Lecture 3: psychostimulants Flashcards
psychostimulants
what is a stimulant?
Increases alertness and energy, often elevating mood and the appeal of drug-paired events via increase of catecholamine transmission (DA, NE, E)
where do stimulants act on? what are their general effects?
block uptake or induce release of catecholamine transporters
what are the different types of stimulants, with a few examples?
- Plant based: cocaine, ephedra, Khat leaves
- synthetic: d-Amphetamine, meth-amphetamine, methylphenidate, MDMA, modafinil
do stimulants enhance cognition in healthy individuals?
unclear, mostly expectancy/placebo effect
effect of Methylphenidate on cognition in healthy people
small improvements in working memory, processing speed and subjective alertness, but increased perseverative and other errors
effect of Modafinil on cognition in healthy people
small improvements in working memory and subjective alertness, but induced overconfidence in sleep-deprived youth
effect of Caffeine on cognition in healthy people
small improvements in memory and learning
what is the severity of development of substance use disorders of stimulants?
moderate to severe with higher rates people with comorbidities (e.g. other SUDs and psychiatric disorders)
varies with substance:
nicotine (most addictive) > cocaine > alcohol > cannabis
how long does it take from dependence to remission?
depends on the substance:
nicotine (slowest) > alcohol > cannabis > cocaine (fastest)
what are “internalizing” co-morbidity?
Difficulty regulating inwardly directed emotional turmoil.
e.g. Sadness, fear, self-critical perfectionism
what are “externalizing” co-mobidities?
Difficulty regulating outwardly directed emotional turmoil.
e.g Impulsivity, irritable, aggression, etc.
what are some environmental factors that can lead to internalizing and externalizing?
physical abuse, emotional abuse, emotional neglect, physical neglect, sexual abuse
what disorders do “internalizing” and “externalization” lead to?
internalization: major depression, anxiety, panic disorder, animal phobia, situational phobia
externalization: alcohol dependence, other drug dependence, adult antisocial behavior, conduct disorder
what are HiTOPs (Hierarchical Taxonomy of Psychopathology)
“Biological parameters linked to higher levels influence a wider range of related behaviors than those linked to lower levels.
what are the main models to see “why they can’t stop”?
- Increased goal-directed approach (conditioned and sensitized incentive salience).
- Development of compulsions (an inability to disengage from outcome-insensitive habits).
- Switch from approach (to reward) to avoidance (of stress & withdrawal)
how does cue-induced reinstatement change with the amount of time of withdrawal (for cocaine and Heroin) ?
increases with time:
cocaine: increase up to 2 months after, where it plateaus
heroin: all time high at 2 weeks, where it gradually decreases after
effect of withdrawal in drug-seeking behavor
does not induce drug seeking, until you learn that taking the drug helps with withdrawal effects
what is the effect of giving a DA antagonist of cocaine self-administration?
- breakpoint is lower (decreases willingness to give effort for the drug)
- injection rate is higher
- Drug-induced reinstatement prevented by DA antagonists
(cue- and stress-induced reinstatement is decreased)
role of the ventral and the dorsal striatum in withdrawal
ventral: linked to reward-seeking behavior
dorsal: linked to habit-like behaviors (willing to go through withdrawal symptoms if it means that they will get a drug afterwards)
where in the brain do we see dopamine response with cocaine, amphetamine, and ethanol?
all in the ventral striatum
what is the effect of autoreceptors on impulsivity?
the lower the level of auto-receptors, the higher the dopamine release, the higher the impulsivity seen, so dopamine is linked to impulsivity
what is the effect of dopamine on pleasure?
it has no effect
what is the effect of dopamine on incentive salience/reward seeking?
dopamine is required for incentive salience/reward seeking, depleting dopamine results in drug use (except in cigarette use)
why are pharmacotherapies for SUD targeting DA not enough?
does have an effect on reward seeking but no DA effect on pleasure or use of easily available drug (will not seek it but if it is there, they will take it)
