ADOLESCENT BRAIN DEVELOPMENT: A PERIOD OF VULNERABILITIES

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ADOLESCENT BRAIN DEVELOPMENT A PERIOD OF
VULNERABILITIES OPPORTUNITIES Ronald E Dahl,
M.D.Staunton Professor of Psychiatry and
Pediatrics University of Pittsburgh
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High-Stakes Issues The Health Paradox of
Adolescence

• Adolescence is (physically) the healthiest period
  of the lifespan prior to adult declines
  beyond the frailties of infancy and
  childhood
• Improvements in strength, speed, reaction time,
  reasoning abilities, immune function
• Increased resistance to cold, heat, hunger,
  dehydration, and most types of injury
• Yet overall morbidity and mortality rates
  increase 200 from childhood to late adolescence

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Morbidity Mortality in Adolescence

• Primary sources of death/disability are related
  to problems with control of behavior and emotion
• Increasing rates of accidents, suicide, homicide,
  depression, alcohol substance use, violence,
  reckless behaviors, eating disorders, health
  problems related to risky sexual behaviors
• High rates of risk-taking, sensation-seeking, and
  erratic (emotionally-influenced) decisions
• Behavior with long-term health consequences

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Probability of Smoking Initiation

• Onset of alcohol and other substances
• Onset of initial depression episode
• More than 50 of HIV risk
• Rates of accidents related to violence and
  reckless behavior

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Alcohol Use by Age
Source SAMHSA National Survey on Drug Use and
Health 2003
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Marijuana Use and Adolescence
Early initiation gt95 of users begin lt 25 years
old Discontinuation 75 stop regular use by
early 30s
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Adolescence as a Developmental Period of Unique
Risks ( Opportunities)

• Gene/Environment/Development interactions
• Reward Neurocircuitry
• changes at puberty?
• emotional and motivational influences on decision
  making?
• Adolescence as a crucial time for developing
  self-regulatory capacities (decision-making
  skills)

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Overview of General Model

• Early adolescence as a period of brain
  development that creates unique vulnerabilities
  (and opportunities) for some kinds of
  emotional-motivational learning.
• Onset of puberty Activational effects on drives,
  motivation, and emotions
• Versus gradual emergence of cognitive control
• Relevance of Earlier timing of puberty
• Scaffolding/social support
• Social policy and intervention

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Tipping Points and Spirals in Development?
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Puberty The Balance of Adolescence

• PUBERTY rapid physical, endocrine, and affective
  changes (EARLY)
• Versus the gradual (LATE) development of affect
  regulation and maturation of cognitive/self-contro
  l skills (progress slowly and continue long after
  puberty is over)

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Adolescence

• Youth are heated by Nature
• as drunken men by wine.
• --Aristotle
• I would that there were no age between
• ten and twenty threefor there is nothing
• in between but getting wenches with child,
• wronging the ancientry, stealing, fighting
• --Shakespeare (The Winters Tale Act III)

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The Tinderbox in the Teen-age Brain

• As illustrated by Romeo and Juliet (and hundreds
  of other stories, dramas, and movies) adolescence
  has been recognized throughout human history as a
  time when surging emotions have a particularly
  dramatic capacity to influence decisions and
  behavior.

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Scientific Questions

• What is the empirical evidence that adolescents
  are heated by Nature?
• Role of biology? Specific hormones of puberty?
  Role of intensifying emotions?
• Specific neurobehavioral underpinnings to
  adolescent-onset motivational tendencies for
• risk-taking and/or sensation-seeking?
• status-seeking?
• emotional and motivational changes at puberty?

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Defining Adolescence Conceptual Issues
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Adolescence

• That awkward period between sexual maturation and
  the attainment of adult status in society.
• The transition from child status (requires some
  adult monitoring) to adult self-responsibility
  for ones behavior in the absence of adult
  supervision
• Interposed with physical and neurobehavioral
  changes of puberty

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Hormonal axes at puberty 1) Gonadarche
(gonadal maturation) 2) Rapid Physical Growth
involves a second (separate) cascade of
hormones GHRH GH IGFs 3) Adrenarche yet
another set of hormones rise in DHEA/S (weak
androgens that contribute to development of pubic
axillary hair acne)
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Some Aspects of Puberty Have Been Occurring
Earlier
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Herman-Giddens et al 199717,000 Girls in US
Pediatric Practices w Breast/Pubic Hair
Development at Tanner 2 or above
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The past 150 years have witnessed a quiet
revolution in human development that still sweeps
across the globe today children nearly
everywhere are growing faster, reaching
reproductive and physical maturity at earlier
ages, and achieving larger adult sizes than
perhaps ever in human history. --Carol M
Worthman, Ph.D. In an anthropological study of
adolescence in 185 different societies, Schlegel
and Barry found that the interval between
attaining puberty and taking on adult roles was
typically 2-4 years in the majority of
traditional societies studied.
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Puberty, Marriage, and Adult Roles in
Contemporary Society (United States)

• Average age of menarche is now age 12 average
  age of first marriage for females is 26.
• Not simply changing attitudes about marriage
• Many adult social rolesstarting careers, owning
  a home, choosing to become parentsare now
  occurring a decade or more after puberty.
• These changes have advantages and costs (create
  vulnerabilities).
• ADOLESCENCE HAS EXPANDED from a 2-4 year interval
  in traditional societies to an 8-15 year interval
  in contemporary society.

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Puberty Changes in Motivation/Emotion

• Strongest direct links to puberty changes in
  romantic motivation, sexual interest, emotional
  intensity, sleep/arousal regulation, appetite,
  and risk for affective disorders
• A general increase in risk taking, novelty
  seeking, sensation seeking (status seeking).
• Animal studies also show behavioral changes and
  alterations in social motivation in adolescent
  period (Spear 2000) many examples of
  species-specific changes (e.g. play fighting in
  rats takes on stakes Pellis 2004)

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Human Puberty Igniting Passions in the
Developing Brain

• Profound changes in romantic interest,
  motivation, emotional intensity
• Intensification of many types of goal-directed
  behavior, including intense motivation for
  long-term and abstract goals (particularly those
  related to social-status)
• Relatively understudied aspect of adolescent
  development (neurobehavioral changes in emotion
  and motivation)

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In contrast to these early affective changes
directly linked to puberty

• Most measures of cognitive development correlate
  with age and experience
• (not sexual maturation)
• planning, logic, reasoning, inhibitory control
  problem-solving skills capacity for
  understanding long-term consequences of behavior
• These maturational capacities continue to develop
  long after puberty is over
• Brain development?

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Brain Development into early adolescence in
longitudinal study by anatomic region ( Sowell et
al 2004)
Data from Giedd et al, Luna et al, Pine et al and
other showing structural and functional
maturation continuing into the early twenties
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Hypothesis regarding affective development
Starting the engines with an unskilled driver

• Earlier (historically) timing of puberty results
  in several years with a sexually-mature body and
  sexually-activated brain circuits (igniting
  passions)
• Yet with relatively immature neurobehavioral
  systems necessary for cognitive-control and
  affect regulation
• Predict increased risk for disorders of
  self-control difficulties navigating
  social-emotional situations

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AFFECTIVE LOAD
REGULATORY CONTROL
Influence of peers, media, music, etc.
Social stress and conflicts
Pubertal drives and emotions
Cognitive control self regulation
Social support
Family/parent/ adult monitoring
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AFFECTIVE LOAD
REGULATORY CONTROL
External controls on behavior diminish across
adolescence
Improvements occur slowly across adolescence
(relatively late)
These effects increase sharply at puberty
(relatively early effects)
Variable
Influence of peers, media, music, etc.
Social stress and conflicts
Pubertal drives and emotions
Cognitive control self regulation
Social support
Family/parent/ adult monitoring
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AFFECTIVE LOAD
REGULATORY CONTROL
External controls on behavior diminish across
adolescence
Improvements occur slowly across adolescence
(relatively late)
These effects increase sharply at puberty
(relatively early effects)
Variable
Influence of peers, media, music, etc.
Social stress and conflicts
Pubertal drives and emotions
Cognitive control self regulation
Social support
Family/parent/ adult monitoring
Cognitive-emotional interface?
Higher stakes status seeking? Social anxieties?
Cognitive skills for dealing with strong emotion?
Early Romantic Relationships?
Rumination?
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AFFECTIVE LOAD
REGULATORY CONTROL
External controls on behavior diminish across
adolescence
Improvements occur slowly across adolescence
(relatively late)
These effects increase sharply at puberty
(relatively early effects)
Variable
Influence of peers, media, music, etc.
Social stress and conflicts
Pubertal drives and emotions
Cognitive control self regulation
Social support
Family/parent/ adult monitoring
Genetic influences greater affective challenges
(e.g. SERT)
Genetic influences cognitive control/self
regulation?
Early Adversity/ Poor Foundation ?
Genetic influences impulsivity sensation
seeking
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Sleep/Arousal Regulation Example To Illustrate
Key FeaturesBrain/Behavior/Context Interactions

• Some developmental changes in sleep regulation
  are biologic and linked to puberty
• Some changes in sleep regulation linked to social
  environmental influences, habits, and patterns
• Spiraling interactions between these domains can
  lead to vulnerability and spiral into serious
  clinical problems

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Adolescent Sleep Pubertal Changes

• Shift in biologic timing systemsphysiologic
  change in tendency to prefer to stay up
  late/sleep-in late
• Related to changes in circadian system more
  owl-like tendencies
• Lee et al animal model in O. degus
• Pubertal increases in daytime sleepiness
• Probably an increase need for sleep during
  puberty and adolescence

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Social factors contributing to LATE
bedtimes/sleep onset times

• Peers and social activities
• Greater freedom to self-select bedtimes
• Access to light and stimulating activities
• Stress/anxiety or excitement ? difficulty falling
  asleep
• Major circadian shift on weekends/vacation
• Work, Sports, Homework, Projects, meds...

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The School-Sleep Squeeze

• Despite average school night bedtimes of 1130 pm
  in high school seniors, the average wake-up time
  on school days is 615 am.
• Greater than 10 of US high school students must
  get up before 530 am to catch buses
• More than 15 of high school students report
  averaging 6 or less hours of sleep per night on
  school days (need 8 or more)

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Consequences of Insufficient Sleep in Adolescents

• Sleepiness, Tiredness
• Difficulties with focused attention
• Irritability, Emotional lability
• Difficulties with affect regulation
  cognitive-emotional integration
• Direct effects on learning, memory consolidation
• Increase use of caffeine, stimulants

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A Small Biological Change Leading to a Spiral of
Negative Effects

• Late night/erratic schedules ?
• Sleep Deprivation
• ? erodes mood and motivation
• ? greater stress and affective problems
• ? interferes further w sleep/arousal
  regulation
• ? greater difficulty falling asleep
• Social context that amplifies the biologic change
  ? a descending spiral

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Analogous Spiral in Emotion Regulation/Cognitive
Control?

• Achieving a more mechanistic understanding of
  emotion regulation

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Negative spirals
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Yet, These Affective Changes in Adolescence May
Create Unique Maturational Opportunities

• Establishing new links between more complex ways
  of thinking and new emotional/motivational
  experiences
• Development of brain systems underpinning higher
  levels of cognitive-emotional integration
• Opportunities for early intervention/prevention
  in identified high-risk samples
• Igniting passions can be sculpted by positive
  learning experiences

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Brain/Behavior/Social-Context Interactions
Positive SPIRALS

• Igniting Passions
• Sports
• Literature/Arts/Music
• Science/Medicine
• Politics
• Caring for others
• Larger Purpose
• Changing the world in positive ways

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Conclusions

• Early adolescence appears to be a natural time of
  motivational learninga time of igniting passions
  in ways that create vulnerability for developing
  destructive versionsaddiction, reckless
  behavior, and emotional disorders. Yet, also
  opportunities to align these passions to healthy
  long-term goals.
• Compelling neuroscientific questions about
  mechanisms in ways that can inform early
  intervention in high-risk populations and to
  promote social policies that can contribute to
  healthy development in youth.

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THANK YOU