Drugs & Consciousness
Drugs & the Brain
• Blood brain barrier – layer
of capillaries that protect the
brain
• Psychoactive drugs – small
enough to pass through
blood-brain barrier
 Change our perceptions &
moods by acting on neurons
& neurotransmitters in the
brain
Remember that drugs are
either….
• Agonists
• Enhance NT’s effect by causing it to be released,
mimicking it, or by flooding the synapse & overstimulating receiving cell
• Antagonists
• Block NT from being released, block it from being
received
If a drug is used often, a tolerance is created
for the drug.
- Thus you need more of the drug to feel the same
effect.
If you stop using a drug you can develop
withdrawal symptoms.
Addiction – Compulsive Cravings
Despite Adverse Effects
• Physical
dependence
– User feels physical
pain & intense
cravings when not
taking drug
• Psychological
dependence
– Used to relieve
stress or negative
emotions
Depressants
• Slow down body
processes by
calming neural
activity
Depressants
include:
• Alcohol
• Anxiolytics
(barbiturates and
tranquilizers)
• Opiates
Stimulants
• Speed up body
processes by
exciting neural
activity
• More powerful ones
(like cocaine) give
people feelings of
invincibility.
• Caffeine, nicotine
Hallucinogens
• Psychedelics
• Causes changes in
perceptions of
reality
• Evoke sensory
images in absence
of sensory input
• Reverse tolerance or
synergistic effect
(less is needed to
produce same effect
if used often)
Barbiturates (Tranquilizers)
•
•
•
•
•
Depress NS activity
Agonist for GABA
Induces sleep, reduces anxiety
Impairs memory & judgment
Possible death
Caffeine/Nicotine
• Caffeine – most widely consumed drug
– Agonist for epinephrine
– Agonist for dopamine
(in prefrontal cortex)
– Tolerance if used often
– Effects include anxiety,
restlessness, insomnia
• Nicotine
– Agonist for ACh (acetylcholine) and dopamine
– Reduces circulation, increases heart rate & blood
pressure, suppresses appetite, reduces stress
Mouse Party
• Go to
http://learn.genetics.utah.edu/content/addictio
n/drugs/mouse.html to fill out the rest of the
types of drugs (besides
barbiturates/tranquilizers, caffeine/nicotine,
which were described above)
Other Negative Effects of
Marijuana Use
• Harder on lungs than cigarette smoke (Wu et al.)
• Brain cell loss accelerates with large doses (Landfield et
al.)
• Memory impaired long after marijuana’s effect ahs
worn off (Pope & Yurgelun-Todd; Smith)
• Marijuana suppresses immune system (Childers &
Breivogel)
• Lowers testosterone and sperm count in men
(http://www.pbs.org/thebotanyofdesire/altering-consciousness.php)
BIOPSYCHOSOCIAL
APPROACH
• Biological
Influences
– Genetic
predispositions
• Identical twins =
increased risk if one
has addiction
• Adopted more
susceptible if
biological parent
used drugs
• Psychological Inf.
– Depression
– Stress or feelings of failure
– Reinforcement or
observational learning
• Social/Cultural Inf.
– Society’s expectations &
acceptance/lack of
– Peers influence drug use
(more likely to use if friends
do)
Prevention
• Education is related to
drug use. Roughly 15%
of U.S. college dropouts
smoke, and 42% of high
school dropouts smoke
(Ladd, 1998)
• Hope matters. Those
who believe their lives
are meaningless are
more likely to use drugs
(Newcomb & Harlow,
1986).
• Genetics plays a role.
Gene has been found to
occur more often
among alcoholdependent people
(Noble, 1993)
• Peers count. If the
friends you hang out
with DON’T use drugs,
there is a good chance
you won’t either!