1. Navigating the Teen Years: Travel Inside the Adolescent Brain
Ken Winters, Ph.D.
Department of Psychiatry
University of Minnesota
Drug Free Communities – Waukesha County
Waukesha, WI
September 26, 2013 1

2. Teen Brain Development Resources & Summary Keys to Parenting
and early drug use
Keys to
Parenting

3. Teen
Brain Development

4. 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 25!!!

5. Important ages of majority and privileges
16 - emancipation
- driving
18 - gambling (usually age 21 when alcohol served)
- smoking (some at age 19
- military
21 -drinking

6. An Immature Brain = More Accelerator, Less Brakes

7. Maturation Occurs from Back to Front of the Brain
Images of Brain Development in Healthy Youth (Ages 5 – 20)
Blue represents maturing of brain areas
Source: PHAS USA 2004 May 25; 101(21): Epub 2004 May 17.

8. Brain Development RATE OF CHANGE Volume Adolescence Myelination
Metabolism
Blood Flow
Receptors
Adolescence
Myelination
Although most of the brain material and size is in place at the start of adolescence, several important developmental processes continue .
If all goes well, the brain will be a much more efficient organ at the end of a healthy adolescence.
One process is myelination. The axons connecting brain cells across which electrical impulses travel continue to become ensheathed in a fatty substance called myelin. This compound insulates axons and speeds the relay of electric impulses within the brain, helping thinking, decision-making, impulse control, and emotional regulation mature.
Another process is synaptic refinement. At the start of adolescence, we have billions of brain cells, each with tens of thousands of connections to other brain cells. Not all these connections are actually needed, and the unnecessary ones become eliminated. This elimination process is shaped by the young person’s activities and experiences, and, as with myelination, it helps the brain work more efficiently.
MRI studies reveal ongoing brain maturation during late childhood and early adulthood. Early MRI studies suggest regionally varying volume decreases in gray matter of the cortex and subcortical nuclei (Jernigan, Tallal). More recent studies provide more anatomical detail, emphasize the effects of ongoing myelination and employ mapping methods for visualizing the pattern of age-related change (Sowell, Jernigan). Of particular interest are reported changes between adolescence and young adulthood. A voxel-based comparison of gray matter distribution between two groups of normal young people with mean ages of 14 and 26 showed substantial striatum and thalamus volume reduction, and frontal cortex thinning concurrently with continuing myelination of the underlying white matter in this region. Normal age-effects for volumes of particular brain structures (Jernigan & Gamst, 2005) indicate protracted age-related increases in cerebral white matter, associated with ongoing myelination, as well as volume reductions in nucleus accumbens and thalamus, and continuing volume increase (in young adults) in hippocampal volume.
Recently, the ongoing white matter development revealed in these morphometry studies has been studied more closely with DTI. DTI studies focusing specifically on the adolescent age range all show increases in FA in distributed subcortical regions between childhood and young adulthood. Although FA values are lower than in white matter, some of the most robust increases in FA observed across the adolescent age range were in these structures, perhaps reflecting maturation of internal fiber tracts. These FA changes are likely related to the steep reductions in striatal and thalamic gray matter volumes shown in the graphics above. Exposure to alcohol and other drugs during adolescence may alter the function of frontal-striatal and limbic circuits to interact with this pattern of ongoing brain maturation during late adolescence and early adulthood.
Synaptic Refinement 1 2 7 16 30
Prenatal
Post-birth Age
Tapert & Schweinsburg (2005)

9. Preference for …. Less than optimal.. Greater tendency to…
Implications of Brain Development for Adolescent Behavior
Preference for ….
physical activity
high excitement and rewarding activities
activities with peers that trigger high intensity/arousal
novelty
Less than optimal..
control of emotional arousal
consideration of negative conseq.
Greater tendency to…
be attentive to social information
take risks and show impulsiveness

10. reward incentives > perception of consequences
Implications of Brain Development for Adolescent Behavior
reward incentives >
perception of consequences

11. It’s easy to remember the main functions of the limbic system by thinking of the four Fs.11

12. Teen Brain Development
and early drug use

14. The teen brain may be more
sensitive to the acute
effects of drugs on the
dopamine system

16. Prevalence of Past-Year DSM-IV Alcohol Dependence: United States, (Grant, B.F., et al., Drug and Alcohol Dependence, 74, , 2004) %

17. 10% smaller volume MRI: Hippocampal Size Hippocampus Encodes new info
Left smaller in AUD teens (p<.01)
But no relationship with cognitive functioning (due to less severe alcohol group than Brown et al. sample?)
hippocampus
This picture of the brain depicts the prefrontal regions, critical to planning, organizing information, inhibiting impulses, and regulating emotions.
We also see the hippocampus, a structure essential to learning and forming new memories, which is located deeper within the brain (we all have 2: one on the left and one on the right). It too is continuing to develop during adolescence.
Studies with rodents have suggested that the hippocampus is particularly sensitive to alcohol, especially during adolescence.
This image of the brain is taken face-on, at a slice near the ear.
De Bellis and colleagues found smaller left and right hpc volumes in AUD adolescents & young adults. We wanted to extend these findings by comparing AUD with yery limited psych como and other substance use with controls.
We replicated study by De Bellis et al., 2001 which found smaller hippcampi in adol & young adults with AUD, but sample included other drug use disorders, PTSD, and other psychiatric disorders. Here, we exclude for other substance use disorders and all other psych disorders except CD
Since we previously found learning and memory difficulties in alcohol abusing teens, we looked at the volume a structure critical to memory formation – the hippocampus.
14 adolescents (ages 15 to 17 years) with AUD and 17 healthy comparison teens, all free from psychiatric problems.
Those with histories of heavy drinking had smaller left HC volume, even after controlling for conduct disorder.
Nagel, Schweinsburg, Pham, & Tapert, 2005

18. 2013 US Marijuana Laws by State

19. What’s Affected by Marijuana?
So, what all is affected by marijuana?

20. Perhaps the most worrisome is the finding in a number of recent studies that tracked people from childhood to adulthood, that those who smoked marijuana regularly and heavily during adolescence and continuing into adulthood had a higher risk of developing mental illness...

21. Prevalence of Past Year Serious Mental Illness Among Lifetime Marijuana Users Aged 18+ (SAMHSA, 2005; data collected )
percentages
age of marijuana onset

22. Significant drop in IQ for early and chronic users
Meier et al., 2012; PNAS

23. Allstate ad, NY Times,
May, 2007

24. Driving a car with a distracted and inexperienced teenager behind the wheel24

25. Impact of Peer Presence on Risky Driving in Simulated Context
peer effect
Chein et al., in press 25

26. Teen Brain Development Keys to Parenting
and early drug use
Keys to
Parenting

27. Striking the Right Balance
MONITORING
+ - +
SUPPORT -
< desired
desired
< desired
worse

28. Effective Parenting Component #4: Monitoring and Supervision28

29. The Developing Brain, Adolescence and Vulnerability to Drug Abuse
Key Protective Factors that Improve the Likelihood of a Drug-Free Child
Many opportunities for conventional involvement, positive family involvement
Good impulse control
Follows rules and avoids delinquent peers
Negative attitudes toward drugs
Low availability of drugs
High commitment to school
High perceived risk of drug use
Rewarded for involvement in conventional activities
Family attitudes do not favor drug use
Family is close
Copyright © 2008 The Mentor Foundation
Slide 29

30. Which ones are the easiest for a parent to influence? Toughest?
The Developing Brain, Adolescence and Vulnerability to Drug Abuse
Which ones are the easiest for a parent to influence? Toughest?
Many opportunities for conventional involvement, positive family involvement
Good impulse control
Follows rules and avoids delinquent peers
Negative attitudes toward drugs
Low availability of drugs
High commitment to school
High perceived risk of drug use
Rewarded for involvement in conventional activities
Family attitudes do not favor drug use
Family is close
Copyright © 2008 The Mentor Foundation
Slide 30

31. Assist your child with challenges that require planning
Take Home for Parents
Promote activities that capitalize on the strengths of the developing brain
Assist your child with challenges that require planning
Reinforce their seeking advice from you and other adults
Encourage lifestyle that promotes healthy brain development
Never underestimate drug effects on developing brain
Tolerate “oops” behaviors common during the teens 31

32. Teen Brain Development Resources & Summary Keys to Parenting
and early drug use
Keys to
Parenting

35. 1. Prevention Smart Parents www. prevention-smart.org

36. 2. The Partnership www.drugfree.org
Helps parents prevent, intervene in and find treatment for drug and alcohol use by their children

38. Summary
Adolescence is an extended period of transition from reliance on adults to independence
Normal adolescence is characterized by….
increase in conflicts with family members
desire to be with one’s friends
resistance to messages from authority
irritability
proclamations of sheer boredom
risk taking
reward incentive-biased decision making

39. Gray Matter Maturation, Age 4-21
Summary
The brain undergoes a considerable amount of development during the teen years.
The last area to mature is the prefrontal cortex region; involved in planning, decision making and impulse control.
Gray Matter Maturation, Age 4-21
Gogtay et al., 2004

40. Summary reward incentives > perception of consequences
Gray Matter Maturation, Age 4-21
Gogtay et al., 2004
reward incentives > perception of consequences

41. Stay involved as a parent41

42. THANK YOU! winte001@umn.edu