Title: ADOLESCENT BRAIN DEVELOPMENT
1ADOLESCENT BRAIN DEVELOPMENT
- TIME OF TURMOIL AND TRIUMPH
- BARBARA SULLIVAN, Ph.D.
- September 14 and 15, 2009
2GOALS
- 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
3CAVEATS
- 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
4- BRAIN STRUCTURES AND FUNCTIONS
5BRAIN 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
6(No Transcript)
7Illustration by Lydia Kibuik, 2003
8EVOLUTION OF THE NEW BRAIN
Every mammals brain has the same basic
structure- cortex, cerebellum, and brain
stem cortical surface area is key
9CHALLENGE 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?
10BRAIN STRUCTURES
- Frontal Lobe
- Parietal Lobe
- Temporal Lobe
- Occipital Lobe
- Cerebellum
- Corpus Callosum
- Brain Stem
11INTEGRATION 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
12FRONTAL 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)
13FRONTAL 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
14COMPONENTS OF EXECUTIVE FUNCTIONS AND SAMPLE
BEHAVIORS
15Brown et al., 2008
16TEMPORAL 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
17TEMPORAL 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
18REWARD 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
19PARIETAL 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
20OCCIPITAL 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.
21Robert Finkbeiner, Dana Brain Book
22CEREBELLUM
- 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
23CORPUS 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)
24BRAIN 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
25BRAIN CIRCUITRY
26Brain 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
27(Illustration by Lydia Kibiuk, 1996)
28BRAIN 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
29BRAIN 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
30BRAIN 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
31BRAIN 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)
32NEUROTRANSMITTERS
- 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
33MAJOR 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
34MAJOR NEUROTRANSMITTERS
- Glutamate excites the firing of neurons, aids
process of memory - Gamma-aminobutyric (GABA) inhibits the firing
of neurons
35DEVELOPMENTAL 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)
36OVERPRODUCTION AND PRUNING
- CRITICAL PEAKS OF BRAIN DEVELOPMENT
37OVERPRODUCTION 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
38PRUNING
- 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)
39PRUNING
- 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)
40What 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.
41BRAIN 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)
42BRAIN 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)
43PSYCHOLOGICAL 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
44DEFINING ADOLESCENCE
45ADOLESCENCE 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)
46DISPARITIES 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
47REWARD 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)
48ADOLESCENCE
- 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
49STUDY 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
50ADOLESCENCE
- 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)
51ADOLESCENCE
- 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)
52ADOLESCENCE
- 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
53ADOLESCENCE
- 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
54ADOLESCENCE 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)
55NAVIGATING 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
56NAVIGATING 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
57Critical Differences Between Adult and Adolescent
Thinking
58Why 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)
59DISPARITIES 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.
60ADOLESCENT 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
61Illustration by Lydia Kibiuk, 2003
62ADOLESCENT 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)
63HOT 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
64HOT 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.
65HOT 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)
66ADOLESCENT 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
67ADOLESCENT 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
68Adult Brain
Adolescent Brain
YURGELUN-TODD, 1999
69ADOLESCENT 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
70ADOLESCENT 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