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Nicotine Dependencein Young Smokers
J O’LoughlinTobacco and Health: From Cells to SocietyOctober 2014
Plan
Background
What is Nicotine Dependence?
ND measurement
Why this interest in ND in youth?
What’s next?
NDIT Study
Background Prevalence has declined but 14%
of grade 9-12 students smoked in the last 30 days (YSS 2013)
Age at first whole cigarette is 11.8 yrs
Daily smoking begins at age 16
75-80% of adolescents try, 1/5 will escalate
14% of those who try do so for the first time after high school (young adult onset)
Background Early smokers smoke more, longer, less likely
to quit
Smoking co-occurs with alcohol, illicit drugs, gambling
Young smokers at higher risk of premature death
Prevention programs not effective (little known about mechanisms of onset and progression)
Cessation in youth is a relatively new concept
Youth Smoking Differs From Adults More environmental constraints (home, school,
financial, legal, availability of cigarettes)
Sporadic, irregular smoking patterns
Share cigarettes with friends or just smoke a few puffs
ND symptoms experienced/reported differently by youth (unknown symptoms, different terminology)
No generally accepted measure to assess ND in youth
What is Nicotine Dependence?
DSM-V Tobacco Use Disorder A maladaptive pattern of substance use leading to clinically significant impairment or distress, as manifested by 2 (or more) of the following, occurring within a 12-month period:
Recurrent substance use resulting in a failure to fulfill major role obligations at work, school, or home Recurrent use in situations in which it is physically hazardous Continued use despite persistent or recurrent social or interpersonal problems caused or exacerbated by the effects of the substance (e.g., arguments with spouse about consequences of intoxication, physical fights)ToleranceWithdrawal Substance taken in larger amounts or over a longer period than intendedPersistent desire or unsuccessful efforts to cut down or control useGreat deal of time is spent in activities to obtain substance, use substance, or recover from its effectsImportant social, occupational, or recreational activities given up or reduced because of substance useSubstance use is continued despite knowledge of having a persistent or recurrent physical or psychological problem that is likely to have been caused or exacerbated by the substanceCraving/strong desire/urge to use substance.
But…… Several DSM-V criteria rarely endorsed by
regular tobacco users Less validity in predicting consequences of
nicotine dependence (e.g. relapse) than nicotine-specific measures such as time-to-first-cigarette after awakening and cigarettes smoked/day (cigs/day)
Nicotine dependence can be diagnosed when a patient experiences a recurrent and periodic wanting, craving, or needing for tobacco (Joe DiFranza).
How Do We Measure Nicotine Dependence
(Symptoms) in Youth?
ND Indicators Multidimensional
Measures ICD-10 criteria
(diagnostic) HONC (theory-based) Stanford Dependence
Index Nonnemaker
Symptom Clusters ND/cravings (loss of
control, failed quit attempt, strong cravings)
Self-medication (helps to feel better, relaxation, gives energy)
Withdrawal symptoms (restlessness, difficulty concentrating, depressed mood)
Nicotine Dependence Scale
Nonnemaker et al., 2004
Why The Interest in ND in Young Smokers?
Five Stages of Onset
Preparatory Trying ExperimentsUses
regularly Dependent
Developattitudesand beliefs
Firstcigarettes
Smokesrepeatedly butirregularily
Smokes atleast weeklyacross a variety of situations
Physiologicneed
No longer smokes
Source: Preventing Tobacco Use Among Young People. A Report of the Surgeon General, 1994.
QuitNo longer smoke
However... Children inhale and absorb as much nicotine/cig
as adults, even at first Tolerance develops soon after first cigarette Children report ND symptoms, cravings, even
before daily smoking Children who quit report withdrawal symptoms
related to number of cigarettes/day Children may have more difficulty quitting than
adults
Cumulative Incidence of First ND Symptoms in 12-13 Year-Olds (n=95)
% w
ith
sym
pto
ms
Month
Source: DiFranza et al. Tobacco Control 2000.
Is It Plausible? Nicotine increases the number
of nicotinic receptors in brain areas associated with pleasure pathways
Neurological changes begin as early as the second dose of nicotine
Speed of changes compatible with early appearance of ND
Role of Nicotine in Natural History of Onset
Factors Psychosocial Environmental
Preparatory TryingExperimen-
talRegular
UseAddictionDependent
NicotineDependenceSymptoms
Non-smoker
Etude NICO/NDIT Ongoing 13-year longitudinal
cohort n=1293 grade 7 students
(age 12-13) in 10 high schools
Baseline reponse: 56% Follow-up response: 94% n=950 blood/saliva DNA;
n=500 parental DNA Anthropometric measures,
BP, parental data, env’t data Among more importnant
contributions: predictors of onset and daily smoking
Predictors of Adolescent Smoking Initiation Younger age Single-parent family status Smoking by parents, siblings,
friends, school staff Stress Impulsivity Lower self-esteem Feeling a need to smoke Not doing well at school Susceptibility to tobacco
advertising Alcohol use Use of other tobacco products Attending a smoking-tolerant
school
Daily smoking Smoking by siblings and
friends Feeling a need to smoke Susceptibility to tobacco
advertising Use of other tobacco
products Self-perceived mental
and physical addiction
O’Loughlin et al. Determinants of first puff and daily cigarette smoking in adolescents. AJE 2009; DOI: 10.1093/aje/kwp179
Trajectories of Cigarette Use Onset
Do subjects follow the same trajectory or are there distinct sub-groups of trajectories?
Is development of ND related to trajectory sub-group?
Background Increased interest in trajectories – is smoking
discrete or process?
Numerous studies report trajectories (i.e., Colder et al. (2001) reported 5 classes in 11-16 year-olds: early rapid late moderate late slow escalators stable light stable puffers
But follow-up is anchored at arbitrary time 0 on a scale of age (not smoking onset) and time intervals between follow-ups are wide
Methods Data drawn from NDIT
1293 students followed every 3 months over 5 years of follow-up
369 baseline never smokers followed over 31 months after initiation
Used latent class growth modeling to describe cigarettes smoked/month over time after first puff
Smoking Trajectories
Rapid escalators (6%)
Moderate escalators (11%)
Slow escalators (11%)
Non-progressing low-intensity onset (72%)
Time to ND in Four Trajectory Classes
Non-progressing low-intensity onset (72%)
Slow escalators (11%)
Moderate escalators (11%)
Rapid escalators (6%)
Natural History of Onset
Natural History of Nicotine Dependence
How quickly do symptoms of nicotine dependence develop in relation to first puff?
In this more “qualitative” study, we used survival analysis to describe time from first puff to milestones in the smoking onset process
Natural History of Smoking Onset
12 24 36 48 Months
Inhalation 2
Whole cigarette 3
0
Smokes monthly9
Smokes weeklyLifetime 100 cigs
19
Smokes daily23
Onset of ND Symptoms
12 24 36 48 Months
Inhalation 2
Whole cigarette 3
0
Smokes monthly9
Withdrawal 12
Smokes daily23
Cravings5
Smokes weeklyLifetime 100 cigs
19
ICD-10 Tobacco dependence
46
Tolerance 14
Early Cessation Milestones
12 24 36 48 Months
Inhalation 2
Whole cigarette 3
0
Smokes monthly9
Withdrawal 12
Smokes daily23
Cravings5
Smokes weeklyLifetime 100 cigs
19
ICD-10 Tobacco dependence
46
Stopped smoking completely and forever Really want to quit 2
Serious quit attempt 3
Not confident quitting21
Aware of difficulty quitting32
Youth Cessation
97% of puffers, 83% of occasionnal smokers, and 33% of daily smokers believe that they are not dependent
97% of puffers, 87% of occasionnal smokers, and 70% of daily smokers believe that they can stop smoking easily
Youth Under-Estimate the Power Youth Under-Estimate the Power of the Puffof the Puff
Source: EQT 2006Source: EQT 2006
Many Novice Smokers Want to Quit… Review of 52 national population-based
studies 1990-2005 on prevalence, frequency, duration of cessation attempts in smokers aged 10-20
68% try to quit each year > half make several attempts Most do not succeed
- 34% relapse within 1 week- 92% relapse within 1 year
Cessation surveillance, research and programs should extend to young adolescents and non-daily smokers
Source: Bancej et al.Source: Bancej et al. Tob. Control 2007
Predictors of Youth Cessation in Longitudinal Studies
Reviewed 4502 titles (1984-2010), 871 abstracts; 9 retained
Difficulties- lack theoretical underpinnings- Differing definitions, measures, measures of effect- findings for many factors inconclusive - many factors unexplored
5 robust predictors‒ no friends who smoke‒ no intentions to smoke ‒ resists peer pressure to smoke‒ older at first cigarette use‒ negative beliefs about smoking.
Source: Cengelli et al. Tob Control 2012;21:355-62.
Socioecologic Study of Cessation Predictors In Adolescent Smokers
Data drawn from NDIT All ever smokers in secondary school (20 cycles) Outcome: stopped smoking for >12 consecutive
months (144 of 308 ever-smokers attained outcome) Data on 37 potential predictors drawn from cycle
before outcome Data on covariates (r>0.2 with exposure of interest) lagged by 2 cycles
Multiple imputation Single participant included multiple times in analytic
database Total of 37 models, one for each potential predictor Used logistic regression within a GEE framework
Potential Predictors (n=37) Selected based on the strength of evidence, availability of data in
NDIT, utility in designing interventions Socio-demographic (sex, age, language, single-parent family,
parental education) Social environment (parent(s) smoke, sibling(s) smoke, friends
smoke, teachers smoke) Psychological (stress, depression, impulsivity, novelty-seeking, self-
esteem, worry about weight) Psychosocial (susceptibility to cig package warnings, to tobacco
ads) Overweight; asthma Lifestyle (alcohol, other tobacco products, illicit drugs, physical
activity (LPA, MPA, VPA), team sports, TV) Nicotine dependence (tolerance, cravings, self-medication,
withdrawal, cigarette duration, cigarette intensity Context (tolerance of smoking in school, community (depanneurs,
restaurants).
Baseline Characteristics Sociodemographic % Male 37 French 19 Single-parent 14 Parent(s) completed university 42Smoking in social environment Parent(s) smoke 44 Sibling(s) smoke 30 Friends smoke 87 Teachers smoke 79Psychosocial Cigarette package warnings make me afraid to smoke (not true)
44
Cigarette advertisements make me want to smoke (true)
23
Overweight 25Asthma 19Lifestyle Alcohol use 74 Other tobacco products 45 Illicit drugs 35 Team sports 56
Findings Abstinence varied from 0-52% Intervention > control in 14/16 comparisons 4/16 statistically significant (2/4 not
biochemically validated)- 3 school-based programs- 1 motivational interviewing in health care
setting
But…..many difficulties with this literature (intervention concept, small samples, short follow-up, differing definitions)
Much more research is needed
Results from Logistic Regression Models of the Association Between Predictor Variables and Cessation in Adolescents
Predictor variable AdjustedOR (95%
CI)
Covariates included in multivariate model
Male1.8 (1.3, 2.5)
age, depression, VPA, worry about weight, other tobacco products
Age (y)1.3 (1.1, 1.5)
sex, cravings, withdrawal, cigarette intensity, illicit drugs, # months smoking
Parent(s) smoke 0.7 (0.5, 0.9) age, sexFamily stress 0.7 (0.5, 0.9) depression, stress, age, sexWorry about weight 0.6 (0.5, 0.8) depression, stress, age, sexCig package warnings make me afraid to smoke 1.4 (1.0, 1.9) age, sexOverweight 0.7 (0.5, 0.9) age, sexIllicit drug use 0.5 (0.4, 0.7) craving, # months smoking, age, sexTeam sports 1.5 (1.1, 1.9) VPA, age, sexTolerance 0.6 (0.4, 0.9) craving, self-medication, age, sexCraving
0.9 (0.9, 0.9)
tolerance, self-medication, withdrawal, # yrs smoking, cig intensity, cig ads, illicit drugs, age, sex
Does Anything Work? Review of 16 RCTs (2001-
6) including 6623 youth aged 12-20 - 11 behavioral - 1 acupuncture- 4 pharmacologic
Outcome: 5-day point prevalence of abstinence
12/16 validated by CO/saliva cotinine
Drop-out: 8-64%
Source: Gervais et al. Drogues, santé, et société 2007;6:ii1-ii26.
Rethink intervention?
Timing - target novice smokers before cravings? (prevention vs cessation)
Content - take some/all cessation predictors into account?
(team sports? dependence)
Tailored targeting? (families, girls (overweight)/boys)
Mode of delivery? (individual, legislation, social norms)
Reflections First puff is dangerous for many
children
ND symptoms develop very rapidly in many children
Subjects with escalating trajectories developed ND much faster
Not possible to know which children will escalate
Intervention programs must move beyond social learning underpinnings if children experience physiological ND symptoms
What’s Next?
Research in Next Ten Years Well-powered longitudinal studies on
risk for onset to develop better underpinnings for prevention (incorporating socio-ecological and life course perspectives)
Natural course of onset, ND, cessation
Cessation in children and adolescents (NRT and Zyban for children?)
Studies on methods (what is smoking in kids? Cessation?)
More qualitative research Genes, genes, and more genes
(gene-environment, gene-gene interactions, epigenetics)
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