Drugs and the Adolescent Brain Ken Winters, Ph.D. University of Minnesota Treatment Research Institute ASP Workshop 2005

Emerging Science: Teen Brains Are Still “Under Construction” New insights about: Why teenagers take risks and show poor judgment How teenagers may be highly vulnerable to substance abuse These findings can help parents, policy makers

 Adolescence is a period of profound brain maturation.  We thought brain development was complete by adolescence  We now know… maturation is not complete until about age 24!!!

An Immature Brain = Less Brakes on the “Go” System

Growth of the brain’s nerve cells (neurons) occurs through late childhood 1,000,000,000,000,000 possible connections. Around 11 – GIRLS; 12½ - BOYS: Some of these connections are pruned off. Construction Ahead

When the pruning is complete, the brain is faster and more efficient. But… during the pruning process, the brain is not functioning at full capacity Construction Ahead

Motivatio n Emotio n Judgment Cerebellum Amygdala Nucleus Accumbens Maturation starts at the back of the brain.. and moves to the front Prefrontal Cortex Physical coordination Sensory processing Notice: Judgment is last to develop !

Motivatio n Emotion Judgment Age 24 Physical coordination, sensory processing Ahh… Balance, Finally!

Sensory and physical activities benefit from earlier “back of the brain” development Complex, judgment-demanding thinking are compromised by later “front of the brain” development Implications of Arrested Development for Adolescent Behavior

We can infer...…. Preference for sensation seeking and physical activity Poor planning and judgment Minimal consideration of negative consequences More risky, impulsive behaviors Some evidence that being in a group accentuates impulsiveness Implications of Arrested Development for Adolescent Behavior

Research Question Addressed in the Literature: Are adolescents more susceptible than adults to alcohol? 4 lines of evidence Implications of Arrested Development for Drug Abuse Vulnerability

1. Evidence from epidemiological studies Implications of Arrested Development for Drug Abuse Vulnerability

Percentages of Past Year Alcohol Dependence or Abuse Among Adults Aged 21 or Older, by Age of First Use (SAMHSA, 2004) Age Started Drinking % Fewer Problems in Those Who Start Later

Alcohol Use Disorder in the Past Year by Age Group (SAMHSA, 2004) percent dependent or abusing past year

Binge Alcohol Use in the Past Month by Age Group (SAMHSA, 2004) percent binge use past month Binge = 5+ drinks same occasion on at least one day in the past 30 days.

Research Question Addressed in the Literature: Are adolescents more susceptible than adults to alcohol? Evidence from the laboratory Direct evidence can not obtained from human adolescents for ethical reasons. Much of what is known from adolescent rat studies. Implications of Arrested Development for Drug Abuse Vulnerability

Are adolescents more susceptible to alcohol than adults? 1. Epidemiological data Comparing adolescent and adult rats, both having no prior exposure to alcohol and matched on temperament…. 2. Adolescent rats are less sensitive to the sedative and motor impairment effects of intoxication. more drinking before “signals to stop”

Are adolescents more susceptible to alcohol than adults? 1. Epidemiological data 2. Adolescent rats are less sensitive to the sedative and motor impairment effects of intoxication. 3. Adolescent rats are more sensitive to the social disinhibition effects of alcohol. greater social comfort from intoxication

Are adolescents more susceptible to alcohol than adults? 1. Epidemiological data 2. Adolescent rats are less sensitive to the sedative and motor impairment effects of intoxication. 3. Adolescent rats are more sensitive to the social disinhibition effects of alcohol. #2 and #3 : May contribute to binge drinking and increased risk to alcohol dependence.

Are adolescents more susceptible to alcohol than adults? 1. Epidemiological evidence 2. Adolescent rats are less sensitive to the sedative and motor impairment effects of intoxication. 3. Adolescent rats are more sensitive to the social disinhibition effects of alcohol. 4. Alcohol may produce cognitive disruptions in adolescents.

4. Human Data: Alcohol’s Effects Adolescents with a history of extensive use…. Hippocampus volume (10%) brain activity during memory tasks converts informatio n to memory (Brown, 2002; Wuethrich, 2001) Not known if restoration or recovery will occur.

Evidence in support that youth are highly vulnerable to the effects of alcohol 1. Greater rates of alcohol dependence 2. Reduced sensitivity to intoxication 3. Increased social disinhibition 4. Increased cognitive disruption SUMMARY

INDIRECT evidence in support that youth are highly vulnerable to the effects of alcohol Neurodevelopment likely contributes to…. Risky, impulsive behavior Planning and judgment Ability to weigh consequences SUMMARY

Expect impulsivity, poor judgment, emotionality “On second thought…” NOT in the repertoire Parents must use THEIR judgment to protect teens Parents must anticipate - kids can’t Drugs, particularly alcohol, have different and more significant effects on teens Drug experimentation is normal BUT… can be dangerous

Take Home Summary P = Promote activities that capitalize on the strengths of the developing brain A = Assist children with challenges that require planning R = Reinforce their seeking advice from adults E = Educate about risk taking and negative consequences N = Never underestimate the effects of alcohol on the developing brain T = Tolerate the “oops” behaviors due to an immature brain

POLICY IMPLICATIONS Support services and programs that promote youth assets with neurodevelopment in mind structure adult supervision recreation, music, realistic cognitive challenges Re-visit age of majority/privilege? 16 - emancipation 16 - driving 18 - gambling (some states/some games) 18 - smoking

THANK YOU! web:

Suggested Readings Dubuc, B. (2004). The brain from top to bottom Leshner A. (2000). Oops. How casual drug use leads to addiction. National Institute on Drug Abuse, September, 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