Epidemiology of Adolescent Drug Use

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Epidemiology of Adolescent Drug Use
Martin Frisher Department of Medicines
Management Keele University 24th January
2005 Department of Addictive Behaviour
Psychological Medicine St. George's Hospital
Medical School
2
Topics covered in this presentation

• Define Epidemiology, Adolescence and Drug
  Use/Addiction
• Epidemiology-Basic Concepts
• Characteristics of current adolescent drug use in
  the UK
• UK vs European adolescent drug use
• Does early drug use act as a gateway to hard
  drug use?
• Qualitative Research /Subjective experience of
  drug use

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Epidemiology Definition

• Scientific discipline studying the incidence,
  distribution, and control of disease in a
  population. Includes the study of factors
  affecting the progress of an illness, and, in the
  case of many chronic diseases, their natural
  history. http//www.sleepnet.com/definition.html
• The study of the incidence, distribution and
  determinants of an infection, disease or other
  health-related event in a population.
  Epidemiology can be thought of in terms of who,
  where, when, what, and why. That is, who has the
  infection/disease, where are they located
  geographically and in relation to each other,
  when is the infection/disease occurring, what is
  the cause, and why did it occur
  www.un.org/Pubs/CyberSchoolBus/special/health/glos
  sary/

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Epidemiology and Drug Use

• Not all commentators accept the concept of drug
  epidemiology as it implies that drug use is a
  disease or even analogous to a disease.
• Alternative view - essentially a voluntary (or
  learned) behaviour where the concept of
  addiction is a device for avoiding
  responsibility.
• In essence, a want derived from memory than
  that a have to underlaid by pharmacology.

The Myth of Addiction, John Davies 1982
5
Distribution of cholera deaths, London 1850
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Ratio of cigarettes smoked doctorsgeneral
population
Ratio of mortality doctorsgeneral population
Source Foundations of Epidemiology 2nd Ed OUP,
Lilienfield and Stolley (1994), p 9-10
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Drugs, Set and Setting

• Effects of a drug are determined by
• the drug itself (quantity, quality, frequency of
  use, method of ingestion)
• the set (personality, mood, reasons for use,
  memories, expectations)
• the setting (physical, social and cultural
  context of use)

Drugs, Set and Setting, N Zinberg, 1984
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The Doors of Perception. Aldous Huxley 1954

• If the doors of perception were cleansed
  everything wouldappear to man as it is,
  infinite. William Blake
• At breakfast that morning I had been struck by
  the lively dissonance of the flowers colours.
  But that was no longer the point.... I was seeing
  what Adam had seen on the morning of his
  creation-the miracle, moment by moment, of naked
  existence.

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Trainspotting. Irvine Welsh, 1994
You don't have to worry about bills, about food,
about some football team that never wins, about
human relationships and all the things that don't
really matter when you've got a sincere and
truthful junk habit".
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Factors said to be associated with drug use/non
drug use
www.drugsprevention.net
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Substance Abuse Definition

• The uncontrollable or excessive abuse of
  addictive substances, such as (but not limited
  to) alcohol, drugs or other chemicals and the
  resultant physiological and/or psychological
  dependency which develops with continued use.
  www.bcbsal.com/ua/definitions.htm

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DSM-IV - DEFINITIONS OF SUBSTANCE ABUSE AND
DEPENDENCE2002 UPDATE

• 3 from
• 1. Tolerance
• 2. Withdrawal
• 3. Large amounts over a long period
• 4. Unsuccessful efforts to cut down
• 5. Time spent in obtaining the substance replaces
  social, occupational or recreational activities
• 6. Continued use despite adverse consequences

Diagnostic and Statistical Manual of Mental
Disorders - Fourth Edition (DSM-IV), published by
the American Psychiatric Association, Washington
D.C., 1994
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AdolescenceDefinition

• Stage of growth and development ranging from
  about 11 or 12 years old to 17 or 18 years old in
  which major physiologic, cognitive, and
  behavioural changes take place. According to some
  theorists, important developmental tasks need to
  be accomplished (e.g., developing an identity,
  becoming independent, etc.). http//www.gainsctr.c
  om/curriculum/juvenile/glossary.htm
• the stage of psychological development between
  the start of puberty and the time the individual
  accepts the full responsibilities of being an
  adult in a given society
• http//lms.thomsonelearning.com/hbcp/glossary/

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Computer forecast of drug diffusion
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Increased availability of drugs 1978-2000
The road to ruin? Sequences of initiation into
drug use and offending by young people in
Britain. Stephen Pudney Home Office Research
Study 253. December 2002
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Roots of the current epidemic

• 1961 Government Inter-departmental Report
• ''on the evidence before us the incidence of
  addiction to dangerous drugs is very smallthere
  seems no reason to think that any increase is
  occurring
• Addict population about 400mostly elderly people
  who contracted the habit through medical
  treatment and 70 doctors and nurses who had
  access to drugs.
• Perhaps a dozen non medical addicts
• Now - social problems generated by severely
  dependent drug misusers 3-4 billion

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Longitudinal follow up of young people in
Englandhave you been offered drugs?
Illegal leisure the normalisation of adolescent
recreational drug use. Parker, Aldridge and
Measham 1998
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Survey among school pupils aged 11-15National
Centre for Social Research and the National
Foundation for Educational Research 2001
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British Crime Survey 1996-2002age 16-24
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Continuation rates (ever - year/month) among
adults age 16 1997 Dutch Household Survey
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Most difficult to give up (among those who
consume in previous year)
Night life and recreative drug use in Europe. A
study in 10 European Cities 1998. (Calafat et al
1999).
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British Crime Survey 1996-2002age 16-24
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European School Survey Project on Alcohol and
Other Drugs (ESPAD)proportion of students
lifetime experience of illicit drugs 1995-1999
1999
1995
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European School Survey Project on Alcohol and
Other Drugs (ESPAD)proportion of students drunk
2 times in last month 1995-1999
1999
1995
The 1999 ESPAD report Alcohol and other drug
use among students in 30 European countries, B.
Hibbell, B. Andersson, S. Ahlström, O.
Balakireva, T. Bjarnson, A. Kokkevi, M. Morgan,
the Swedish Council for Information on Alcohol
and Other Drugs (CAN), the Pompidou Group of the
Council of Europe, December 2000.
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European School Pupils -1999Use of alcoholic
beverage 20 times in last year
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European School Survey Project on Alcohol and
Other Drugs (ESPAD)daily smoking among pupils
aged u-14 1999
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European School Survey Project on Alcohol and
Other Drugs
Ever use of drugs 1999
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Regional Drug Misuse Databases in Englandnumber
of new or renotified clients 1993 and 2001
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Drug Offences in England 2001by age category of
offender
Number of cases 110,000
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Drug related deaths in England and
Wales(poisoning and overdoses)
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Deaths by age and gender
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Volatile Substance Abuse

• Children aged 14-18 accounted for 55 of all VSA
  deaths in the period 1971-99.
• New legislation to tighten up on the sale of
  butane lighter refills has been introduced.
• Increase in VSA?

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Psychiatric comorbidity in general practice
change 1993-1998 by age group
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Psychiatric comorbidity in general practice
change 1993-1998 by psychiatric condition
35
Risk of mortality in a cohort of British male
physicians
Source Epidemiology in Medicine Little Brown,
Toronto , Hennekens Buring (1987), p 94
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Stoke/Newcastle Study of Adolescent Drug Users
Age at Interview and LPDU
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Precursors and consequences of problematic drug
use a study of young people accessing designated
drug services in England

• Study Design and Method
• Method cross-sectional study
• Structured questionnaire (700 variables)
• Sample young drug users and parents/guardians
• Sites Stoke-on-Trent and Newcastle-upon-Tyne
• Sample 103 young drug users (response rate 95)
  46 parents (response rate 70).
• Age range 11-20 (average 16)
• Interviews with young people and parents/carers
  took approximately 30-40 minutes

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Level of Problematic Drug Use
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Potential Risk Factors
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Structural Equation ModelPrecursors of the level
of drug use
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Explaining drug use

• Around 50 of the variance of respondents LPDU
  can be explained by a range of factors. The
  other 50 is due to factors which we have not
  been able to account for. This may be because

• variables were not measured in sufficient detail
  (e.g. our measures of family conflict were too
  crude)
• variables were not measured in this study (e.g.
  personality)
• variables are beyond the reach of current
  scientific methods
• some things might be intrinsically not measurable
  (an individuals need for esteem)

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Hierarchy of risk?
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Children's hedonic response to the smell of
alcohol Effects of parental drinking habits.

• Infants who had more exposure to alcohol mouthed
  an ethanol-scented toy more compared with less
  exposed infants.
• Older children's preference for the odor of beer
  varied as a function of the escape drinking of
  their parents.
• Children who lived in a household in which one or
  both parents drank alcohol to escape were
  significantly more likely to dislike the odor
  bottle that contained alcohol when compared with
  children whose parents did not drink to escape.
• Some early learning about alcohol is based on
  sensory experiences and some on the emotional
  context in which their parents experience alcohol.

Mennella JA, Garcia PL Alcohol Clin Exp Res 2000
Aug24(8)1167-71
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Parental Alcohol Use in the UK

• A large number of children, estimated at 920,000,
  are currently living in a home where one or both
  parents misuse alcohol
• 6.2 of adults have grown up in a family where
  one or both of their parents drank excessively
  (NACOA 2000).

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Gateway from cannabis to...

• Many hard drug users have followed a similar path
  from cigarettes and alcohol, to cannabis, to
  heroin and cocaine. This has led some researchers
  to argue that soft drugs provide a "gateway" to
  harder substances.
• It might be that cannabis users have a genetic
  profile that predisposes them both to cannabis
  use and to harder drugs, or a personal history
  that does the same.
• Research shows that the gateway is real, so what
  implications does this have for drug laws? "This
  finding can be used as the bases for quite
  opposite drug policies www.newscientist.com/news/
  

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Survey Data Cannabis and Cocaine

• An American study determined that from the
  population of cannabis users 17 had used cocaine
  whereas from the population of non-cannabis users
  only 0.2 had used cocaine.
• The vast majority of cannabis users (83) do not
  go on to use cocaine. The study actually shows
  the opposite of what it is often purported to
  prove in effect, for most users, cannabis is
  'clearly a "terminus" rather than a "gateway"
  drug'www.ukcia.org/culture/effects

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Psychological and social sequelae of cannabis and
other illicitdrug use by young people a
systematic review of longitudinal,general
population studies Lancet 2004 363 157988

• Both cannabis use and adverse psychosocial
  outcomes seem to share common antecedents related
  to various forms of childhood adversity, and
  factors relating to peer group and family.
• The relation between cannabis use and harm might
  simply reflect these associations cannabis use
  could be a marker, rather than a cause, of a life
  trajectory more likely to involve adverse
  outcomes.
• Discounting confounding is probably the most
  serious interpretational challenge in
  observational epidemiology.

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1998/99 UK Youth Lifestyles Survey (YLS)

• The average age of onset for truancy and crime
  are 13.8 and 14.5 years respectively, compared
  with 16.2 for drugs generally and 19.9 years for
  hard drugs.
• Thus crime tends to precede drug use rather than
  vice versa.
• Early soft drug use and later hard drug use may
  be joint expressions of the same underlying
  personal problem rather than a consequence of a
  causal influence of soft drug use on the
  subsequent desire for harder drugs.
• Gateway effect minimal, therefore reclassify
  cannabis?

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Twins Study Supports 'Gateway Theory'

• 311 sets of same-sex twins in which only one twin
  had smoked marijuana before age 17.
• Early marijuana smokers were found to be up to
  five times more likely than their twins to move
  on to harder drugs
• Associations between early cannabis use and later
  drug use and abuse/dependence cannot solely be
  explained by common predisposing genetic or
  shared environmental factors.
• cannabis may change your brain or makes you crave
  other drugs
• other potential mechanisms, including access to
  drugs, willingness to break the law and
  likelihood of engaging in risk-taking behavior.
• Escalation of Drug Use in Early-Onset Cannabis
  Users vs Co-twin Controls JAMA, Jan 2003 289
  427 - 433.

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Preventing Drug Use
What we know now from our own longitudinal
studies is that if we create more opportunities
for young people to be engaged in positive
pro-social waysin family, in school, in
classroom, in neighborhoodif we ensure they have
the skills they need developmentally to master
those opportunities they have, and if we are
consistent in reinforcing and recognizing
them...for doing a good job, they become more
committed and attached to school, more bonded to
family, more committed and attached to the
neighborhood. And once theyve bonded, theyre
more likely to live according to healthy beliefs
and clear standards. David Hawkins.
Adolescent Substance Abuse A Public Health
Priority An evidence-based, comprehensive, and
integrative approach Center for Alcohol and
Addiction Studies Brown University August 2002
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Positive experiences (Aged 18)
STARTING, SWITCHING, SLOWING AND STOPPING Fiona
Measham Howard Parker Judith Aldridge Home Office
1998
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Negative experiences (Aged 18)
STARTING, SWITCHING, SLOWING AND STOPPING Fiona
Measham Howard Parker Judith Aldridge Home Office
1998
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Switching drugs
One reason for switching between drugs mentioned
by our respondents ..is perceived and projected
image. The young people are keenly aware of
how their behaviour might be construed by those
around them as an indication of age and maturity.
Such concerns about self image are reflected in
the ways in which the effects of drugs for them
are linked to issues of maturity and immaturity,
self control and disinhibition.
STARTING, SWITCHING, SLOWING AND STOPPING Fiona
Measham Howard Parker Judith Aldridge Home Office
1998
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Parental substance use disorder, mediating
variables and adolescent drug use a
non-recursive model. Hoffmann JP, Su SS.
Addiction 1998 Sep93(9)1351-64

• AIMS Examine the effects of parental
  psychoactive substance use disorder (PSUD) on the
  relationships among stressful life events, family
  attachment, peer drug use and adolescent drug
  use.
• FINDINGS Adolescents from PSUD families were at
  heightened risk of stressful life events, peer
  drug use, attenuated family attachments and drug
  use during the first follow-up period. In turn,
  peer drug use was strongly associated with drug
  use during the second follow-up period. However,
  drug use during the first follow-up also led to
  greater peer drug use and attenuated family
  attachment during the second follow-up period.
• CONCLUSIONS Parental psychoactive substance use
  disorder puts adolescents at significant risk of
  becoming embedded in a cycle of drug use,
  associations with drug using peers, and poor
  family relations.

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Developmental analysis of sociodemographic,
family, and peer effects on adolescent illicit
drug initiation. Guo J et al Am Acad Child Psy
41 (7) 838-845 Jul 2002

• OBJECTIVE examine the effects of
  sociodemographic, family, and peer predictors on
  the developmental patterns of illicit drug
  initiation from ages 12 to 21 years.
• METHOD A gender-balanced, ethnically diverse
  urban sample of 808 children in Seattle was
  surveyed at age 10 in 1985 and followed
  prospectively to age 21 in 1996.
• RESULTS The risk for initiating illicit drug use
  increased steadily from ages 12 to 21. High
  family conflict, low family bonding, and high
  peers' antisocial activities predicted higher
  risk of initiation across this developmental
  period. The effect of family bonding began to
  decline after age 18, while the effect of peers'
  antisocial activities began to increase after age
  15. Few gender and ethnic differences were found.
• CONCLUSIONS Parents should create a warm and
  supportive family environment with appropriate
  supervision and control throughout adolescence.
  Association with antisocial peers should be
  reduced, especially in high school. Interventions
  addressing these family and peer factors should
  have beneficial effects across gender and ethnic
  groups.

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Vulnerable young people andtheir vulnerability
to drug misuse

• Many participants felt that nothing would have
  prevented them from taking drugs when they did as
  they wouldnt have listened to anyone at the
  time.
• Also many felt that they would not need the help
  of outside agencies to stop taking drugs if they
  should decide to do so they felt that their
  drug taking wasnt a problem and that they could
  stop when and if they wanted to.

Vulnerable young people and drugs Opportunities
to tackle inequalities. DrugScope 2001 (See
Chapter 2 by Margaret Melrose and Isabelle Brodie
(University of Luton)
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Drug Education

• Educating Children About the Risks Associated
  With Drugs Can Delay or Avoid the Start of
  Experimentation (United Kingdoms Anti-drugs
  Coordinators Annual Report 2000/01 2001).
• Abstainers by and large tended to think that the
  drugs education they received in school was
  valuable and informative whereas users were less
  appreciative of what they had received (Measham
  et al 1998).
• 'Evaluations That Have Attempted to Demonstrate
  Results in Terms of Reducing or Preventing Drug
  Use Have Proved Inconclusive'' (Locatenet 2001)
• 'Outcomes'at Barely More Than the Anecdotal
  Level'. Lloyd and Joyce (1999)
• Anti-drugs Campaigns Are More Likely to
  Encourage Young People to Experiment With Drugs
  (Plant 2002)

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Adolescent Drug Use EpidemiologyConclusions (1)

• 400 drug related deaths?
• 4,000 people under 20 being treated
• Increasing comorbidity in general practice
• Increasing number of young people found guilty of
  drug offences
• UK has high levels of smoking, alcohol and drug
  use by European standards
• Drug use among young people has remained stable
  from 1996-2001

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Adolescent Drug Use EpidemiologyConclusions (2)

• What is drug dependence and how should it be
  measured?
• Risk factors are well known but how much do they
  explain?
• How modifiable are the risk factors?
• More sophisticated models require extensive data
• How does qualitative data enhance understanding?
• Is there a gateway effect?

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Adolescent Drug Use EpidemiologyConclusions (3)

• Reasons and causes are quite different.
• New outbreaks of drug use appear to be supply led
  rather than demand driven.
• Adolescence is becoming longer and more complex,
  drug use becoming normalised.
• Storm and stress visions of adolescence leave
  little room for choice and decision making.
• Are government targets linked to epidemiology?