effects of marijuana are

subtle, difficult to measure, and greatly influenced by the

social situation (Pinel, 2011). Scientists now know that, like

all addictions, there are three factors that trigger relapse in

abstinent marijuana users: priming doses of the drug, drug

associated cues, and stress; the prefrontal cortex mediates

priming-induced relapse, the amygdala mediates conditional cue-

induced relapse, and the hypothalamus mediates stress-induced

(Pinel, 2011). What this demonstrates is that the very areas that

are affected by marijuana use are also the areas implicated in

triggering relapse in marijuana users who are trying to quit.

Users attempting to quit should avoid stressful social

situations, as well as the priming doses and cues (i.e., one

‘hit’, ‘contact high’, marijuana’s odor, friends, parties)

associated with marijuana use and abuse. This suggests that

DRUG ABUSE 19

additional research is required to determine the causal factors

involved in marijuana’s correlations and that the therapeutic

role of cannabinoids should be the focus of research for many

years to come.

DRUG ABUSE 20

References

Filbey, F., Schacht, J., Myers, U., Chavez, R., & Hutchison, K.

(2010). Individual and additive effects of the CNR1 and FAAH

genes on brain response to marijuana cues.

Neuropsychopharmacology, 35(4), 967-75. Retrieved from

ProQuest Health and Medical Complete. (Document ID:

1958614611).

Gómez-Ruiz, M., Hernández, M., de Miguel, R., & Ramos, J. (2007).

An overview on the biochemistry of the cannabinoid system.

Molecular Neurobiology, 36(1), 3-14. Retrieved from ProQuest

Health and Medical Complete. (Document ID: 1940235531).

Kavia, R., De Ridder, D., Constantinescu, C., Stott, C., &

Fowler, C. (2010). Randomized controlled trial of Sativex to

treat detrusor overactivity in multiple sclerosis. Multiple

Sclerosis, 16(11), 1349-59. Retrieved from ProQuest Health

and Medical Complete. (Document ID: 2178085631).

DRUG ABUSE 21

Lee, M., & Hancox, R. (2011). Effects of smoking cannabis on lung

function. Expert Review of Respiratory Medicine, 5(4), 537-547.

Retrieved from ProQuest Health and Medical Complete.

(Document ID: 2440050591).

Moore, T. H., Zammit, S., Lingford-Hughes, A., et al. (2007).

Cannibis use and risk of psychotic or affective mental

health outcomes: A systemic review. Lancet, 370(9584), 319-

328.

National Institute on Drug Abuse (NIDA). (2011). Marijuana.

Retrieved from

http://www.drugabuse.gov/DrugPages/Marijuana.html

Pinel, J. (2011). Biopsychology (8th ed.). Boston: Allyn & Bacon.

Smith, A., Longo, C., Fried, P., Hogan, M., & Cameron, I. (2010).

Effects of marijuana on visuospatial working memory: an fMRI

study in young adults. Psychopharmacology, 210(3), 429-38.

Retrieved from ProQuest Health and Medical Complete.

(Document ID: 2038749811).

Wright, S. (2007). Cannabinoid-based medicines for neurological

disorders--Clinical evidence. Molecular Neurobiology, 36(1),

DRUG ABUSE 22

129-36. Retrieved from ProQuest Health and Medical

Complete. (Document ID: 1940235581).