Transcript Slide 1
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 Abstinence
Education Debated”
Objectives
Describe changes in brain structure and function that
occur during adolescence
Discuss 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.
is
A. AIDS
B. cancer
C. homicide
D. suicide
E. 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
Homicide
6,378
48.2
29.7
2,065
15.6
9.6
Suicide
1,452
11.0
6.8
Malignancy
638
4.8
3.0
Heron 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
-
-
-
63.2
62.3
58.1
57.5
55.1
56.5
71.0
68.8
64.4
64.2
62.5
53.7
50.0
46.2
43.6
Been drunk
Cigarettes
http://monitoringthefuture.org/
Adolescence
Physical Development (Puberty)
Early
Adolescence
Middle
Adolescence
Late
Adolescence
Social and Emotional Maturation
10 – 13 years
14 – 16 years
Cognitive Development
17 – 21 years
Social and Emotional Maturation
Emotional separation from parents
Develop a sense of personal identity and self-image
Identify with a peer group
Explore romantic relationships
Hazen E, et al. Pediatr Rev 2008;29:161-168
Cognitive Development
Increased ability to think abstractly
Greater impulse control
Improved ability to assess risk vs. reward
Improved use of working memory (the information in
memory available for working on a problem)
Cognitive alterations are associated with
changes in brain structure and function
Hazen E, et al. Pediatr Rev 2008;29:161-168
Casey BJ. Ann NY Acad Sci 2008;1124:111-126
Neuroanatomy Review
Gray matter (cerebral cortex):
Contains nerve cell bodies
Processes and routes information
Increases 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 Anatomy
Each new experience results in
new connections between
neurons
By the end of adolescence, the
brain contains
10 - 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 to
Prevent Teen Pregnancy; 2005.
Changes in Brain Anatomy
Pruning
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
Cells and connections are lost
if not used (facilitating more
efficient and faster information
processing)
Cells and connections
increase to provide
opportunities for
leaning and memory
Gogtay N, et al. PNAS 2004;101:8174-8179
http://www.pnas.org/content/suppl/2004/05/1
3/0402680101.DC1/02680Movie1.mpg
Brain Development and Risk Taking
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 groups
Substance use
Reckless driving
Crimes
Are adolescents more susceptible to the influences of
risk-prone peers?
Risky Business – The Role of Peers
Risky decision-making
asessed in:
106 adolescents (13-16 yrs)
105 youths (18-22 yrs)
95 adults (>24 yrs)
Decision-making assessed
using video game
Alone
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 Scale
5 hypothetical scenarios
Having sex without a condom
Riding in a car driven by someone who has been
drinking
Trying a new drug one knows nothing about
Breaking into store to steal something one wants
Driving 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 Peers
Younger 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 Activity
Nucleus 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
Measures hemodynamic
response (i.e., change in
blood flow) related to
neural activity
Risk-Reward and Brain Activity
Functional MRI performed during
tasks weighing risk and reward
Adolescents activate the nucleus
accumbens more than adults
Nucleus 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
Galvan A, et al. J Neurosci 2006;26:6885-6892
Galvan A, et al. Dev Sci 2007;10:F8-F14
C
Ad
A
Substance Use and the Brain
Limbic system - prefrontal
cortex connections grow into
early adulthood.
Certain of these neurons use
dopamine to relay messages
These 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
Non-smoker
Light smoker
(2-5 cigarettes/
day)
Rubinstein ML. Pediatr News 2010;44:28 (Sept. 2010)
“Hot” and “Cold” Cognition
“Hot” cognition
Decision made in an emotionally-charged situation
Adolescent surrounded by peers in a stimulating
environment may make an emotionally-based decision
“Cold” cognition
Decision made in a calmer, quieter environment
Adolescent may make a more intellectual, consequencebased decision
Social skills training (i.e., role-playing) may be
beneficial in moderating “hot” cognitions.
Recognizing Emotions
Adolescents often misinterpret body language and
words that are spoken
A 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 Emotions
Complex network of brain
regions involved in
recognizing
Basic emotions (fear)
Social emotions (guilt,
embarrassment, shame)
Network includes:
Amygdala
Medial prefrontal cortex
Anterior insula
Superior temporal sulcus
Blakemore S-J. Nat Rev Neurosci
2008;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
face
All adults correctly interpreted the
emotion as fear
Half of adolescents thought that
the woman expressed shock or
surprise
Blakemore 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 Emotions
19 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;21:1736-1750
Burnett S, Blakemore S-J. Ann NY Acad Sci 2008;1167:51-56
Processing Emotions
Adolescents activate
more of the medial
prefrontal cortex
Experiencing social
emotions is different
in adolescents
Perhaps adolescents
are still “working out”
social situations
Less efficient and
automatic
Burnett 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 Juvenile
Justice. Issue Brief 3: Less guilty by reason of adolescence. September 21, 2006
www.nytimes.com
Transition to Adulthood
Traditionally marked by:
Completing school
Leaving home
Becoming financially independent
Getting married
Having a child
Reaching milestones by age 30
1960: 77% of women, 65% of men
2000: fewer than half of women, 33% of men
Henig RM. nytimes.com. August 18, 2010
Conclusions
Adolescents see and react to the world differently than
children or adults
Late maturation of areas of the brain responsible for
complex thought processes helps explain
Delayed psychosocial maturation
Adolescent 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
Implications
Health promotion
Public policy
Tobacco Use
19.5% 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 Use
Standard approach:
Advise adolescent of
adverse effects of
tobacco use
Developmentally
appropriate approach:
Parental supervision
Policy making:
Prohibiting sale of tobacco
to minors
Prohibit tobacco
advertising
Prohibit tobacco use on
school grounds (students,
staff, parents)
Preventing Tobacco Use
3834 youths 12-17 years interviewed 3 times over a
4-year period
Odds of progressing from experimentation to
established smoking reduced by 40% in towns
with strong restaurant smoking regulations
9.6% 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 smoking
Siegal M, et al. Arch Pediatr Adolesc Med 2008;162:477-483
Brain Development and Policy
Roper 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
Caveats
Don’t over-interpret or over-simplify the information
The field is relatively young and growing at a rapid
pace
PubMed search of “brain development” and
“adolescence” yields 6,666 papers (11/20/09)
Conclusions
Adolescents see and react to the world differently than
children or adults
Changes in brain structure and function occur during
adolescence and likely impact behavior