daniel krowchuk, m.d. departments of pediatrics and dermatology wake forest university school of...
Post on 28-Mar-2015
216 Views
Preview:
TRANSCRIPT
Daniel Krowchuk, M.D.Departments of Pediatrics and Dermatology
Wake Forest University School of Medicine
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., 2004
Cause Number
Percent
Rate/100,000
All Causes 13,706 100.0 66.1
Unintentional injury
6,825 49.8 32.9
Homicide 1.932 14.1 9.3
Suicide 1,700 12.4 8.2
Malignancy 731 5.3 3.5
Heron M. National Vital Statistics Reports 2007;56(5)
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
2006
2007
2008
Any illicit drug
65.4 60.6
47.9
48.4
54.0 51.1
48.2 46.8 47.4
Marijuana
60.3 54.2
40.7
41.7
48.8 46.1
42.3 41.8 42.6
LSD 9.3 7.5 8.7 11.7
11.1 5.9 3.3 3.4 4.0
Ecstasy - - - - 11.0 8.3 6.5 6.5 6.2
Cocaine 15.7 17.3
9.4 6.0 8.6 7.7 8.5 7.8 7.2
Been drunk
- - - 63.2
62.3 58.1
56.4 55.1 54.7
Cigarettes
71.0 68.8
64.4
64.2
62.5 53.7
47.1 47.1 44.7
http://monitoringthefuture.org/ (1/09)
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 other100 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 AnatomyPruning
Information that is regularly used 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.
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 lightChose riskier course of action on
questionnaireWere 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 systemInvolved 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
Ad
Galvan A, et al. J Neurosci 2006;26:6885-6892Galvan A, et al. Dev Sci 2007;10:F8-F14
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.
“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 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 faceAll adults correctly interpreted the
emotion as fearHalf of adolescents thought that the
woman expressed shock or surprise
Blakemore S-J. Nat Rev Neurosci 2008;9:267-276
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 cortexExperiencing social emotions is different
in adolescentsPerhaps adolescents are still “working out”
social situationsLess efficient and automatic
Burnett S, et al. J Cogn Neurosci 2009;21:1736-1750Burnett 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
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 Use9.4% of high school students 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. http://www.cdc.gov/mmwr/PDF/SS/SS5505.pdf2Ziedonis 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
top related