Adolescents and Substance Abuse

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Adolescents and Substance Abuse

• Dr. Cynthia Kuhn
• Department of Pharmacology and Cancer Biology
• Duke University Medical Center

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Drug Use Begins in Adolescence
Percent Using in Past Month
Alcohol
Cigarettes
Marijuana
Hallucinogens
Prescription Rx
Age in Years
National Household Survey on Drug Use and Health
2008
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Tobacco Use is Maximal in Adolescence
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Addictive Drug Use Peaks during Adolescence
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Alcohol Use Peaks during Late Adolescence
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The earlier people start drugs, the more likely
they are to develop abuse
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Adolescence What is Going On?

• Social development importance of peers
• Hormonal development
• Sex hormones
• Stress hormones
• Brain development

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Adolescent Brain is Still Changing
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Phases of Brain Development
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What Functions are Changing?

• Response to Reward
• Response to Punishment
• Neural Circuits that Plan Ahead

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Triad of Motivated Behavior
BEHAVIOR
Executive Function
Reward
Avoidance
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Reward Areas Develop Before Thinking Areas
Sommerville and Casey, Curr. Opinion Neurobiol
20236 (2010)
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Adolescents Dont Like to Wait for Reward
Adapted from Psychological Science 533 (1994)
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Adolescents are Less Sensitive to Aversive
Experiences (Punishment!)

• Adolescent rats do not avoid taste associated
  with unpleasant experience (nausea)

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Reward is More Effective than Punishment in
Adolescence
Punishment
Reward
Adolescence
Adult
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Adolescents Dont Change Losing Strategies
Cauffman et al, Develop. Psychology 46193 (2010)
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Adolescents Do Not Avoid Bad Outcomes
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Adolescents are Impulsive
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The Yin/Yang of Adolescent Decision Making

• Helpful
• Still fine tuning connections- primed to learn
• Impulsive try something just because
• Risk taking will try new things without
  assurance of success
• Arent inhibited by low probability of success

• Not helpful
• Final connections for good decision making are
  not done
• Risk taking- will try new things just because
  they are new
• Long-term outcome less important
• Bad outcome less important

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What is Different about Addiction Mechanisms in
Adolescent Brains?

• Respond more to rewards
• Respond less to punishment -different processing
  of negative emotions
• Risk taking and Novelty seeking

Highs are higher
Lows are not as Low
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So Is the Brain Primed for Addiction in
Adolescence?
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Addiction Is a Process of Brain Adaptation
Drug use Reward
ADDICTION Withdrawal, Craving
Reward circuit Adapts
Need drug to Feel Good at all
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Addiction is NOT just Dopamine

• Components of Addiction
• Rewarding effects of the drugs dopamine
• Tolerance and dependence- withdrawal
• Impaired priority setting/decision making
  craving, compulsive use

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Neural Basis of Addiction
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All Addictive Drugs Activate This Circuit
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All Addictive Drugs Increase Dopamine Levels
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Addiction Is a Process of Brain Adaptation
Drug use Reward
ADDICTION Withdrawal, Craving
Reward Circuit Adapts
Need Drug to Feel Good at all
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Reward System Adaptations in Addiction
DA Target Neuron
DA Receptors
Constant DA Release
Dopamine Neuron
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Dopamine Receptors Are Decreased in Addicts
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Addictive Drugs Cause Long Lasting Changes in
the Brain
Kalivas and Volkow, Arch Gen Psy. 162 1403
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Addiction Is a Process of Brain Adaptation
Drug use Reward
ADDICTION Withdrawal, Craving
Reward Circuit Adapts
Need Drug to Feel Good at all
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Executive Function Changes in Addiction Drugs
Become Priority

• Increased impulsivity Do things without
  considering the outcome
• Impaired memory- Cant keep things in mind while
  considering a decision
• Difficulty shifting priorities
• Risky decision making

Berridge et al, Phil Trans. R. Soc B. 3633257
(2008)
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Addicts Cant Change Losing Strategies
A
B
Win Big, Lose Overall
C
D
Win Small, Win Overall
. J. Math. Psychol 5428 (2010)
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Addiction Is a Process of Brain Adaptation
Drug use Reward
ADDICTION Withdrawal, Craving
Reward Circuit Adapts
Need Drug to Feel Good at all
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Craving and Misery of Withdrawal From Activation
of Stress Axis

• Chronic drug exposure triggers stress axis
• Involves stress peptide CRF
• Amygdala sends messages to cortex motivates
  more drug taking

Chronic Addictive Drugs Activate the Stress Axis
in the Brain
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Summary Key Processes in Addiction

• Rewarding effects of drugs
• Adaptation to drugs brain biochemistry and
  structure changes
• Disturbed decision making
• Craving associated with Withdrawal activation
  of stress axis

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What is Different in Adolescent Response to
Addictive Drugs?
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Cocaine Increases Dopamine More in Adolescents
Walker and Kuhn, Neurotox Teratol 30 412
(2008)
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Adolescents Avoid Drugs that are Aversive Less
than Adults
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More Lasting Gene Changes after Nicotine Exposure
during Adolescence
Doura et al, Neuroscience in press, 2010
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Summary of Addiction Vulnerabilities in
Adolescents

• Risk taking more likely to use drugs
• Less likely to inhibit behavior (refuse when
  offered)
• Balance of drug effects different biased toward
  pleasant effects
• Biochemical changes in brain may be more
  long-lasting

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Not Every Adolescent is Equally at Risk
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Model of Adolescent Drug Use
Adolescent Substance Abuse
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Temperament Environment Influence Drug
Involvement
Alcohol abuse from Age 12 to 18
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Does This Mean that Behavior Changes is
Impossible? NO
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Who can Influence Adolescents?

• Peers (of course)
• Parents especially if they practice what they
  preach
• Trusted adults (YOU!)

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What Influences Increase or Decrease Drug
Involvement

• Increase
• Parents using at home
• No parent limit setting
• Poor school involvement
• Deviant peers

• Decrease
• Life Satisfaction
• Goal setting
• Supervising parents
• Trusted adult
• School engagement
• Sports
• Involvement in church or other activities

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And remember, Biology is not Destiny
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Dr. Cynthia Kuhn

• ckuhn_at_duke.edu

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Effects of Addictive Drugs are a Balance of
Reward and Aversion
Initial Drug Experience DA dominant
Addiction CRF Dominant
CRF Amygdala
DA