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B4: 3 Cannabis HO2
GP Drug & Alcohol
Supplement No.10
June 1998
Cannabis Dependence and Treatment
Helen Astolfi, Louise Leonard & Deborah Morris
Introduction
Cannabis is the most commonly used illicit
drug in Australia, and in Western society in
general1. There has been a steady increase
in cannabis use in Australia since the early
1970s, however, rates of cannabis use are
not as high as tobacco and alcohol use1.
Mostly cannabis is used intermittently, either
experimenting with it once or twice or using
it occasionally for recreational purposes.
The Drug
Prevalence of Cannabis Use
Approximately one third of Australians over
14 years of age have ever used cannabis1.
The prevalence of ever having used
cannabis is strongly related to gender and
age. Men are more likely to have used
cannabis than women, and adults over the
age of 40 are much less likely to have used
than younger adults.
In the past, cannabis has erroneously been
classified as a narcotic, a sedative and most
recently as an hallucinogen. Cannabis does
possess some hallucinogenic properties,
together with disinhibiting and sedative
effects.
Rates of cannabis use are highest among
people aged 20-24 years, with over 80% of
males and 60% of females from this group
having tried cannabis. Use of cannabis
usually declines after early adulthood, with
only a minority continuing to use regularly.
Even in the case of the minority who use
daily, the majority of these people cease
their use of cannabis by their mid to late
20s1. It is uncommon for people who use
cannabis to progress on to develop
problems with other illicit drugs.
Cannabis is the generic name given to a
variety of preparations derived from the
herbaceous plant Cannabis sativa. Slang
terms for cannabis include marijuana, grass,
dope, pot, weed and mull.
The cannabis plant produces a sticky resin,
which covers the flowering tops and upper
leaves. The resin contains the psychoactive
ingredient delta-9-tetrahydrocannabinol
(THC).
THC concentration varies with the forms in
which cannabis is prepared for use. The
most common preparations are marijuana,
hashish and hash oil. Marijuana is prepared
from the dried flowering tops (‘heads’) and
leaves of the plant. The concentration of
THC is determined by the growing
conditions, genetic nature and balance of
plant matter. The flowering tops or ‘heads’
possess the highest THC concentration (1025%), with the concentration decreasing
through the upper leaves, lower leaves,
stems (5-10%) and seeds2.
Hashish or hash is made up of dried
cannabis resin and compressed flowers and
is generally sold in hard chunks or cubes.
The THC concentration in hashish can be as
high as 20-40%. Hash oil is extracted from
hashish using an organic solvent and is a
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highly potent viscous substance. THC
concentration in hash oil has been found to
be as high as 70%.
 the social environment and mood of the
user
The most common form of administration is
by inhalation (smoking). Marijuana can be
hand rolled into a ‘joint’ with tobacco and
smoked, although it is most often inhaled
through a water pipe known as a ‘bong’. A
bong is a popular implement for smoking
because there is little loss of the drug
through sidestream smoke and the water
cools down the hot smoke.
Acute Cognitive Effects
Pharmacology of Cannabis
The main effects of cannabis are on
cognitive functioning. These effects are
exerted through cannabinoid receptors that
are located in both the hippocampus and
cortex of the brain. High densities of
cannabinoid receptors also appear in the
basal ganglia and cerebellum; this is
consistent with the finding that cannabinoids
interfere with coordination2.
THC is lipid soluble and is stored readily in
fatty tissues. As a consequence, traces of
cannabinoids can be found slowly escaping
from fat tissues, and thus be present in
urine, up to two to three months after use of
cannabis, therefore, a positive urine test for
cannabis is not an absolute indication of
recent cannabis use, although higher urinary
cannabinoid levels will provide an indication
of more recent use2.
The Acute Effects of Cannabis Use
The use of cannabis can result in a ‘high’ or
altered state of consciousness. This state is
characterised by emotional changes such as
mild euphoria, perceptual changes, and
heightened sensory experiences, e.g.
listening to music, eating, watching films,
etc.
The effects of cannabis are highly variable,
and depend upon the following2:
 the dose
 administration route
 prior experience with the drug
 concurrent drug use
 the user’s expectations of the effects of
the drug
Cannabis use can affect cognition, causing
short term memory impairment.
Acute Psychiatric Effects
Some individuals have reported unpleasant
effects from cannabis use ranging from
anxiety to panic attacks, depressed mood,
and a fear of ‘going crazy’. However, these
effects
are
mostly
found
in
the
inexperienced user, and can usually be
managed with reassurance and support.
Psychotic symptoms such as delusions and
hallucinations can occur in individuals using
very high doses of THC, although this is a
rare occurrence. These symptoms may also
be experienced at lower doses by people
who have a vulnerability to psychosis3.
Acute Physical Effects
The most immediate effect of cannabis use
is an increase in heart rate which can last up
to three hours. In the young, healthy user,
cardiovascular changes are generally
clinically insignificant. However, cannabis
may adversely affect patients with ischaemic
heart
disease,
hypertension,
and
cerebrovascular disease. In the susceptible
patient,
cannabis
acts
to
increase
catecholamine production which can cause
arrhythmias, and increase heart rate
resulting in angina2. Postural hypotension
may also be an acute effect of cannabis
use.
Acute Psychomotor Effects
Coordination and reaction time are impaired
during intoxication with cannabis4. Of
particular concern is the impact of cannabis
intoxication on driving ability. Some studies
suggest an increased risk of motor vehicle
accidents among individuals who drive when
intoxicated by cannabis. This increased risk
may be due to the combined use of alcohol
and cannabis2. Therefore, it is pragmatic to
advise cannabis users not to drive a motor
vehicle while under the influence of
cannabis.
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The Effects of Chronic Cannabis Use on
Health
Evidence suggests that cannabis smoke is
mutagenic and shares many of the same
carcinogens as cigarette smoke2.
The major cancers arising from cannabis
use are those involving the respiratory tract
and the aerodigestive tract. In addition, there
is evidence that habitual marijuana use
causes airway abnormalities affecting mainly
the large airways; tobacco use alone affects
predominantly the peripheral airways and
alveoli2. Research suggests that long-term
cannabis use may cause chronic bronchitis2.
There is a possibility that chronic, heavy
cannabis smoking may have subtle effects
on the cardiovascular system2.
The Psychological
Cannabis Use
Effects
of
Chronic
A major concern regarding the psychological
effects of cannabis use is the impact it has
on motivation, particularly in adolescence.
Chronic use interferes with developmental
tasks, such as educational achievement,
separation from parents, forming peer
relationships, and making important life
choices5.
Reproductive Effects
Studies carried out on male animals have
shown that cannabis use reduces plasma
testosterone
levels,
retards
sperm
maturation, reduces sperm count and sperm
motility, and increases the rate of abnormal
sperm production2.
Studies on human females have conflicting
results. In female animals, studies have
shown that chronic cannabis use interferes
with ovulation and probably has an inhibitory
effect on the female reproductive system2.
Pregnancy
Pregnant women who smoke cannabis are
at risk of a shorter gestation period and
giving birth to low weight babies6. Women
May 1998
who smoke cannabis at the time of
conception or while pregnant may increase
the risk of birth defects, although research is
inconclusive2.
Women
should
be
encouraged to abstain from cannabis when
trying to conceive and during pregnancy.
Cannabis Dependence
For much of the 1960s and 1970s there was
a widespread belief that cannabis was not a
drug of dependence1. This belief was due to
an apparent absence of tolerance to the
effects of cannabis or of a withdrawal
syndrome, particularly when compared to
that of alcohol and opioid dependence.
Views on the nature of dependence
changed in the late 1970s and early 1980s
when the definition of drug dependence,
embodied in the alcohol dependence
syndrome7, was extended to all psychoactive
drugs8.
The importance of tolerance and withdrawal
symptoms was reduced in favour of a
greater emphasis upon continued use of a
drug in the face of its adverse effects1.
A diagnosis of cannabis dependence2 (DSMIII-R) is made if any three of the following
criteria have been present for one month or
longer:
1. cannabis is often taken in larger amounts
or over a longer period than the person
intended
2. there is a persistent desire or one or
more unsuccessful efforts to cut down or
control cannabis use
3. a great deal of time is spent in activities
necessary to get cannabis, e.g. theft,
taking cannabis, or recovering from its
effects
4. frequent intoxication or withdrawal
symptoms when expected to fulfil major
role obligations at work, school or home,
or when cannabis is physically hazardous
5. important
social
occupational
or
recreational activities given up or reduced
because of cannabis use
6. continued
cannabis
use
despite
knowledge of having a persistent or
recurrent social psychological or physical
problem that is caused or exacerbated by
the use of cannabis
7. marked tolerance
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Withdrawal Symptoms
Evidence suggests that abrupt cessation of
chronic, high doses of THC can produce a
withdrawal syndrome that persists for
between four days and a week. The
cannabis withdrawal syndrome is not
medically dangerous.
The most common withdrawal symptoms
caused by stopping regular use of cannabis
include9:
 anxiety
 irritability
 perspiration
 sleep disturbances
 moodiness
 anorexia
Uncommon withdrawal symptoms include:
 tremors
 nausea/vomiting
 occasional diarrhoea
 excessive salivation
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been shown to give a more accurate picture
of consumption.
Identify Problems Related to Drug Use
 dependence
 withdrawal symptoms
 other medical symptoms
 psychological & psychiatric symptoms
 relationship problems
 social problems
 legal problems
 problems at work
 financial problems
Mental State Assessment
Conduct a focused mental state assessment
where psychiatric symptoms are evident.
Physical Examination
A brief physical examination focusing on
medical complications of cannabis use
should also be conducted.
Treatment Matching
Management of Patients with Cannabis
Related Problems
Assessment
The assessment of a patient who is using
cannabis includes:
Taking a Drug Use History
This should include a history of amount,
frequency, duration, route of administration
and pattern of use. It should also identify
when the patient last used cannabis. A
retrospective time line history of cannabis
use, is the most accurate way to obtain a
drug use history.
A retrospective timeline history is taken by
starting with “When did you last use
cannabis?” Ascertain how much was
consumed at that time. Then enquire back
through that day “What about during the
day?” Tie cannabis consumption to activities
“What were you doing during the day?” then,
for example, “How much did you use when
you went to your friend’s house?”
Consumption through each day is enquired
about for the last week. The patient is then
asked if this was a typical week’s use for
them. This method of taking a history has
The three main considerations in matching a
patient to treatment of cannabis related
problems are:
 what the patient wants
 the severity of the patient’s cannabisrelated problems
 the safety of the patient, i.e. risk of
suicide or harm to others from psychotic
symptoms or depressive symptoms.
Another key issue in assessing what
strategy is used for patients who are
cannabis dependent is their readiness to
quit. A useful model in assessing a patient’s
motivation is the ‘Stages of Change Model’10
(Figure 1).
This model provides a simple method of
questioning to determine the ‘stage of
change’ of the patient. The model involves
four stages and indicates whether the
patient:
 is not ready (pre-contemplation stage)
 is unsure (contemplation stage)
 is ready (action stage)
 has quit, but is at risk of relapse
(maintenance stage).
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users should be aware of the major
including:
 increased risk of being involved
motor vehicle accident if driving
intoxicated
 risk to the respiratory system
 increased risk of infertility and
problems
 risk of dependence with daily use
Relapse
Maintenance
Action
Pre
contemplation
Contemplation
Figure 1 (adapted
DiClemente10)
from
May 1998
Prochaska
&
This process is active, in that the patient can
be assisted through each of the stages in
order to achieve the patient’s desired goal.
Treatment Approaches
There is a widespread view that cannabis
dependence does not require treatment
because the withdrawal syndrome is so mild
and most users can cease their use without
assistance. There are, however, a
substantial number of cannabis users who
seek professional assistance because, as
for those who are nicotine dependent, past
attempts to cease have failed.
For these people, treatment approaches
include:
 brief advice
 assisted cessation of cannabis use
together with education about its acute
and chronic effects
 assistance with withdrawal symptoms
 skills training in resisting social cues for
use
 self help groups
 relapse prevention groups
 outpatient counselling
Further research is needed to evaluate the
effectiveness of these treatment methods.
However, enough is known to advocate less
intensive outpatient treatment options over
expensive inpatient treatment.
Brief advice
Abstinence is the simplest advice for those
wishing to avoid the probable adverse health
effects of cannabis, particularly those whose
health is already compromised. Current
risks
in a
while
birth
Strategies for quitting
There are a number of strategies11 that may
assist with quitting, particularly in the initial
stages. All of the following strategies may
help at some stage or another:
 set a date and stick to it
 replace cannabis with new activities and
interests
 avoid situations where there is a
likelihood of getting stoned
 it is not necessary to go it alone; ask a
friend for support
 say to others “I don’t get stoned
anymore!”
Lifestyle changes
Quitting cannabis is like learning a new skill;
the more effort one puts in, the more skilled
one becomes. Success in remaining
abstinent is often due to changes in lifestyle,
and may include:
 telling friends “I don’t smoke anymore”
 changing diet to include healthier foods
 increasing exercise
 avoiding stressful situations, or learning
to manage stress in ways other than
getting stoned
 meeting new people
 understanding feelings of anger and
frustration
 avoiding situations that are likely to cause
relapse, e.g. avoid parties where smoking
is likely, at least for a few months
 escaping from situations where other
people are smoking or are about to
smoke
 a reminder as to why cannabis was given
up
 noticing how many people don’t smoke
 having someone listen about their
lifestyle change
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GP Drug & Alcohol Supplement No. 10
 removing all the things from their home
that remind the patient of smoking
cannabis
 not replacing cannabis with alcohol and
cigarettes
Assistance with withdrawal symptoms
The vast majority of patients do not suffer
distressing cannabis withdrawal symptoms,
and do not require medication during
withdrawal. However, a small number of
patients may require help to negotiate the
cannabis withdrawal symptoms. If agitation,
sleep
disturbance,
restlessness
and
irritability are major problems for a patient, a
benzodiazepine (such as diazepam) may be
given for up to four days at a dose of 5 mg
tds. Benzodiazepines should not be
continued beyond four days in these
patients. These patients will require support
and counselling throughout the four days to
a week of withdrawal symptoms. A home
detoxification service can assist in the
management of these patients during the
withdrawal syndrome.
Relapse prevention
Reverting to old habits is one reason people
fail in their attempts to quit. Preventing
relapse is an important aspect of treatment
and assists the patient in maintaining their
behaviour change. The following techniques
can be taught to the patient in the early
stages of abstinence when there is a high
risk of using cannabis again:
Delay
Delaying the desire to smoke will help to
reduce feelings of anxiety and panic. Instead
of saying “I will never smoke again”,
postpone having a smoke for the next
minute, hour or day. When this time is up
postpone smoking again.
May 1998
Distract
Distract one’s mind from smoking when the
urge arises. This could include:
 meditation
 bushwalking
 surfing
 interaction with a friend
 deep breathing
 positive imagery
Avoid
Avoid people and places that trigger the
desire to ‘get stoned’, particularly in the first
few weeks from the quit date. For example,
if going to a party where people will be
smoking it may be best to avoid parties for
the first couple of months from the quit date.
Escape
If all the above tactics fail, escaping from the
high risk environment will lower the urge to
smoke. Taking a break from the situation
where other people are smoking or about to
smoke, or stepping outside for a brief walk
can also help in the patient’s pursuit to
cease cannabis use.
Lapses
Sometimes the urge to ‘get stoned’ can be
overwhelming. If patients do relapse it is
important they do not think of themselves as
failures. Think of it as a lapse in
concentration and encourage patients to
renew their commitment to quit. Remaining
positive encourages patients to be confident
that they are capable of achieving their
goals.
General Practitioners who require further
information regarding the management of
cannabis dependence can contact the Drug and
Alcohol Local Consultancy Service on
0413 276 177.
The Local Consultancy Service is for General
Practitioners only. Patients can contact the
Central Coast Alcohol and Other Drug Service on
4393 4880.
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GP Drug & Alcohol Supplement No. 10
May 1998
References
1. Donnelly, N. & Hall, W. (Eds) 1994. Patterns of cannabis use in Australia. Monograph Series No. 27. Australian
Government Publishing Service: Canberra.
2. Hall, W., Solowij, N. & Lemon, J. (Eds) 1994. The health and psychological consequences of cannabis use.
Monograph Series No. 25. Australian Government Publishing Service: Canberra.
3. Thomas, H. 1993. Psychiatric symptoms in cannabis users. British Journal of Psychiatry 163: 141-149.
4. Jaffe, J.H. 1985. Drug addiction and drug abuse. In A.G. Gilman, L.S. Goodman & F. Murad (Eds), The
pharmacological basis of therapeutics. 7th edition. Macmillan: USA.
5. Baumrind, D. & Moselle, K.A. 1985. A developmental perspective on adolescent drug abuse. Advances in Alcohol
and Substance Abuse 5: 41-67.
6. Hatch, E.E. & Bracken, M.B. 1986. Effect of marijuana use in pregnancy on fetal growth. American Journal of
Epidemiology 124: 986-993.
7. Edwards, G. & Gross, M.M. 1976. Alcohol dependence: provisional description of a clinical syndrome. British
Medical Journal 1: 1058-1061.
8. Edwards, G., Arif, A. & Hodgson, R. 1981. Nomenclature and classification of drug- and alcohol-related problems: a
WHO memorandum. Bulletin of the World Health Organization 59: 225-242.
9. Grenyer, B., Solowij, N. & Peters, R. 1996. A guide to quitting marijuana. NDARC: Sydney.
10. Prochaska, J.O. & DiClemente, C.C. 1986. Toward a comprehensive model of change. In W.R. Miller & N.
Heather (Eds), Treating addictive behaviors: processes of change. Plenum Press: New York.
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