Addiction

• tolerance
• withdrawal
• "compensatory mechanisms" in brain (see Figure 19.2)

• positive
• negative

• D3 receptors in nucleus accumbens
• Increased sensitivity after drug use

• Stress triggers release of dopamine in nucleus accumbens
• Priming effect

• death from heroin often associated with "bad batch"
• classical conditioning to environment and drug-taking behavior

• periaqueductual gray - produce analgesia
• preoptic area - produce hypothermia
• reticular formation - produce sedation
• ventral tegmental area and nucleus accumbens - produce reinforcement

• both act as dopamine agonists by preventing reuptake
• amphetamine also directly stimulates release of dopamine
• Crack most effective reinforcer of all drugs, as gets quickly to brain when smoked
• rats are more likely to die from self-administration of cocaine than heroin
• amphetamine psychosis usually subsides, but may make person more susceptible to its reoccurence

• nicotine acts on acetylcholine receptors (remember "nicotinic"?) and also increases the activity level of dopaminergic neurons which contain these receptors
• "cross priming effect" may occur with other drugs which activate dopamine systems

• caffeine prevents destruction of second messengers, acting as an agonist

• results in greater costs to society than any other drug
• leading cause of mental retardation in Western world
• study found very high incidence of fetal alcohol syndrome (40%) on native american reservation in Canada

• provides both positive and negative reinforcement
• antagonist developed which makes one sober, but has liability issues
• effects of alcohol and barbiturates are addditive, although barbiturates do not involve dopaminergic systems

• MZ twins more likely to be alike in alcohol abuse than DZ twins
• may have found gene responsible for dopamine receptor development that is related to alcoholism
• alcohol-preferring rats found to have lower levels of serotonin and dopamine

• Steady drinkers
• Binge drinkers

• associated with antisocial personality disorder
• adopted men whose biological fathers were steady drinkers were 7 times more likely to be steady drinkers themselves
• daughters of steady drinkers more likely to develop somatization disorder
• likely drink for the positive reinforcement effects

• having a biological parent who was a binge drinker results in the development of binge drinking only if the child also is exposed to alcohol in the family environment
• likely drink for the negative reinforcement effects