Inside the Teen’s
Brain:
What Makes Teens Tick?
Ann Tilton, MD
Based on
Primal Teen
Barbara Strauch
Crazy by Design
• Why do they do what they do?
– Hormones
– Friends
–My fault……
– Brain
What is going on?
• Prior thoughts:
– Brain was finished/cooked
– 1st 3 years are the most important
• NOT SO
• Now:
– Dramatic transformation
– Stumbling block
• Relatively few die
• In animals “over in a blink”
Study
• NIH- Jay Giedd
– 500 kids MRI for normals
– Found the gray matter was thickening
and then thinning (Nature and Neuroscience)
– Areas
• Parietal lobes
• Temporal lobes
• Frontal lobes
What is Normal?
• Frontal lobes synapses– by age 2 exceed adult levels 2X and
adult level by 16-17- Huttenlocker
– Confirmed by Chigani based on PET
– More is not necessarily better (fragile X)
• Prefrontal cortex develops until
adulthood
• MORE vunerable if exposed
Altered States
• Enrichment
– Rats in a more complex environment
have thicker cortex – increased dendrites
• Deprivation
– Romanian Orphans
• Chigani - Less active in limbic area (facial
recognition and attachment)
Age of Impulse
• Beat the Truck
• Internet
• Irresistible urge……
Age of Impulse
• Pre frontal cortex
– Limbic- gut and emotion
– Separates humans
• 29% growth
• Chimps 17%, cats 7%
– The great Inhibitor- teens are capable but
do not have the breaks
– Parents need to be the teen’s “frontal
cortex”
• In some cultures the child is an adult at 12
– ( in a very ordered society)
Making Connections
• Myelin jumps 100% in teen years
– Good and bad
• Growth especially in the cingulate
gyrus and hippocampus
– Gut reaction
• Calm down– Decreased Glutamate
Making Connections
• World is seen differently
– fMRI – Yurgeleu-Todd
• Teen sees a picture of fear in a face
– SEES ANGER
– Social cues
• Do not get it right
Adolescent Animal
• Rhesus monkey
– Monkeys are better if raised by nurturing
mothers and terry cloth mothers
– Peer-raised have loose attachments
– The males mature later – protective
• Shy and offensive
• Middle school
Wake UP!!
• Melatonin surges 2 hours later
• Adults respond by:
having them go to bed early and start
school earlier
• Sleep loss leads to:
– Anger
– Silly
– Increased emotion
Risky BusinessWhy do they do what they
do?
• Most do a few stupid things
– Normal & necessary
– Risky
• 20% of 7th and 60% of 11th graders have had
sexual intercourse
• 10% drank weekly
• Probably not “immortal” - just their
own logic
Risky BusinessWhy do they do what they
do?
• Neuroscience of risk
– Use prefrontal cortex
• Thrills:
– Dopamine• Smooth movement and Pleasure – Reward
circuit
• Increased in
– Videogames
– Addiction / drugs
THRILLS!!!
• Novelty seekers
– 50% heritable – Kennedy legacy
– High – sensitive to reward
– Low- safe except with alcohol
• Dopamine decreases from childhood
(except pre frontal cortex)
– Teens are depleted
THRILLS!!!
• Addiction
– Drugs - cocaine, heroin, nicotine,
alcohol all increase dopamine
• Overload down regulates dopamine
Drugs
• Alcohol
– Alcohol in Adolescents is less sedating
– 50% alcoholics traced to a gene related to
the reward system – dopamine, serotonin,
and endorphins
Drugs
• Alcohol
– Rats
• Damage to the hippocampus 10% smaller
– With 2 drinks per day
– More Problems with stopping drinking
• With alcohol the NMDA-glutamate receptors are
blocked – then more sensitive
– Too much calcium is let in - cell suicide
– Death in the hippocampus
Drugs
• Alcohol
– Worse for teenagers
• 2 drinks a day leads to 10% memory loss
• Heavy drinkers (5 drinks in a row at least 1X
in 2 weeks)
– 30% 12th graders
– 26% 10th graders
– 14% 8th graders
Drugs
• Alcohol
– Worse for teenagers who drink before
15yr
• 5X more likely to be a heavy drinker
• 10X more likely to be involved in a fight
• 7X more likely to be in a car wreck
Smoking
• Smoking and Panic
– If smoke 15X risk of Panic attacks
• Nicotine mimics ACH
– Esp in the ventral tegmental area where
there are many neurons that produce
dopamine
• Produce 2X the number of receptors = leads
to craving
Smoking
• Females
– are more susceptible due to estrogen
– Hippocampus damage
• All
– Lower serotonin levels which lead to
depression
– Prone to infections
Schizophrenia
• Theories:
– Abnormality of Dopamine and GABA
– Normally loose 15% of excess cortical
gray matter
• Problem with pruning- Schizophrenics loose
25%
– Prefrontal cortex abnormalities
Conclusions
• Science continues to show
behavior and brain structure
dance in tandem
Thought…..
The Chinese symbol for
Change is
both Peril and Possibilities