Effects of Drugs of Abuse on the Developing Brain

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Effects of Drugs of Abuse on the Developing Brain
Ken Winters, Ph.D. Collaborating Investigator,
Treatment Research Institute Professor,
Department of Psychiatry, University of
Minnesota winte001_at_umn.edu The Downtown Club of
Philadelphia, November 23, 2004
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Overview

• Scientific study of brain development can help us
  understand adolescent behavior
• risk-taking and poor judgment
• vulnerability to drug abuse
• Relevance to parenting, prevention and treatment

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• Keep in mind..
• The research on neuro- development is in the
  early stages
• Many key human studies on youth can not be
  conducted because of ethical considerations

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Suggested Readings

• www.thebrain.mcgill.ca/flash/index_d.html
• Dubuc, B. (2004). The brain from top to bottom
• www.drugabuse.gov/Published_Articles/
• Leshner A. (2000). Oops. How casual drug use
  leads to addiction. National Institute on Drug
  Abuse, September, 2000.
• Why do they act that way? A survival guide to
  the adolescent brain for you and your teen
• Walsh, D. (2004). NY Simon Schuster.
• What makes teens tick?
• Wallis, C. (May 10, 2004). NY Time magazine.
• The adolescent brain and college drinker
  Biological basis of propensity to use and misuse
  alcohol.
• Spear, L. (2002). Journal of Studies on Alcohol,
  14, pp. 71-81.

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Some Background
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What is adolescence?
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Substance Use by Youth - Prior Month
2002(Monitoring the Futures, 2003)
Grade Alcohol Marijuana Any
Illicit 8 20 8 10
10 35 18 21 12
49 22 25
Substance Abuse/Dependence rates vary 3-15
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Can Addiction be Prevented by Delaying Drug Use
Onset?

• Every year use of a substance is delayed, the
  risk of developing a substance use disorder is
  reduced.

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Percentages of Past Year Alcohol Dependence or
Abuse Among Adults Aged 21 or Older, by Age of
First Use (SAMHSA, 2004)
Percent
Age Started Drinking
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• Adolescence is a period of profound brain
  maturation.
• It was believed that brain development was
  complete during childhood
• The maturation process is not complete until
  about age 24!!!

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Construction Ahead

• During late childhood, neurons get bushier and
  increase in the number of connections.
• At about age 11 in girls and age 12½ in boys,
  this thickening undergoes pruning.
• At the same time, the myelin sheaths that encase
  nerve cells thicken.
• Myelin sheaths are like insulation on a wire
  they make nerve cell transmissions faster and
  more efficient
• Net effect when complete is faster, yet fewer,
  connections in the brain.

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Construction Ahead
Pruning occurs in stages, from back of the brain
to the front
amygdala
judgment
emotion
motivation
physical coordination sensory processing
prefontal cortex
nucleus accumbens
cerebellum
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Age 24
motivation
emotion
physical coordination sensory processing
judgment
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Arrested Development

• Back of brain matures before to the front of the
  brain
• sensory and physical activities favored over
  complex, cognitive-demanding activities
• propensity toward risky, impulsive behaviors
• group setting may promote risk taking
• poor planning and judgment

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Arrested Development

• Back of brain matures before to the front of the
  brain
• activities with high excitement and low effort
  are preferred
• poor modulation of emotions (hot emotions more
  common than cold emotions)
• heightened interest in novel stimuli

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• Neurodevelopment likely contributes to.
• gt risk taking (particularly in groups)
• gt propensity toward low effort - high excitement
  activities
• gt interest in novel stimuli
• lt capacity for good judgment weighing
  consequences

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Are adolescents more susceptible to alcohol than
adults?

• Adult studies suggest that the areas of the
  adolescent brain that are remodeled are sensitive
  to the effects of alcohol
• Four pieces of evidence

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Are adolescents more susceptible to alcohol than
adults?

• Adolescent rats are less sensitive to the
  sedative and motor impairment effects of
  intoxication

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Supporting Human Studies
1. Reduced sensitivity to intoxication
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Comparison of Alcohol Dependence Rates

• Current (Past Year) Adults1 17-202
  18-193
• Alcohol Dependence 7.2 14.6 10.5
• 1 NRC Report, 1999
• 2 NY State Household, 1993
• 3 MN Student Survey, 1995

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Survey Data Suggest that Adolescents Are Less
Sensitive to Alcohols Effects
Monitoring the Future, 2001
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Are adolescents more susceptible to alcohol than
adults?

• Adolescent rats are more sensitive to the social
  disinhibition induced by alcohol use

Sure!
Wanna look for some cheese with me?
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Are adolescents more susceptible to alcohol than
adults?

• Adolescent drunk rats perform worse on memory
  tasks than adult drunk rats

Ugh??
converts information to memory
disrupts the hippocampus brain damage in the PFC
planned thinking
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Supporting Human Studies
3. Greater adverse effects to cognitive
functioning
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Alcohols Effects
(Brown, 2002 Wuethrich, 2001)

• Adolescents with a history of extensive alcohol
  use, compared to a control group.
• Reduced hippocampus volume (10-35)
• Less brain activity during memory tasks

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Are adolescents more susceptible to alcohol than
adults?

• Hyperexcitability issue
• Alcohol relieves hyperexcitability state
• Relief is temporary continued seeking of
  alcohol is reinforced
• Hyperexcitability is a key characteristic of
  conduct disorder, ODD and ADHD, which are often
  co-morbid with alcohol use disorders
• Hyperexcitability.
• may have its origins in neurological deficits
• found in non-alcoholic relatives - suggests
  inheritance of this trait

ADHD
ODD
Sub Use Dis
Con Dis
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Are adolescents more susceptible to alcohol than
adults?
Increases reinforcing properties

• Reduced sensitivity to intoxication
• Increased sensitivity to social disinhibitions
• Medicates hyperexcitability

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Are adolescents more susceptible to alcohol than
adults?
Greater deficits

• Greater adverse effects to cognitive functioning

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• Neurodevelopment likely contributes to.
• gt risk taking (particularly in groups)
• gt propensity toward low effort - high excitement
  activities
• gt interest in novel stimuli
• lt capacity for good judgment weighing
  consequences

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Implications of this new scienceEnhancing
parenting, prevention and treatment

• Will parents, health service providers and young
  people benefit by this knowledge about basic
  principles of brain development?
• The developing brains software does not include
  program language that says on second thought

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Implications of this new scienceEnhancing
parenting, prevention and treatment

• Will young people benefit by learning about basic
  principles of brain development?
• Will young people be influenced by the science
  that suggests drug use has a deleterious effect
  on the developing brain?
• Going beyond this is your brain on drugs

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THANK YOU!winte001_at_umn.edu