The Teenage Brain
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The Teenage Brain

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The Teenage Brain The Teenage Brain Presentation Transcript

  • The Teenage Brain “ Youth are heated by nature as drunken men by wine.” Aristotle
  • New Thinking
    • Scientists once thought that all of the brain’s cells were present at birth and that all connections were established and “hard wired” in infancy and early childhood
      • The brain has reached 90 percent of its full size by the age of 6
    • New research shows the brain continues to evolve through the teens & early twenties
    • This may help explain why teens act the way they do.
  • The Chicken & The Egg: The Effect of Puberty
    • Adolescent brain development is influenced by pubertal maturation
    • Puberty is the onset of sexual maturation
    • Includes changes in three separate neuroendocrine axes:
      • Gonadal
      • Adrenal androgens
      • Growth
  • Neuroendocrine Changes
    • Gonadarche: turning on the hypothalamic-pituitary-gonadal axis
      • Leads to estrogen production & breast development in girls
      • Testosterone production & maturation of male genitalia in boys.
    • Adrenarche: turning on adrenal androgen production in both boys & girls
      • Contributes to development of secondary sex characteristics
    • Growth: growth hormone secretion
      • Rapid physical growth
      • Changes in body composition .
  • The Role of Puberty in Brain Development
    • Brain changes that contribute to the cascade of hormone changes
    • Pubertal brain changes that are caused by maturational hormonal increases
    • Maturational brain changes that occur relatively independent of puberty
    • Maturational processes linked to puberty in indirect ways
      • e.g., new experiences that occur as a result of sexual maturation
  • Teen Brains Are Different
    • Most of the new developments in the study of teenage brains comes from magnetic resonance imaging (MRI)
      • Studies by Dr. Jay Giedd - Child Psychiatry Branch of NIMH
    • Images show thickening in gray matter on the outer part of the brain peaks at age 11 in girls and at age 12 in boys.
    • During the teen years, the brain trims back excess cells and connections
  • Adolescent Risk Taking
    • Mortality rises during adolescence, then comes back down
      • 32% of deaths during this period result from motor vehicle accidents
      • mortality is 2 to 3 times greater in males than females.
    • Some aspects of teenage behavior (e.g. mood swings & risk taking) may be explained by brain development
  • Risk Taking: It’s All in Your Head
    • MRI shows one of the last parts of the brain to complete maturation is the prefrontal cortex
      • This is the part of the brain responsible for planning, judgment and self-control
    • Maturation of neural networks governing self-regulation doesn't occur until late in adolescence
    • Sensitivity to rewards is different in adolescents than in adults
      • Seek higher levels of stimulation to achieve the same feeling of pleasure
    • Increased risk-taking during adolescence is normal and biologically driven
  • Other Important Developments
    • White matter increases linearly during adolescence
    • The cerebellum also grows in volume.
    • Adolescence is the most efficient time for motor learning
  • Adolescence & Schizophrenic Brains
    • Studies of adolescent brain development may lead to greater understanding of schizophrenia & vice versa
      • David A. Lewis - University of Pittsburgh
    • Schizophrenics show impaired maturation of the circuitry of the prefrontal cortex.
      • working memory is impaired
    • Connections regulating the transmission of dopamine must be intact for working memory to function properly.
  • The Connection
    • A reduction in excitatory synapses occurs during adolescence
    • This reduction is even greater in schizophrenia.
    • The reduced number of excitatory synapses may explain the impairment of working memory in schizophrenia and the onset of its symptoms during adolescence.
  • MRI of Schizophrenic Brain
    • Brain scan of Schizophrenic patient (right) and normal brain (left). The normal brain shows more activity in the frontal cortex.
  • Stress and Brain Development
    • Changes in reproductive and stress hormones can influence behavior.
    • Hormonal changes during adolescence can also trigger depression.
    • Stress can cause hormone changes by increasing cortisol levels.
  • Brain Plasticity, Stress & Hormones
    • Experiences and behaviors encountered early in life can effect how the brain changes to adapt to its environment.
    • Repeated stress increases anxiety and aggression.
    • Stress can cause physical changes in the brain that result in changes in behavior as well.
    • Stress increases the size of the amygdala and causes shrinkage of the hippocampus.
    • Brain changes can also be observed in studies of patients with major depression.