addiction

hypodermic syringe

developed in 1858, permitting purified substances to be injected directly into the blood stream

substance dependence

the more sever disorder, corresponds roughly to the notion of addiction

substance abuse

less severe disorder that may or may not lead subsequently to substance dependence

tolerance

decrease in potency with repeated administration of same dose

cross-tolerance

tolerance to one drug in a class confers tolerance to others in that class

dependence

withdrawal symptoms when drug use is terminated

addiction / substance dependence

persistent use, even in the face of physical, psychological, or social harm

positive reinforcement model

model that focuses on the ability of many abused drugs to serve as positive reinforcing stimuli

this means that consuming the drug strengthens whatever preceding behavior was performed by the organism

physical dependence model

once an individual has become physically dependent, attempts at abstinence lead to highly unpleasant withdrawal symptoms

relief from withdrawal symptoms promotes drug-seeking behavior through a process of negative reinforcement, leading to a behavioral loop of repeated abstinence and relapses

incentive sensitization model

a key feature is the distinction between drug liking (the high) and drug wanting (craving)

there is a marked increase in wanting the drug even though there is no change or even small decrease in drug liking

disease (medical) model

appears to be the most widely accepted model in our society

susceptibility and exposure models

susceptibility model

a medical model

addicts are born, not made

exposure model

a medical model

chronic drug use leads to alteration in the brain responsible for loss of control and the other key features of addictive behavior

mesolimbic dopamine system

activated by rewarding stimuli (food, sex) and addictive drugs (cocaine, amphetamines, alcohol)

hippocampus and amygdala

responsible for memories of ‘pleasure’

people, places, and activities associated with use

prefrontal cortex

impairments mediate long-term changes involved in loss of control, relapse

hypofrontality

reduced activity of frontal cortical structures, develops with chronic drug use

makes it more difficult to control stress and other executive functions