Daniel Krowchuk, M.D.Departments of Pediatrics and Dermatology

Wake Forest University School of Medicine

November 15, 2009

“STD Cases Up Among Mississippi Teens”- Youths 15-19 comprise 7.6% of the state’s population- In 2008, they accounted for: 40.1% of chlamydia cases 32.3% of gonorrhea cases

“Merits of AbstinenceEducation Debated”

ObjectivesDescribe changes in brain structure and

function that occur during adolescenceDiscuss the implications of these changes

with respect to adolescent behavior and health promotion strategies

The leading cause of death for teenagers in the U.S. isA. AIDSB. cancerC. homicideD. suicideE. unintentional injury

Deaths, Percent of Total Mortality, and Death Rates by Cause, 15-19 year olds, U.S., 2007

Cause Number

Percent

Rate/100,000

All Causes 13,235 100.0 61.6

Unintentional injury

6,378 48.2 29.7

Homicide 2,065 15.6 9.6

Suicide 1,452 11.0 6.8

Malignancy 638 4.8 3.0Heron M, et al. Pediatrics 2010;125:4-15 (data from National Vital Statistics System: mortality 2007, www.cdc.gov/nchs/nvss/mortality_tables.htm )

What percent of high school seniors report having been drunk?A. 25%B. 40%C. 55%D. 70%E. 85%

Lifetime Prevalence of Use (%) of Various Substances by High School Seniors

Substance

1980

1985

1990

1995

2000

2003

2005

2007

2009

Any illicit drug

65.4 60.6

47.9

48.4

54.0 51.1

50.4 46.8 46.7

Marijuana

60.3 54.2

40.7

41.7

48.8 46.1

44.8 41.8 42.0

LSD 9.3 7.5 8.7 11.7

11.1 5.9 3.5 3.4 3.1

Ecstasy - - - - 11.0 8.3 5.4 6.5 6.5

Cocaine 15.7 17.3

9.4 6.0 8.6 7.7 8.0 7.8 6.0

Been drunk

- - - 63.2

62.3 58.1

57.5 55.1 56.5

Cigarettes

71.0 68.8

64.4

64.2

62.5 53.7

50.0 46.2 43.6

http://monitoringthefuture.org/

Physical Development (Puberty)

Social and Emotional Maturation

Cognitive Development

Early Adolescence

Middle Adolescence

Late Adolescence

10 – 13 years 14 – 16 years 17 – 21 years

Social and Emotional MaturationEmotional separation from parentsDevelop a sense of personal identity and self-

imageIdentify with a peer groupExplore romantic relationships

Hazen E, et al. Pediatr Rev 2008;29:161-168

Cognitive DevelopmentIncreased ability to think abstractlyGreater impulse controlImproved ability to assess risk vs. rewardImproved use of working memory (the

information in memory available for working on a problem)

Hazen E, et al. Pediatr Rev 2008;29:161-168Casey BJ. Ann NY Acad Sci 2008;1124:111-126

Cognitive alterations are associated with

changes in brain structure and function

Neuroanatomy ReviewGray matter (cerebral cortex):

Contains nerve cell bodiesProcesses and routes informationIncreases in pre-adolescence then

decreases

White matter:Composed of nerve cell extensions (axons) that convey

information (e.g., from gray matter)Color results from myelin coating of axons (acts as

insulation that allows nerve impulses to travel more rapidly and efficiently)

Changes in Brain AnatomyEach new experience

results in new connections between neurons

By the end of adolescence, the brain contains10 - 100 billion neurons

Forming 100 trillion connections with one another

100 billion – 1 trillion support cells

Increased intelligence, reasoning, problem-solving

Weinberger DR, et al. The Adolescent Brain:A Work in Progress. National Campaign toPrevent Teen Pregnancy; 2005.

Changes in Brain AnatomyPruning

Information that is used regularly is retained – that which is unimportant or used infrequently is lost as the result of pruning (a loss of cells or connections) Adolescents may lose 15% of synaptic connections/year

(compared with 1-2% for adults) Results in greater efficiency

Myelination Fatty covering of axons that acts as insulation

Permits more rapid (100-fold) and efficient communication

Increases into the third decade

Weinberger DR, et al. The Adolescent Brain: A Work in Progress.National Campaign to Prevent Teen Pregnancy; 2005.

Cortical Development

Gogtay N, et al. PNAS 2004;101:8174-8179

Cells and connectionsincrease to provide opportunities for leaning and memory

Cells and connections are lostif not used (facilitating more efficient and faster informationprocessing)

http://www.pnas.org/content/suppl/2004/05/13/0402680101.DC1/02680Movie1.mpg

Lateral prefrontal cortex(Cognitive control)-Impulse control-Setting priorities-Formulating plans-Decision-making-Envisioning consequences of actions

Limbic system(Socioemotional)-Impulsiveness-Sensation-seeking

Risky Business – The Role of Peers Among adolescents, many high risk behaviors

take place in groupsSubstance useReckless drivingCrimes

Are adolescents more susceptible to the influences of risk-prone peers?

Risky Business – The Role of PeersRisky decision-making

asessed in:106 adolescents (13-16

yrs)105 youths (18-22 yrs)95 adults (>24 yrs)

Decision-making assessed using video gameAlone In group with 2 other

subjects who could offer advice

- Watch car move across screen until yellow traffic light appears- Stop car before red light and wall appear- More points the further the car moved without crashing into wall

Gardner M, Steinberg L. Dev Psychol 2005;41:625-635

Risk Preference Scale5 hypothetical scenarios

Having sex without a condomRiding in a car driven by someone who has

been drinkingTrying a new drug one knows nothing aboutBreaking into store to steal something one

wantsDriving over 90 mph on highway at night

Ranked 1 (risks are much greater than benefits) to 4 (benefits are much greater than risks)

Gardner M, Steinberg L. Dev Psychol 2005;41:625-635

Risky Business – The Role of PeersYounger

individuals: Allowed car to move

further after yellow light

Chose riskier course of action on questionnaire

Were more likely to be affected by peer influences

Gardner M, Steinberg L. Dev Psychol 2005;41:625-635

Risk-Reward and Brain ActivityNucleus accumbens

Component of the limbic system

Involved in processing rewards Cortex receives stimulus

indicating reward Nucleus accumbens and other

areas are activated leading to repetition of the gratifying behavior

Develops earlier than the prefrontal cortex

Galvan A, et al. J Neurosci 2006;26:6885-6892

Risk-Reward and Brain ActivityFunctional MRI performed

during tasks weighing risk and rewardAdolescents activate the nucleus

accumbens more than adultsNucleus accumbens activity

correlates with anticipation of a positive consequence of a risky behavior (which, in turn, correlates with the likelihood of engaging in risky behaviors) – more pronounced in adolescents

C Ad A

Galvan A, et al. J Neurosci 2006;26:6885-6892Galvan A, et al. Dev Sci 2007;10:F8-F14

Measures hemodynamic response (i.e., change in blood flow) related to neural activity

Substance Use and the BrainLimbic system - prefrontal

cortex connections grow into early adulthood.

Certain of these neurons use dopamine to relay messagesThese neurons increase

capacity for more mature thought (choices based on memory not impulse)

Cocaine and amphetamines target these dopaminergic neurons.

Weinberger DR, et al. The Adolescent Brain: A Work in Progress. National Campaign to Prevent Teen Pregnancy; 2005.

Nicotine and Addiction Centers

Rubinstein ML. Pediatr News 2010;44:28 (Sept. 2010)

Non-smoker

Light smoker(2-5 cigarettes/day)

“Hot” and “Cold” Cognition“Hot” cognition

Decision made in an emotionally-charged situationAdolescent surrounded by peers in a stimulating

environment may make an emotionally-based decision

“Cold” cognitionDecision made in a calmer, quieter environmentAdolescent may make a more intellectual,

consequence-based decisionSocial skills training (i.e., role-playing) may be

beneficial in moderating “hot” cognitions.

Recognizing EmotionsAdolescents often misinterpret body

language and words that are spokenA parent stares at their adolescent waiting for

a response to a question – the adolescent interprets the stare as the parent being angry.

An adolescent looks across the lunchroom at an acquaintance; the acquaintance happens to turn her head in the other direction – the adolescent may interpret that she has been shunned.

Adapted from Feinstein S. Secrets of the Teenage Brain. Thousand Oaks, Ca: Corwin Press; 2004

Recognizing EmotionsComplex network of

brain regions involved in recognizing Basic emotions (fear)Social emotions (guilt,

embarrassment, shame)Network includes:

AmygdalaMedial prefrontal cortexAnterior insulaSuperior temporal

sulcus

Blakemore S-J. Nat Rev Neurosci2008;9:267-276

Do Adolescent and Adults Differ?Adults and adolescents

presented with the photograph of a woman with an expression of fear on her faceAll adults correctly

interpreted the emotion as fear

Half of adolescents thought that the woman expressed shock or surpriseBlakemore S-J. Nat Rev Neurosci

2008;9:267-276

Ekman P, Friesen WV.Pictures of Facial Affect. Palo Alto, CA: Consulting Psychologists Press; 1976

Processing Emotions19 adolescents (10 - 18 years) and 10 adults

(22 – 32 years) underwent functional MRI scanning1 while thinking about scenarios involving:Basic emotions (e.g., disgust, fear)Social emotions (e.g., embarrassment, guilt,

shame) Requires awareness on your part of others’ opinions

of your action

Burnett S, et al. J Cogn Neurosci 2009;21:1736-1750Burnett S, Blakemore S-J. Ann NY Acad Sci 2008;1167:51-56

Processing EmotionsAdolescents

activate more of the medial prefrontal cortex

Experiencing social emotions is different in adolescentsPerhaps adolescents

are still “working out” social situations

Less efficient and automaticBurnett S, et al. J Cogn Neurosci 2009;21:1736-1750

Burnett S, Blakemore S-J. Ann NY Acad Sci 2008;1167:51-56

How Not to Embarrass a Teen1

Don’t correct or reprimand her in front of others.

Don’t fix his clothes, straighten his tie, or tuck in his shirt in public.

Don’t call her by a pet nickname in front of her friends.

Don’t kiss, hug, or show affection on school grounds.

Don’t run into the middle of class to bring something he’s forgotten.

1Elias Z, Goldman T. How Not to Embarrass Your Kids: 250 Don’ts for Parents of Teens.New York, NY: Warner Books; 2009

Conclusions

MacArthur Foundation Research Network on Adolescent Development and JuvenileJustice. Issue Brief 3: Less guilty by reason of adolescence. September 21, 2006

www.nytimes.com

Transition to AdulthoodTraditionally marked by:

Completing schoolLeaving homeBecoming financially independentGetting marriedHaving a child

Reaching milestones by age 301960: 77% of women, 65% of men2000: fewer than half of women, 33% of men

Henig RM. nytimes.com. August 18, 2010

ConclusionsAdolescents see and react to the world

differently than children or adultsLate maturation of areas of the brain responsible

for complex thought processes helps explain Delayed psychosocial maturationAdolescent behavior (including involvement in

risky endeavors)Adolescents need supportive parents, adults, and

institutions that provide guidance and help them learn appropriate skills and adult behaviors

ImplicationsHealth promotionPublic policy

Tobacco Use19.5% of high school students are current

smokers (>1 time in past 30 days) and 7.3% use cigarettes frequently (>20 of 30 days/month)1

Half of the 3000 adolescents who begin smoking each day will become daily smokers2

90% of adult smokers began smoking as adolescents2

1Centers for Disease Control and Prevention. Youth Risk Behavior Surveillance. (2009) http://www.cdc.gov/HealthyYouth/yrbs/index.htm 2Ziedonis D, et al. Adolesc Med Clin 2006;17:381-410

Preventing Tobacco UseStandard approach:

Advise adolescent of adverse effects of tobacco use

Developmentally appropriate approach:Parental supervisionPolicy making:

Prohibiting sale of tobacco to minors

Prohibit tobacco advertising

Prohibit tobacco use on school grounds (students, staff, parents)

Preventing Tobacco Use3834 youths 12-17 years interviewed 3 times

over a 4-year periodOdds of progressing from experimentation

to established smoking reduced by 40% in towns with strong restaurant smoking regulations9.6% risk in towns with weak regulations vs. 7.9%

for towns with strong regulations Rationale:

Reduce youths’ exposure to tobacco in public places (lowers perception of smoking prevalence)

Change perceived social acceptability of smokingSiegal M, et al. Arch Pediatr Adolesc Med 2008;162:477-483

Brain Development and PolicyRoper v. Simmons (2005, US Supreme Court)

17-year-old convicted of murder and sentenced to death American Psychological Association (APA) and AMA filed

briefs arguing that adolescents’ still developing brains made them different than adults. Death penalty was outlawed if offender <18 years of age when crime committed.

Hodgson v. Minnesota (1990, US Supreme Court)Case challenged Minnesota law requiring parental

consent for abortion. The APA argued that by age 14 or 15 years, adolescent decision making was essentially equivalent to that of an adult.

Johnson SB, et al. J Adolesc Health 2009;45:216-221

CaveatsDon’t over-interpret or over-simplify the

informationThe field is relatively young and growing at a

rapid pacePubMed search of “brain development” and

“adolescence” yields 6,666 papers (11/20/09)

ConclusionsAdolescents see and react to the world

differently than children or adultsChanges in brain structure and function

occur during adolescence and likely impact behavior