Effects of Drugs on the Brain
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Transcript of Effects of Drugs on the Brain
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
The Downtown Club of Philadelphia, November 23, 2004
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
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
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 teenWalsh, 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.
Some Background
What is adolescence?
Grade Alcohol % Marijuana % Any Illicit %
8 20 8 10
10 35 18 21
12 49 22 25
Substance Use by Youth - Prior Month 2002
(Monitoring the Futures, 2003)
Substance Abuse/Dependence rates vary:
3-15%
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.
Percentages of Past Year Alcohol Dependence or Abuse Among Adults Aged 21 or Older, by Age of First Use (SAMHSA, 2004)
1615
9
4.22.6
0
5
10
15
20
<12 yrs 12-14 yrs 15-17 yrs 18-20 yrs 21+ yrs
Age Started Drinking
Perc
en
t
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!!!
• 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.
Construction Ahead
Construction Ahead
motivation
emotion
judgment
cerebellum
amygdala
nucleus accumbens
Pruning occurs in stages, from back of the brain to the front
prefontal cortex
physical coordination; sensory processing;
motivationemotionjudgment
Age 24
physical coordination; sensory processing;
• 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
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
Arrested Development
• Neurodevelopment likely contributes to…. • > risk taking (particularly in
groups)
• > propensity toward low effort - high excitement activities
• > interest in novel stimuli
• < capacity for good judgment & weighing consequences
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
Are adolescents more susceptible to alcohol than
adults?
1. Adolescent rats are less sensitive to the sedative and motor impairment effects of intoxication
Supporting Human Studies
1. Reduced sensitivity to intoxication
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
Comparison of Alcohol Dependence Rates
Survey Data Suggest that Adolescents Are Less Sensitive to Alcohol’s Effects
148
26 2430 32
0
20
40
60
80
100
8th Graders 10th Graders 12th Graders
5+ drinks in row, past 2 weeks
Been drunk past month
Monitoring the Future, 2001
Are adolescents more susceptible to alcohol than
adults?
2. Adolescent rats are more sensitive to the social disinhibition induced by alcohol use
Wanna lookfor some cheese
with me?
Sure!
Are adolescents more susceptible to alcohol than adults?
3. Adolescent drunk rats perform worse on memory tasks than adult drunk rats
Ugh??
disrupts the hippocampus
brain damage in the PFC
converts informatio
n to memory
planned
thinking
Supporting Human Studies
3. Greater adverse effects to cognitive functioning
Alcohol’s Effects
• Adolescents with a history of extensive alcohol use, compared to a control group….
Reduced hippocampus volume (10-35%)
Less brain activity during memory tasks
(Brown, 2002; Wuethrich, 2001)
Are adolescents more susceptible to alcohol than
adults?
4. 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
Con Dis
Sub Use Dis
Are adolescents more susceptible to alcohol than adults?
1. Reduced sensitivity to intoxication
2. Increased sensitivity to social disinhibitions
4. Medicates “hyperexcitability”
Increases reinforcing properties
Are adolescents more susceptible to alcohol than adults?
Greater deficits
3 Greater adverse effects to cognitive functioning
• Neurodevelopment likely contributes to…. • > risk taking (particularly in
groups)
• > propensity toward low effort - high excitement activities
• > interest in novel stimuli
• < capacity for good judgment & weighing consequences
Implications of this new science:
Enhancing parenting, prevention and treatment
1. Will parents, health service providers and young people benefit by this knowledge about basic principles of brain development?
• The developing brain’s software does not include program language that says “on second thought”
Implications of this new science:
Enhancing parenting, prevention and treatment
1. Will young people benefit by learning about basic principles of brain development?
2. 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”
THANK [email protected]