ADOLESCENT BRAIN DEVELOPMENT

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ADOLESCENT BRAIN DEVELOPMENT

• TIME OF TURMOIL AND TRIUMPH
• BARBARA SULLIVAN, Ph.D.
• September 14 and 15, 2009

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GOALS

• To increase participant understanding of
• the structures, functions, and stages of
  development of the brain
• how adolescence has changed over the last 150
  years
• the differences between adult and adolescent
  thinking
• the impact of abuse and neglect on the brain
• current trends in adolescent alcohol use
• the impact of alcohol use on the brain
• what clinicians, prevention specialists, and
  communities can do to support healthy
  adolescent development

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CAVEATS

• New discoveries research is still in its
  infancy
• Do NOT over-interpret or interpret too
  simplistically
• Research is not to the point that it can inform
  causal models
• Most research has been conducted on male animals
  we assume the information transfers to people
• Behavior is the result of complex interactions
  among individual, environment, genetics,
  situation, cultural expectations, and numerous
  other factors

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• BRAIN STRUCTURES AND FUNCTIONS

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BRAIN FACTS

• Brain weighs approximately 3 pounds
• Brain has approximately 100 billion neurons and 1
  trillion supporting cells
• Neurons grow and organize themselves into
  efficient systems that operate a lifetime

• Brain controls ALL activities
• Emotion and cognition are intertwined
• Neurons can re-route circuits
• Brain and environment involved in delicate duet
• Brain never stops adapting and changing

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(No Transcript)
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Illustration by Lydia Kibuik, 2003
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EVOLUTION OF THE NEW BRAIN
Every mammals brain has the same basic
structure- cortex, cerebellum, and brain
stem cortical surface area is key
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CHALLENGE OF UNDERSTANDING THE BRAIN

• What is the link between the anatomy of a brain
  and the workings of the mindour thoughts,
  emotions, memories, and behaviors?
• There are no moving partsit does not operate
  mechanically as our hearts, legs, hands, and
  lungs do. So what is going on in there?

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BRAIN STRUCTURES

• Frontal Lobe
• Parietal Lobe
• Temporal Lobe
• Occipital Lobe

• Cerebellum
• Corpus Callosum
• Brain Stem

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INTEGRATION OF THE LOBES

• The different lobes of the brain work together
  like instruments in an orchestra to play music or
  letters in the alphabet to form words
• Each area makes specialized contributions to
  certain functions, but many brain regions
  participate in forming human thoughts and
  behaviors

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FRONTAL LOBE

• Seat of personality, judgment, reasoning, problem
  solving, and rational decision making
• Provides for logic, understanding of
  consequences, and emotional/behavioral regulation
• Governs impulsivity, aggression, ability to
  organize thoughts, and plan for the future
• Controls capacity for abstraction, attention,
  cognitive flexibility, and goal persistence
• Undergoes significant changes during adolescence
  not fully developed until mid 20s (Geidd, 2002)

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FRONTAL LOBE

• As the prefrontal cortex area of the frontal
  lobe matures, through experience and practice,
  teens can reason better, develop more impulse
  control, and make better judgments
• Prefrontal cortex is one of the last areas of the
  brain to fully develop (Sowell, 2001)
• Increased need for struc-
• ture, mentoring, guidance

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COMPONENTS OF EXECUTIVE FUNCTIONS AND SAMPLE
BEHAVIORS
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Brown et al., 2008
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TEMPORAL LOBES

• Responsible for hearing, understanding speech,
  and forming an integrated sense of self
• Responsible for sorting new information and for
  short term memory
• Contains the limbic-reward system (amygdala,
  hippocampus, nucleus acumbens, and vta)
• Developmental delays, deficits, or
  over-stimulation of the limbic area may increase
  vulnerability to high risk behaviors (Clark,
  Thatcher, Tapert, 2008)
• Matures around ages 18-22

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TEMPORAL LOBE/LIMBIC SYSTEM

• Limbic system regulates emotions and motivations
  particularly those related to survivalsuch as
  fear, anger, and pleasure (sex and eating)
• Feelings of pleasure/reward are very powerful and
  self-sustaining. Pleasurable behaviors activate
  a circuit of specialized nerve cells in the
  limbic area that is devoted to producing and
  regulating pleasure called the reward system

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REWARD SYSTEM

• Drugs of abuse activate the reward system in the
  limbic area of the brainproducing powerful
  feelings of pleasure
• Desire to repeat drug using behavior is strong
• Drugs of abuse can/do exert powerful control over
  behavior because they act directly on the more
  primitive, survival limbic structures over-ride
  the frontal cortex in controlling our behavior

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PARIETAL LOBES

• Integrate auditory, visual, and tactile signals
• Right lobe coordinates visual/spatial
  relationships
• Left lobe coordinates spoken or written language
• Matures around ages 16-17

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OCCIPITAL LOBES

• Primarily responsible for coordinating sight
• Primary visual area where pictures are received
  from the eyes and relayed to other parts of the
  brain for interpretation
• Visualization requires more than seeing the
  primary visual cortex processes information,
  temporal lobe recognize what we see, and the
  parietal lobes process information as we move
  through the space we see.

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• INFO FROM DANA BOOK

Robert Finkbeiner, Dana Brain Book
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CEREBELLUM

• Located at the base of the brain
• Responsible for motor coordination
• Recent research suggests that it is involved in
  coordinating thinking processes mental
  clumsiness (Geidd, 2002)
• Physical exercise is important for the
  development of the cerebellum undergoes
  significant change during adolescence

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CORPUS CALLOSUM

• Thick bundle of nerves that connects the two
  sides of the brain and relays information between
  the two cerebral hemispheres
• Involved in creativity and problem solving
• Influences language, learning, and associative
  thinking
• Changes significantly during adolescence (Geidd,
  1999)

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BRAIN STEM

• All nerve fibers pass through this area
• Performs sensory, motor, and reflex functions
• Contains vital nerve centers that control
  breathing, heart rate, body temperature, and
  gastrointestinal activity
• Connects the brain with the body

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BRAIN CIRCUITRY
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Brain Circuitry

• NEURON specialized cell designed to transmit
  information to other nerve cells and muscles
• Each neuron consists of a cell body, axon, and
  dendrite
• Axon an electricity conducting fiber that
  carries information away from the cell body
• Dendrite receives messages from other neurons
• Synapse contact point where one neuron
  chemically communicates with another neuron

Brain Facts, The Society for Neuroscience, 2002
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(Illustration by Lydia Kibiuk, 1996)
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BRAIN CIRCUITRY

• Neurons communicate by transmitting electrical
  impulses along their axons
• Axons send chemical neurotransmitter messages
  across a synapse to the receiving dendrite of the
  target neuron
• Each neuron has an average of 6,000 dendrite
  receptors
• Dendrite receptor sites are specialized areas
  lock and key or molecular handshake

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BRAIN CIRCUITRY

• A neuron may receive many different messages at
  the same time (Prioritize)
• Each neuron has to interpret incoming messages
• Neuronal communication is currently under intense
  study because it plays such a critical role in
  health and well being

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BRAIN CIRCUITRY

• Electrical impulses travel along axon at speeds
  up to 250 mph (mylenation)
• Neurons forging connections with other neurons
  underpin learning
• Our brains are adaptable and can reflect on and
  learn from experience
• Neural connections are shaped by genetics and
  experience

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BRAIN CIRCUITRY

• Gray matter contains neurons that are responsible
  for thinking (100 billion)
• White matter contains suportive cells with
  nutritive roles (dendrites1 trillion)
• Myelin is a layer of insulation that
  progressively insulates these supportive cells
  and is whitish in color
• Myelin makes white matter more efficientjust
  like insulation on electric wirescontributes to
  overall cognitive functioning (100x faster)
• Myelin affects the speed and quality of brain
  activity (Paus, et al., 1999)

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NEUROTRANSMITTERS

• All messages are passed to connected neurons
  through a form of chemicals called
  neurotransmitters
• Neurotransmitters are released from the end of
  the axon, cross the synapse, and bind to the
  specific receptors on the dendrites of the
  targeted neuron
• Neurotransmitters bind with specific receptor
  sites on the receiving dendrite

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MAJOR NEUROTRANSMITTERS

• Acetylcholine regulates memory
• Dopamine produces pleasure through the reward
  system multiple functions including controlling
  movement, regulates hormonal responses, important
  to cognition and emotion abnormalities in
  dopamine levels have been implicated in
  schizophrenia
• Serotonin plays a role in sleep involved in
  sensory perception and involved in controlling
  emotional states such as anxiety and depression

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MAJOR NEUROTRANSMITTERS

• Glutamate excites the firing of neurons, aids
  process of memory
• Gamma-aminobutyric (GABA) inhibits the firing
  of neurons

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DEVELOPMENTAL VULNERABILITY

• During adolescence, the prefrontal cortex (PFC),
  limbic system areas, and the white matter myelin
  are undergoing many changes (Chambers, 2003
  Spear, 2000)
• These areas serving cognitive, behavioral, and
  emotional regulation may be particularly
  vulnerable to adverse alcohol effects
• Deficits or developmental delays in these
  structures and their functions may underlie
  vulnerabilities to alcohol use/abuse (Clark,
  Thatcher, Tappert, 2008)

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OVERPRODUCTION AND PRUNING

• CRITICAL PEAKS OF BRAIN DEVELOPMENT

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OVERPRODUCTION AND PRUNING

• Brain development occurs in 2 basic stages
  growth spurts/overproduction of neurons and
  pruning
• Critical phases in utero
• 0-3 years
  overproduction
• 10-13 years
• Overproduction results in significant increase in
  the number of neurons and synapses
• Exuberant growth during these 3 phases gives the
  brain enormous potential

Begley, 2000 Geidd, 1999
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PRUNING

• These 3 critical phases are quickly followed by a
  process in which the brain prunes and organizes
  its neural pathways
• LEARNING is a process of creating and
  strengthening frequently used synapses (brain
  discards unused synapses)
• Brain keeps only the most efficient and strong
  synapses
• Children/teens need to understand that they
  decide which synapses flourish and which are
  pruned away (Geidd, 1999)

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PRUNING

• USE IT OR LOSE IT Reading, sports, music,
  video games, x-box, hanging outwhatever a
  child/teen is doingthese are the neural synapses
  that will be retained
• How children/teens spend their time is CRUCIAL to
  brain development since their activities guide
  the structure of the brain (Geidd, 1999)

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What sorts of media are young people consuming?
Every year young people will see about 1,000
commercials advertising beer. 2/3 of young people
have a TV in their room, 61 have no parental
guidelines. Annually alcohol manufactures spend
over 1 BILLION in TV, radio, print, and internet
advertising.
Young people sped an average of 1-2 hours daily
listening to music. 63 of rap songs make
reference to drug use, as do 10 of songs in
other genres.
Young people spend an average of 10 hours per
week on the internet. 58 of young people have
accessed websites of a violent or sexual
nature. 82 of websites target youth.
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BRAIN DEVELOPMENT

• Continued synaptic pruning, neural
  connection/integration, capacity to process
  information, and mylenation (driven by experience
  and practice) these structural changes are
  believed to underlie the functional integration
  of frontal regions with the rest of the brain
  adolescent into adult (Luna Sweeny, 2004)

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BRAIN DEVELOPMENT

• White matter development may underlie advancing
  executive functioning (Luna and Sweeney, 2004
  Luna et al., 2001)
• Delays or deficits in the development of PFC may
  result in neurodevelopmental dysmaturation
  which can lead to psychological dysregulation
• Psychological dysregulation is a deficiency in
  the ability to regulate attention, emotions, and
  behavior in response to environmental challenges
  (Clark and Winters, 2002)

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PSYCHOLOGICAL DYSREGULATION

• Alcohol Use Disorders (AUD) typically do not
  happen in isolation instead they appear to be
  correlated with persistent behavioral
  characteristics including
• attentional deficits ADD, ADHD
• conduct disorders anti-social
• irritability aggression, diminished
  constraint
• major depressive disorder depression, anxiety

Clark et al., 2005 Tappert et al., 2002 Chassin
et al., 1999 Tarter et al., 1999
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DEFINING ADOLESCENCE
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ADOLESCENCE HAS ALWAYS BEEN CHALLENGING

• Youth are heated by nature as drunken men by
  wine Aristotle (350 B.C.)
• I would that there were no age between 10-23,
  for theres nothing in between but getting
  wenches with child, wronging the ancientry,
  stealing, fighting Shakespeare The Winters
  Tale, Act III (..1594)

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DISPARITIES OF ADOLESCENCE

• Adolescence is a time of triumph, high energy,
  great potential, resilient health, new found
  skills, creativity, humor..
• Adolescence is also a time of turmoil often
  associated with high risk behaviors, impulsivity,
  and poor decision making
• Dramatic increase in death, disability, suicide,
  homicide, serious accidents, aggression,
  violence, emotional disorders, substance use, and
  risky sexual behaviors

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REWARD SENSITIVITY

• Changes in reward sensitivity that occur at
  puberty lead adolescents to seek more novelty and
  require a higher level of stimulation to achieve
  the same subjective feeling of pleasure
• Changes in the limbic system, neuro-
  endocrinology, and an immature self regulatory
  system are implicated (Steinberg, 2004)

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ADOLESCENCE

• Awkward period between sexual maturation and the
  attainment of adult roles and responsibilities
• Begins with the domain of physical/biological
  changes related to puberty, but it ends in the
  domain of social roles
• Encompasses the transition from the status of a
  child (one who requires monitoring) to that of an
  adult (responsible for behavior) Dahl, 2003

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STUDY OF ADOLESCENTS

• G. S. Hall, psychologist, began the modern study
  of adolescence about 100 years ago
• Increase in adolescent-related research in the
  early 1990s second increase began focusing on
  adolescent brain development in 1998
• Most research is conducted on babies and toddlers

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ADOLESCENCE

• Adolescence is much broader and longer than the
  teenage years alone (has changed significantly
  over the past 150 years)
• Adolescence now stretches across more than a
  decade, with pubertal onset often beginning by
  age 9-12 and adult roles delayed until mid
  twenties (Worthman, 1995)

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ADOLESCENCE

• In the early 1900s, the interval between puberty
  and achieving adult status was typically 2 years
  for girls and 4 years for boys (Schlegel and
  Barry, 1991)
• While puberty is occurring earlier in many
  industrial societies, marriage and other adult
  roles are often delayed in the U.S. the average
  age of menarche is 12 and average age of 1st
  marriage is 26 (Dahl, 2004)

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ADOLESCENCE

• Most elements of cognitive development show a
  trajectory that follows age and experience rather
  than the timing of puberty (Dahl, 2004)
• Research conducted by Martin, 2003, demonstrates
  a significant positive correlation between
  pubertal maturation and sensation seeking

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ADOLESCENCE

• PUBERTY
• Romantic motivation
• Sexual interest
• Emotional intensity
• Sleep cycle changes
• Appetite
• Risk for affective disorders (girls)
• Increase in risk taking, sensation seeking, and
  novelty seeking

• AGE/EXPERIENCE
• Planning
• Logic, reasoning
• Inhibitory control
• Problem solving
• Understanding consequences
• Affect regulation
• Goal setting and pursuit
• Judgment and abstract thinking

Dahl, 2004
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ADOLESCENCE VS. ADULTS

• Being a responsible adult requires developing
  self-control over behavior and emotions must be
  able to appropriately inhibit behaviors despite
  STRONG FEELINGS
• The ability to integrate these multiple
  components of behavior, cognition, and affect in
  the service of long term goals involves
  neurobehavioral systems that are among the last
  regions of the brain to fully mature (Dahl, 2004)

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NAVIGATING ADOLESCENCE

• The most widely implicated factor associated with
  maladaption vs. resilience in adolescence is
  REGULATORY CAPACITY (RC) Kupfer Woodward,
  2004
• Behavioral control (RC) requires tremendous
  effort adolescents need practice being
  consistent and integrating RC
• PFC and white matter development are needed for
  regulatory capacity

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NAVIGATING ADOLESCENCE

• What makes this possible?
• Driven by experience and practice
• Psychological regulation of attention, emotions,
  and behavior
• Continued synaptic pruning and mylenation
• Mentoring appropriate response patterns in the
  face of everyday life and decision making

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Critical Differences Between Adult and Adolescent
Thinking
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Why is it that a young person is not able to
drive a car until 16, vote until 18, drink
alcohol until 21, rent a car from a commercial
agency until 25, but in some states, can stand
trial for murder at age 12 or 13? (Dahl, 2004)
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DISPARITIES OF ADOLESCENCE

• Adolescence is a TRANSITIONAL period during which
  a child is becoming, but is not yet, an adult
• Adolescent brains are far less developed than we
  previously believed
• Normal adolescent development includes conflict,
  risk taking, facing insecurities, creating an
  identity, mood swings, self-absorption, etc.

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ADOLESCENT BRAIN DEVELOPMENT

• Underdevelopment of the frontal lobe/prefrontal
  cortex and the limbic system make adolescents
  more prone to behave emotionally or with gut
  reactions (Yurgelun-Todd, 1999)
• Adolescents tend to use an alternative part of
  the brain the AMYGDALA (emotions aggression)
  rather than the prefrontal cortex (reasoning) to
  process information

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Illustration by Lydia Kibiuk, 2003
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ADOLESCENT BRAIN DEVELOPMENT

• Amygdala and nucleus acumbens (limbic system
  within the temporal lobes) tend to dominate the
  prefrontal cortex functions this results in a
  decrease in reasoned thinking and an increase in
  impulsiveness
• Because of immature brains, adolescents do not
  handle social pressure, instinctual urges, and
  other stresses the way adults do
• A major part of adolescence is learning how to
  assess risk and consequences adolescents are
  not yet skilled at these tasks (Dahl, 2004)

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HOT AND COLD COGNITION

• Thoughts and emotions are intertwined teens
  need to develop a balance between cognitive and
  affective systems of the brain
• COLD cognition refers to thinking under
  conditions of low emotions and/or arousal
• HOT cognition refers to thinking under
  conditions of strong feelings or arousal
• Decisions made under conditions of strong affect
  are difficult to influence by cool rational
  thought alone

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HOT AND COLD COGNITION

• Decision making in teens cannot be fully
  understood without considering the role of
  emotions and the interaction between thinking and
  feeling (Dahl, 2003)
• Teen decisions are unlikely to emerge from a
  logical evaluation of the risk/benefits of a
  situation rather decisions are the result of a
  complex set of competing feelings desire to
  look cool, fear of being rejected, anxiety about
  being caught, excitement of risk, etc.

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HOT AND COLD COGNITION

• Adolescent brain is a vulnerable system that
  could fail under hot high demanding situations
  where the circuitry is not sufficiently
  established to sustain adult level cognitive
  control of behavior in the face of heightened
  states of emotion, motivation, distracting
  stimuli, or competing tasks (Luna Sweeny, 2003)

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ADOLESCENT BRAIN

• DLPFC is linked to the ability to inhibit
  impulses, weigh consequences, prioritize, and
  strategize this area is still under
  construction until late 20s (Giedd, 1999)
• Wernickes area (reception of speech) and Brocas
  area (production of speech) undergo substantial
  changes during the teen years impacts ability
  to listen and express oneself

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ADOLESCENT BRAIN DEVELOPMENT

• Adolescents are not very skilled at
  distinguishing the subtlety of facial expression
  (excitement, anger, fear, sadness, etc.)results
  in a lot of miscuesleads to lack of
  communication and inappropriate behavior
• Differences in processing, organization, and
  responding to information/events leads to
  misperceptions and misunderstanding verbal and
  non-verbal cues

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Adult Brain
Adolescent Brain
YURGELUN-TODD, 1999
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ADOLESCENT BRAIN DEVELOPMENT

• To appreciate consequences of risky behavior, one
  has to have the ability to think through
  potential outcomes and understand the permanence
  of consequences, due to an immature prefrontal
  cortex, teens are not skilled at doing this
• Teens do not take information, organize it, and
  understand it in the same way that adults dothey
  have to learn how to do this

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ADOLESCENT BRAIN DEVELOPMENT

• Important to understand that teens often fail to
  heed common sense or adult warnings because they
  simply may not be able to understand and/or
  accept reasons that seem logical and reasonable
  to adults (difference in evaluating positive
  negative consequences Fromme et al., 1997)
• Adolescents may know right from wrong, but they
  may not be able to prioritize when stressed with
  social/peer pressure
• NEVER assume that you and a teen are having the
  same understanding of a conversation