Risk behavior and addiction in adolescence
College 1
Cannabis use and the mental health of young people (wayne d. hall)
This paper critically reviews epidemiological evidence to answer the following questions about the
psychosocial consequences of adolescent cannabis use: Is there a cannabis dependence syndrome?
Is cannabis a ‘gateway drug’ to the use of heroin and cocaine? What role does cannabis use play in
educational underachievement? What role does cannabis use play in the precipitation and
exacerbation of psychosis?
Is there a cannabis dependence syndrome?
cannabis was not regarded as a drug of dependence because it did not seem to produce a withdrawal
syndrome but studies; and observational studies of regular users have described a cannabis
withdrawal syndrome that includes anxiety, insomnia, appetite disturbance and depression
The risk of developing dependence is approximately one in 10 for those who have ever used cannabis
and perhaps as high as one in two for daily users. The risk is higher for people with a history of poor
academic achievement, deviant behavior in childhood and adolescence, nonconformity and
rebelliousness, personal distress and maladjustment, poor parental relationships, and a parental
history of drug and alcohol problems. Only a minority of those who meet criteria for cannabis
dependence in community surveys report seeking treatment. But among the minority of dependent
users who do seek help after failing to quit unassisted, many report cognitive, mood and motivational
impairments that interfere with work performance. Cannabis dependent adolescents in substance
abuse treatment services also report withdrawal symptoms. Evaluations of psychological
interventions for cannabis dependence report abstinence rates of 20– 40% at the end of treatment,
with substantial rates of relapse thereafter. Nonetheless, treatment substantially reduces use and
problems among those who do not succeed in quitting, an outcome that is similar to that for
treatment for dependence on alcohol and other substances
Is cannabis a ‘gateway drug’ to the use of heroin and cocaine?
Surveys of adolescent drug use in the US and elsewhere over the past 30 years have consistently
shown the following relationships between cannabis use and the use of other illicit drugs, such as
heroin and cocaine.
Three explanations are often suggested of these patterns: (i) that users of cannabis are more likely to
use other illicit drugs because they obtain cannabis from the same black market and hence have
more opportunities to use other illicit drugs; (ii) that those who use cannabis at an early age are more
likely for other reasons to use other illicit drugs; and (iii) that the pharmacological effects of cannabis
increase an adolescent’s propensity to use other illicit drugs.
The association between regular cannabis use and the use of other illicit drugs could also arise from
the selective recruitment into early cannabis use of socially deviant young people who have a high
likelihood of using cocaine and heroin. The observed sequence of drug involvement, on this
hypothesis, would simply reflect the availability and societal disapproval of the different drugs, and
cannabis and heroin use would be common consequences of pre-existing propensities to use drugs.
The selective recruitment hypothesis has been tested in longitudinal studies by assessing whether
cannabis use predicts the use of heroin and cocaine after statistically controlling for differences
between cannabis users and non-users in personal characteristics that preceded their cannabis use.
,In one of the earliest such studies, found that the relationship between cannabis use and ‘harder’
illicit drug use was reduced but still persisted after statistically controlling for pre-existing adolescent
behaviors and attitudes, interpersonal factors and the age of initiation into drug use.
Twin studies suggest that the association between cannabis and other illicit drug use may be
explained by a shared genetic contribution to dependence on alcohol, cannabis, tobacco and other
drugs
(ze hebben het over de gateway pattern dat houdt dus in het patroon dat je eerst cannabis gebruikt
maar later ook andere soorten drugs als het goed is)
If cannabis use somehow causes the use of other illicit drugs then delaying adolescent cannabis use
should reduce the use of other illicit drugs. But no studies showed this. To show this effect would be
difficult, very large sample sized are needed to detect the small effects that delays in cannabis use
may have on the use of other drugs.
There is some biological plausibility for a causal relationship between cannabis and other types of
drug use. But the pattern remains controversial. Studies do not wholly explain the association. So the
exact nature of the relationship is vague. But the association between cannabis use and other types
of drugs use persists.
However, this relationship remains controversial because it's challenging to rule out the possibility
that it's driven by shared characteristics among individuals who use both cannabis and other drugs.
What role does cannabis use play in educational underachievement?
Educational Performance: Cannabis use is linked to poor educational attainment among school
children and youth. It's debated whether cannabis use impairs performance or if it's a consequence
of poor educational attainment (slechte school prestaties). Both cannabis use and poor educational
attainment are influenced by common factors, such as ADHD, externalizing disorders, or cognitive
impairment. Both hypotheses could be true, with poor school performance increasing the risk of
cannabis use, which then worsens performance. There may also be common risk factors.
What role does cannabis use play in the precipitation and exacerbation of psychosis?
Psychosis: Cannabis use and psychotic symptoms and disorders are associated. Hypotheses explaining
this association include the idea that cannabis use may precipitate schizophrenia, that it serves as
self-medication for schizophrenia, or that the association arises from confounding variables.
Swedish Conscript Study: A long-term study found a dose-response relationship between cannabis
use and the risk of schizophrenia. The relationship persisted even after statistical adjustments for
potential confounders. European Cohort Studies: Multiple European studies supported the link
between cannabis use and psychosis. They found dose-response relationships, and the relationship
remained significant after controlling for other drug use and potential confounders. New Zealand
Birth Cohorts: Studies in New Zealand also supported the association between cannabis use and
psychotic symptoms. Even after adjusting for potential confounders, the link remained significant.
Self-Medication Hypothesis: The idea that people with psychosis use cannabis to self-medicate was
not strongly supported by research. Studies found that early psychotic symptoms did not predict an
increased risk of cannabis use, and users did not report using cannabis to control symptoms.
, Different studies have used different ways of assessing cannabis use and psychotic symptoms; few
studies have assessed psychosis using diagnostic criteria, or attempted to distinguish between
schizophrenia and affective psychoses. Despite the heterogeneity of methods and definitions of
psychosis, there is reasonably consistent evidence from prospective studies that frequent cannabis
use predicts an increased risk of psychotic symptoms and psychosis that is not explained by potential
confounders such as other drug use. The relationship has also been stronger in people who have a
personal or family history of schizophrenia which one recent study suggests may be explained by an
interaction between a genetic vulnerability to psychosis and cannabis use.
Summary:
Adolescent cannabis users can become dependent on cannabis. The risk is lower than that for
alcohol, nicotine and opiates but 10% is not trivial and the risk is higher for young people who start at
a younger age. Young people who become dependent on cannabis are at increased risk of using other
illicit drugs, performing poorly at school and leaving early without completing qualifications, and
experiencing psychotic symptoms. It remains controversial which of these associations between
regular cannabis use and adverse outcomes are causal. The most controversial relationship is that
between the regular use of cannabis and the use of other illicit drugs where the choice is between a
common causal explanation (whether due to shared personal characteristics, shared environments or
shared genes or combinations thereof) and a causal explanation in terms of either drug markets or
the pharmacological effects of cannabis. The evidence for a causal relationship is stronger for
educational underachievement and the risk of psychotic symptoms. A number of longitudinal studies
have found that these relationships persist when controlling for plausible confounding variables and
both relationships are biologically plausible in that cannabis intoxication acutely impairs cognitive
function and increases psychotic symptoms, especially in people with a personal history of such
symptoms. Confidence in a causal relationship will increase as larger and better-controlled
longitudinal studies are reported on these relationships. These findings raise a major challenge for
health education of young people about the risks of cannabis use. Arguably, we have a moral
obligation to alert young people to these risks. The major challenge will be in finding effective ways of
communicating with young people about the most probable psychosocial harms of cannabis use
(dependence, educational underachievement and psychosis) given the continuing debate about the
causal interpretation of these risks and polarized community views about whether we should
continue to criminalize cannabis use.
