IUMSP Institut universitaire de médecine sociale et préventive, Lausanne Tell me what you smoke and I'll tell you where you'll end: tobacco, cannabis and

IUMSPInstitut universitaire de médecine sociale et préventive,

Lausanne

Tell me what you smokeand I'll tell you where you'll end:tobacco, cannabis and adolescents

Joan-Carles Suris, MD, PhD

Université de Lausanne, Switzerland


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Four youths…

Youth 1 Youth 2 Youth 3 Youth 4

Age 16 16 16 16

Tobacco No No Yes Yes

Cannabis No Yes No Yes

Which one are you the most worried about?

Which is the second one you are the most worried about?


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Outline Some epidemiological data Theories Tobacco and cannabis Ups and downs (controversies) Predictor factors Trajectories (TREE cohort)


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Some epidemiological data


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0 5 10 15 20 25

Italy

Malta

Greece

Switzerland

Spain

Israel

Portugal

USA

Girls Boys

Smoking at least once a week, 15 year-olds

Source: HBSC 2006


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0 5 10 15 20 25

Italy

Malta

Greece

Switzerland

Spain

Israel

Portugal

USA

Girls Boys

Cannabis in the last 30 days, 15 year-olds

Source: HBSC 2006


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0 5 10 15 20 25

Italy

Malta

Greece

Switzerland

Spain

Israel

Portugal

USA

Tobacco Cannabis

Girls: current cannabis/tobacco 15 year-olds

Source: HBSC 2006


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0 5 10 15 20 25

Italy

Malta

Greece

Switzerland

Spain

Israel

Portugal

USA

Tobacco Cannabis

Boys: current cannabis/tobacco, 15 year-olds

Source: HBSC 2006


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0

10

20

30

40

50

1994 1996 1998 2000 2002 2004 2006 2008

%

Tobacco M Tobacco F Cannabis M Cannabis F

Last 30 days, Spain, 14-18 year-olds


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Theories


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Gateway theory (Kandel, 1975)

No useTobacco and/or

AlcoholCannabis

Other illegal drugs

Reverse gateways (Patton et al., 2005)

No use Cannabis Tobacco


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Tobacco and cannabis


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21% of cannabis users declared never having smoked cigarettes

Cannabis-only adolescents showed better functioning than those who also used tobacco.

Compared with abstainers, they were more socially driven and did not seem to have psychosocial problems at a higher rate.


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Ontario Child Health Study (OCHS)

Tobacco only Cannabis only Tobacco & cannabis

Physical health - - - -

Life satisfaction - -

Personal income - - - - - -

Years of education - -

Depression - -

Georgiades & Boyle, J Child Psychology Psychiatry, 2007


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Pure joints are too strongPure joints do not burn correctlyIt is too expensive to smoke pure joints


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Evidence now indicates that

nicotine dependence and

persistent cigarette smoking

may be the main public health

consequences of cannabis useAgrawal et al., Drug & Alcohol Dependence, 2008


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Ups and downs (controversies)


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Is it just a ‘phase’?

In contrast to

users of tobacco and alcohol,

most cannabis users

quit using cannabis

relatively early in their adult lives.

Sidney S, BMJ, 2003


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Between the ages of 18 and 24

about three-quarters of the sample

did not use marijuana (47%)

or used it only infrequently (28%)

Schulenberg et al., J Drug Issues, 2005


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For many young people,

some or even frequent marijuana use

appears to be

developmentally limited

and not associated with difficulties

with the transition to adulthood



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The progression to

higher usage categories

during the follow-up period

is more frequent

than to lower categories

Perkonigg et al., Addiction, 1999


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While many young people moderate

their cannabis use patterns

during adolescence,

the impact of moderation on

later regular/dependent use may be limited,

particularly among adolescents

initially reporting regular cannabis use

Swift et al., Addiction, 2009


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Although the use of cannabis

is not harmless,

the current knowledge base

does not support the assertion

that it has any notable adverse

public health impact

in relation to mortality.Sidney S, BMJ, 2003


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Predictor factors


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The life-event effect

At age 23-24 years,

married respondents

and those who were parents

were overrepresented

in the Decreased and Abstain groups



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Early alcohol dependence

may be a selective risk factor,

discriminating those with

a long-term risk of chronic use

from those who stop using cannabis

after adolescence or early adulthood


Alcohol


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Youth who had

never tried cannabis at baseline

were found to be most likely to be classified

as non-users at follow-up (82%)

and regular users classified

with considerable use at baseline

are also likely

to remain in the same group (54%)


Prior use


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A dose-response effect

Overall the probability of stopping cannabis use decreases fairly consistently with

increased frequency of use at baseline.

This pattern seems to suggest a “dose-response” relationship: the higher the

baseline use, the higher the probability of continued and heavier use at follow-up



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Association between adolescent and young adult cannabis use

Weekly+ at age 24 Dependent at age 24

No use 0.21 0.16

Occasional use 1 1

Weekly use 2.2 2.8

Daily use 4.9 5.8

1-2 waves 1 1

3-6 waves 2.7 2.3

Late reported use 1 1

Early reported use 3.2 2.7



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Tobacco

It appears that

adolescent tobacco use

accounts for much of

the distal association between

adolescent cannabis use

and adult outcomes

Georgiades & Boyle, J Child Psychology Psychiatry, 2007


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Male gender,

regular cannabis use (weekly),

persistent antisocial behavior,

and persistent cigarette smoking

independently predicted

cannabis dependence

Coffey et al., Br J Psychiatry, 2003

Tobacco & Cannabis


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Simultaneous users

of tobacco and cannabis

are an

especially vulnerable population

Agrawal et al., Drug Alcohol Dependence, 2009

Tobacco & Cannabis


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Trajectories (TREE cohort)


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Methods Data were drawn from the TREE cohort (www.tree-ch.ch) A longitudinal study of a representative sample of Swiss

youth surveyed yearly from 2001 (T1, N=5528, mean age 16.7 years) to 2007 (T7, N=3979, mean age 22.7 years).

According to their use of tobacco and/or cannabis at T1 (N=1955), subjects were divided in 4 groups: Those using cannabis only (N=45, 2.3%) Those using tobacco only (N=518, 26.5%) Those using both substances (N=360, 18.4%) Those using neither (N=1032, 52.8%)


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Methods (2)

Outcome variables at T7 were: Smoking: No

Occasionally

Daily Cannabis use: No

Occasional (less than weekly) Regular (weekly or more)

We performed a multinomial logistic regression using the group neither as the reference category and controlling for age, gender and alcohol use at T1


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Results

Cannabis only at T1

(N=45)

Tobacco only at T1 (N=518)

Tobacco & Cannabis at T1 (N=560)

Occasional tobacco at T71,18

[0,54/2,60]3,91

[2,42/6,33]5,29

[2,50/11,18]

Daily tobacco at T71,88

[0,59/3,97]17,73

[11,24/27,96]16,37

[8,22/32,62]

Occasional cannabis at T74,57

[1,44/14,52]1,27

[0,49/3,28]4,62

[1,55/13,79]

Regular cannabis at T76,31

[1,74/22,82]1,76

[0,54/5,75]15,83

[4,57/54,84]

(Controlling for age, gender and alcohol use at T1)


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Results: Cannabis only at age 16

Cannabis only

49%

28%

16%

7% Cannabis only

Abstinent

Tobacco only

Tobacco & Cannabis

16 17 18 19 20 21 22Age


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Tobacco & Cannabis

Cannabis only

Abstinent

Tobacco only

Tobacco & Cannabis

Results: Tobacco & Cannabis at age 16

11%

44%

42%

4%

16 17 18 19 20 21 22Age


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Results: Tobacco only at age 16

Tobacco only

21%

66%

12%

Cannabis only

Abstinent

Tobacco only

Tobacco & Cannabis

16 17 18 19 20 21 22Age

1%


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Results: Abstinent at age 16

Abstinent 73%

23%

3%

1% Cannabis only

Abstinent

Tobacco only

Tobacco & Cannabis

16 17 18 19 20 21 22Age


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At age 16 they are already in a substance use trajectory

Occasional/recreational cannabis use can often be a phase, but…

The use of both substances is the one with worse outcomes

Between ages 16 and 22, it is more frequent to go from cannabis to tobacco than the other way around

[Some] take home messages


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Alcohol is an important predictor factor Life events are also an important predictor

factor (both ways) Having faith in the future is a protective

factor Age solves (almost!) everything

[Some] take home messages (2)


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Let’s return to our four youths…

Youth 1 Youth 2 Youth 3 Youth 4

Age 16 16 16 16

Tobacco No No Yes Yes

Cannabis No Yes No Yes

Which one are you the most worried about?

Has the second one you are the most worried about,

changed?


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“Can these findings be used to recommend a ‘safe’ level of adolescent cannabis use with regard to later

problematic use?

Although regular adolescent cannabis users appear to have an elevated long-term risk of problematic cannabis compared to their less regularly using

peers, occasional adolescent use per se clearly does not preclude the outcomes at age 24.

It would be irresponsible to promote such use as ‘safe’”



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IUMSP Institut universitaire de médecine sociale et préventive, Lausanne Tell me what you smoke and I'll tell you where you'll end: tobacco, cannabis and