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Case Study#2: Effect of Alcohol/Drugs on Teen Brain. Yehuda Ben-Shahar, PhD Department of Biology, Washington University in St. Louis. Drosophila melanogaster. Courtship as a model for social behaviors. Drug use in teenagers – what does it do to their brains?. - PowerPoint PPT Presentation
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Case Study#2: Effect of
Alcohol/Drugs on Teen Brain Yehuda Ben-Shahar, PhDDepartment of Biology, Washington University in St. Louis
Drosophila melanogaster
Courtship as a model for social behaviors
Drug use in teenagers –
what does it do to their
brains?
Short-term versus long-term effects of use of, and addiction to drugs
Huntington’s disease = 100%
Sickle Cell Anemia = 100%
Obesity = 60%-90%
Breast Cancer = 30%
Asthma = 25%
Type II Diabetes = 26%
Alcohol dependence = 38%-64%
Nicotine dependence = 75%
Heritability
But… the environment is a key factor as well!
Why should we care?
Data from the NIDA InfoFacts: High School and Youth Trends
Drugs – mode of action
Most known drugs affect neurotransmission in the brain – typically by acting on specific receptors
Alcohol, Barbiturates, and Benzodiazepines
These drugs exert their effects mostly via the gamma-Aminobutyric acid (GABA) signaling pathway
GABA is the principle inhibitory neurotransmitter in the mammalian brain
Alcohol, Barbiturates, and Benzodiazepines
Short-term effects Potentiates GABA-activated
Cl- channels Allows more Cl- to cross the
membrane Increases inhibition in the
post-synaptic cell Increases turnover of
norepinephrine and dopamine,
Decreases transmission in acetylcholine systems
Increases production of beta-endorphin in the hypothalamus.
Alcohol, Barbiturates, and Benzodiazepines
Long-term effects Damage to the frontal lobes
of the brain An overall reduction in brain
size Increase in the size of the
ventricles Alcoholism can cause
Vitamin B-1 (thiamine) deficiency, leading to Wernicke-Korsakoff syndrome, characterized by amnesia, apathy and disorientation.
Embryonic rat brain
Use of alcohol despite severe social or physical consequences.
Characterized by (some or all of the following):
Tolerance
Withdrawal
Uncontrollable use
Social, occupational, recreational consequences
Use continued despite knowledge of alcohol-related harm
Alcohol Dependence
First behavioral disorder to have a validated genetic finding
Subjects of Asian descent noted to have facial flushing and decreased tolerance compared to subjects of European descent
1980 – Found 50% of Japanese post-mortem liver extracts were missing aldehyde dehydrogenase (ALDH) isozyme I
Genetics of Alcohol Dependence
Elevated ethanal (acetaldehyde) levels cause Facial flushing Nausea Tachycardia
Causes behavioral aversion to alcohol
1/3 susceptibility to alcoholism as compared to wild-type
Mechanism of disulfiram (Antabuse)
ALDH isozyme I deficiency
Marijuana
Marijuana
Short-term effects Delta-9 tetrahydrocannabinol or
"THC” binds to cannabinoid receptors, which exist in many areas of the brain
Affects the levels of norepinephrine, dopamine, serotonin, and GABA in the brain
Relaxation
Reduced coordination
Reduced blood pressure
Sleepiness
Disruption in attention
An altered sense of time and space
Marijuana
Long-term effects Whether marijuana usage leads to addiction or long-
term mental abnormalities is still controversial and a topic of current research
Data suggest that onset of schizophrenia in susceptible individuals is associated with cannabis use
Because marijuana contains many other chemicals that are also inhaled, it leads similar respiratory problems as smoking cigarettes, as well as cancer and immune deficiencies