Drug Addiction Flashcards
DSM- 5 substance- related + addictive disorders
- Alcohol, caffeine, tobacco , cannabis
- Alcohol related disorders- criteria A:
- problematic pattern of alcohol leading to clinically significant impairment / distress - 2 of the following occur within 12 months
- persistent desire / unsuccessful effects to cut down
- lots time spent obtaining alcohol/ recover
- recurrent alcohol use
- Tolerance
- withdrawal
Neuropsychology - Mesolimbic Dopamine system
- ventral tegmental area projects to nucleus accumbens via mesocortical dopamine projection
- VTA projects to medial prefrontal cortex via mesoaccumbens dopamine projection
Electrical Brain stimulation
- Mispositioned electrode probe in region that passes the medial forebrain bundle ( mfb)
- Mfb is major highway from neural tracts including mesoaccumbens dopamine projection
- Rats induce electrical current in Mfb region themselves (intracranial self- stimulation)
- Olds found rats constantly pressed button for brain stimulation ( activates mesolimbic dopamine system)
Electrical brain stimulation in humans - Bishop et al
- intracranial self-stimulation reinforced in humans
- show tray of food to hungry people
- Didn’t want to stop brain stimuIation even for food - addicted
Mesoaccumbens dopamine + reward
- Dopaminergic activation in striatum correlates with self- reported high
- cocaine activates nucleus accumbens (releases dopamine)
chronic Drug use - striatal impact
- Daley et al
- PET scans shows reduced dopamine receptors in cocaine addicts
smoking + accumbens dopamine function
- Weirs et al
- smoking reduces number of D 2 dopamine receptors + dopamine release
cocaine + grey matter volume
- Franklin et al
- reduced frontal grey matter volume in cocaine addicts
conditioning + dopamine - Pavlov
- mesoaccumbens dopamine projection modulates efficacy of conditioned stimulus
- dopaminergic activation in nucleus accumbens following repeated presentation of reward cues
- reward cues ( conditioned stimulus) can produce a large activation nucleus accumbens + dopamine release
conditioned drug effects
- Robinson , Berridge + Alderige
- drugs are addictive because activate mesoaccumbens dopamine projection = drug - associated stimuli to acquire conditioned properties
- re-exposure to drug- associated stimuli at a later date activates memories of drug = craving
pharmacological treatments
- Nicotine : patches/gum - maKes withdrawal + craving more manageable (don’t get hit when you have a cig)
- Opiates: methadone - mild, non-high inducing version of heroin - prevents withdrawal + craving
- Alcohol: Antabuse- inactive till alcohol consumed then causes nausea + dizziness
Extinction Therapy
- repeat presentation of Pavlovian conditioned stimuil elimilate conditioned response ( dopamine release)
Psychological treatment
- Heroin addicts cue exposure followed by extinction therapy eased craving response
Effects Marijuana
- relaxed + sociable
- large dose = rapid shift in emotion, impaired memory
- Extremely heavy dose = hallucinations
- can interfere with cog functioning
Physical consequences of Marijuana
- short term= bloodshot + itchy eyes, dry mouth , increased appetite+ raised blood pressure
- long term can impair lungs
- regular user fMRI scans show different patterns of connectivity between amygdala + cortex when reg neg emotions
- Tolerance + withdrawal symptoms = restlessness , depression + anxiety
Effects of opioids
- euphoria, drowsiness + lack of coordination
- stimulates neural receptors of body own opioid system
- users develop tolerance + withdrawal
- withdrawal = muscle pain/ twitching , sneezing, sweating , chills
stimulants
- act on sympathetic nervous system to increase alertness + motor activity
Stimulants- Amphetamines
- Heighten wakefulness , inhibit intestial function increases heart rate
- Higher dose = agitated , nervous + confused
stimulants - methamphetamine
- cravings are strong and last hours
- feelings euphoria, increased blood flow + body temp
- High comes crashing down + become agitated
- Associated with reduced brain volume in temporal + frontal corticals (reward + decision making)
stimulants - cocaine
- Blocks reuptake of dopamine in mesolimbic areas
- over dose = chills, nausea, insomnia
- chronic use = impaired relationships , paranoid thinking
LSD + hallucinogens
LSD- tolerance develops rapidly, sharp mood swings
- exert effects by serotonin system
Ecstacy + PCP
- contains hallucinogens + amphetamines
- contributes to release + reuptake of serotonin
- Neurotoxic effect on serotonin system
- enhances intimacy + improves relationships + self confidence
- causes muscle tension, rapid eye movement, nausea
- PCP more severe effects : paranoia, violence + death