Psychological disorders Flashcards
Drug mechanism
Antagonist
agonist :
Most commonly abused drugs are derived from plants
(e.g., nicotine in tobacco)
• Antagonist
– Drug that blocks a neurotransmitter
• Agonist
– Drug that mimics or increases an effect
Drug’s affinity for a receptor
Efficacy
• Drug’s affinity for a receptor
– Measure of drug’s tendency to bind to it
– Ranges from strong to weak
lect : high affinity = binds well
low affinity - doesnt bind as well
Efficacy: tendency to activate the receptor • A drug’s effectiveness and side effects vary from one
person to another
– Abundance of each type of receptor varies between
individuals
Predispositions
People differ in their predisposition to alcohol or drug
abuse
• Certain aspects of brain function and behavior are
present from the start in people with a familial
disposition to addiction
– Not all individuals develop addiction
Genetic Influences
• Twin studies confirm strong influence of genetics on
vulnerability to alcohol/drugs
• Many addiction-linked genes have been identified, each
with a small effect
– Genes affect the probability of substance use, but effects
vary depending on environment
– People with a gene for producing less acetaldehyde
dehydrogenase metabolize acetaldehyde (from alcohol)
more slowly
§ Those individuals tend to drink less and have fewer
problems with alcohol abuse (e.g., China and Japan)
Environmental Influences
• Prenatal environment contributes to risk for alcoholism
• Childhood environment is critical
– Careful parenting supervision decreases likelihood of
developing impulsive behavior that leads to abuse
• Alcoholics that develop alcohol problems before age 25
tend to have family history and a genetic predisposition and rapid onset of problems
Behavioral Predictors of Abuse
research findings
• Research findings
– Sons of alcoholics show less than average intoxication
after drinking a moderate amount of alcohol § Low level of intoxication may influence person to keep
drinking § Probability of developing alcoholism is greater than 60
percent
– Alcohol decreases stress for most people, but more so
for sons of alcoholics
pic in slide 9
Synaptic Mechanisms
• Nearly all abused drugs affect several kinds of
receptors
• The effects while the drug is in the brain differ from
effects that occur during withdrawal, and effects
responsible for cravings
• Efforts to alleviate drug abuse must consider a variety
of mechanisms
The Role of Dopamine
James Olds and Peter Milner , what did they do ?
Nucleus accumbens , what is it ?
• James Olds and Peter Milner (1954)
– Stimulating rat brains: missed target and hit septum
causing rats to respond favorably
– Discovered that rats would push a lever to produce
electrical self-stimulation of the brain
• Nucleus accumbens
– Central to reinforcing experiences of all types
– Location where addictive drugs release dopamine or
norepinephrine
Other experiences that release dopamine in the
nucleus accumbens
– Sexual excitement – Music – Taste of sugar – Imagining something pleasant – Habitual gambling and video game playing
Dopamine release essential for all addictions and all
substance abuse?
– Not so fast: dopamine contributes to reinforcement, but
no longer appears to be as central as previously believed
Cravings
• Insistent search for the activity
– Distinctive feature of addictions
• Even after long period of abstinence, cues can trigger a
craving
• Studies in rats show repeated exposure to an addictive
substance alters receptors to become more responsive
to the addictive substance
– Less responsive to other types of reinforcement
Tolerance
– Decrease in effect as an addiction develops
– Drug tolerance is learned, to a large extent
§ Can be weakened through extinction procedures
Withdrawal
– Body’s reaction to absence of the drug
– One hypothesis is that addictive behavior is an attempt to avoid withdrawal symptoms
Modified hypothesis ?
for tolerance and withdrawal .
explain the study .
• Modified hypothesis: person with an addiction may use
the substance to cope with stress • Studies in rats have shown:
– Receiving an addictive drug during a withdrawal period is
a powerful experience § Associated relief can cause craving the drug under other
types of stressful experiences
Treatments
• Some addicts able to decrease use or quit on their own
• Alcoholics Anonymous (or similar group)
• Cognitive-behavioral therapy
– Contingency management includes rewards for
remaining drug-free
• Medication—not as common, but some options are
available
Medications to Combat Alcohol Abuse
• Antabuse (disulfiram)
– Results in sickness after drinking
– Taking a nausea-inducing drug after drinking, to
associate the two—learned aversion § Approach has not become popular
• Naloxone and naltrexone
– Block opiate receptors and decrease pleasure from
alcohol
• Drug effectiveness varies with user’s motivation to quit
Medications to Combat Opiate Abuse
• Methadone as a safer alternative – Similar to heroin and morphine § Activates same brain receptors and produces same effects – Can be taken orally, absorbs slowly, and leaves the brain slowly § “Rush” and withdrawal both reduced • Buprenorphine and LAAM – Similar to methadone
Mood Disorders
• Major depression symptoms
– Person feels sad and helpless most of the day every day
for long periods of time
– Person does not enjoy anything and cannot imagine
enjoying anything
– Fatigue, feelings of worthlessness, or contemplation of
suicide
– Trouble sleeping
– Cognitive problems: low motivation, impaired memory,
concentration problems, and impaired sense of smell
Major Depressive Disorder
• Absence of happiness is a more reliable symptom than
increased sadness
– More common in women during the reproductive era
– Affects five percent of adults with a given year
§ 10 percent lifetime prevalence
• Some people suffer long-term depression
– More common to have periodic episodes of depression
Genetics of depression
• Depression has a moderate degree of heritability
• No one gene has been identified as clearly linked to
depression
– People with early-onset depression (before age 30) more
likely to have relatives with depression as well as relatives with anxiety disorders, neuroticism, ADD, OCD, IBS, and migraine headaches
– Late onset depression (after age 45) linked to relatives
with circulatory problems
what is the hypothesis + evidence of genetics in regards to depression ?
• Hypothesis: the effect of a gene varies with the
environment • Evidence:
– Young adults with the short form of the serotonin
transporter gene who experienced stressful experiences had a major increase in probability of developing depression
– Long-form of gene less susceptible to stressful events;
one long and one short-moderate risk – Short-form may increase depressive reaction to stressful
events—especially childhood stress
Abnormalities of Hemispheric Dominance - Depression
• Brain activity associated with depression
– Decreased activity in the left prefrontal cortex
– Increased activity in the right prefrontal cortex
– Imbalance stable over the years, despite symptom
changes
• People with depression tend to gaze to the left when
asked to do a verbal task
– Most people gaze to the right
Antidepressant Drugs – Categories
• Many drugs used to treat psychiatric disorders
discovered by accident
• Categories of antidepressant drugs
– Tricyclics
– Selective serotonin reuptake inhibitors (SSRIs)
– Monoamine oxidase inhibitors (MAOIs)
– Atypical antidepressants
Tricyclics
• Tricyclics (such as imipramine; Tofranil)
– Block transporter proteins that reabsorb serotonin,
dopamine, and norepinephrine into the presynaptic neuron after release
– Also block histamine receptors, acetylcholine receptors,
and certain sodium channels
– Side-effects include drowsiness, dry mouth, difficulty
urinating, and heart irregularities
pic slide 29
SSRIs
• Selective serotonin reuptake inhibitors (SSRIs)
– Block the reuptake of the neurotransmitter serotonin
– Examples: fluoxetine (Prozac), sertraline (Zoloft),
fluvoxamine (Luvox), citalopram (Celexa), and paroxetine (Paxil)
– Work in a similar fashion to tricyclics but specific to the
neurotransmitter serotonin
SNRIs
• Serotonin norepinephrine reuptake inhibitors (SNRIs) – Examples: duloxetine (Cymbalta) and venlafaxine
(Effexor) – Block reuptake of serotonin and norepinephrine
• Unlike other antidepressants, the SNRIs improve
certain aspects of memory