Psychological Disorders
14.1 Substance Abuse
Drug Mechanisms
Antagonist → a drug that blocks a neurotransmitter
Agonist → a drug that mimics or increases the effects of a neurotransmitter
➔ a mixed agonist-antagonist is an agonist for effects and an antagonist for others
➔ affinity → a drug’s property to bind to a receptor
➔ efficacy → a drug’s tendency to activate a receptor
Predispositions
a. Genetic Influences
➔ after anyone drinks alcohol, enzymes in the liver metabolize it to acetaldehyde (a
toxic substance), which us then converted to acetic acid (chemical used for energy)
by the enzyme acetaldehyde dehydrogenase
● alcohol → acetaldehyde → (through acetaldehyde dehydrogenase) → acetic acid
➔ gene that produces less acetaldehyde dehydrogenase ⇒ alcohol causes nausea,
flushing of the face, headaches, etc.
b. Environmental Influences
➔ prenatal exposure to alcohol increases alcohol consumption after birth
➔ childhood environment is also critical
c. Behavioral Predictors of Abuse
➔ sons of alcoholics show less than average intoxication after drinking a moderate
amount of alcohol ⇒ more likely to increase consumption
Synaptic Mechanisms
a. The Role of Dopamine
➔ when rats have the opportunity to self-stimulate the brain
(with dopamine), they engage in this activity all day, don’t eat
and sleep a minimal amount
➔ the release of dopamine in the nucleus accubens is related
with feelings of reward; this region is important for reinforcing experiences
➔ a lot of addictions work on dopamine release (e.g. gambling, sex, video games)
➔ however, the role of dopamine has been overemphasized: a lot of drugs do not
increase dopamine by a lot, and drugs via dopamine failed to alleviate addictions
b. Cravings
➔ people with addictions have trouble breaking any habit, not just a drug habit
14.1 Substance Abuse
Drug Mechanisms
Antagonist → a drug that blocks a neurotransmitter
Agonist → a drug that mimics or increases the effects of a neurotransmitter
➔ a mixed agonist-antagonist is an agonist for effects and an antagonist for others
➔ affinity → a drug’s property to bind to a receptor
➔ efficacy → a drug’s tendency to activate a receptor
Predispositions
a. Genetic Influences
➔ after anyone drinks alcohol, enzymes in the liver metabolize it to acetaldehyde (a
toxic substance), which us then converted to acetic acid (chemical used for energy)
by the enzyme acetaldehyde dehydrogenase
● alcohol → acetaldehyde → (through acetaldehyde dehydrogenase) → acetic acid
➔ gene that produces less acetaldehyde dehydrogenase ⇒ alcohol causes nausea,
flushing of the face, headaches, etc.
b. Environmental Influences
➔ prenatal exposure to alcohol increases alcohol consumption after birth
➔ childhood environment is also critical
c. Behavioral Predictors of Abuse
➔ sons of alcoholics show less than average intoxication after drinking a moderate
amount of alcohol ⇒ more likely to increase consumption
Synaptic Mechanisms
a. The Role of Dopamine
➔ when rats have the opportunity to self-stimulate the brain
(with dopamine), they engage in this activity all day, don’t eat
and sleep a minimal amount
➔ the release of dopamine in the nucleus accubens is related
with feelings of reward; this region is important for reinforcing experiences
➔ a lot of addictions work on dopamine release (e.g. gambling, sex, video games)
➔ however, the role of dopamine has been overemphasized: a lot of drugs do not
increase dopamine by a lot, and drugs via dopamine failed to alleviate addictions
b. Cravings
➔ people with addictions have trouble breaking any habit, not just a drug habit
