Brain, Behavior, and Experience Ch 5

Psychoactive drug

Drugs that have psychological effects, such as anxiety relief or hallucinations.

Drug

Any substance that changes the body or its functioning

Affinity

Binds to neurotransmitter

Efficacy

Binds and activates neurotransmitter

Agonists

Mimics or enhances a neurotransmitter

Antagonists

May reduce release of neurotransmitter or block receptors

Addiction identified by

Preoccupation with obtaining a drug, compulsive use of the drug in spite of adverse consequences, a high tendency to relapse after quitting.

Withdrawal

Negative reaction that occurs when drug use is stopped

Tolerance

Person becomes less responsive to the drug, requiring increasing amounts of the drug to produce the same results.

Significant reason for overdose

Tolerance

Opiates types

Analgesic: pain relief, endorphin: agonists, hypnotic: sleep-inducing, euphoria: strong feelings of happiness.

Opiates suppress what brain structure

Medulla

Depressants types

Sedation: calming, reduces agitation and irritability, GABA agonists, Anxiolytic: anxiety reduction, Hypnotic: sleep inducing

Stimulants

Increases arousal and alertness. Monoamine agonists: serotonin, dopamine, norepinephrine, epinephrine. Euphoria

Psychedelics

Perceptual distortions and hallucinations. Serotonin agonists.

Marijuana

Temporary memory, cognitive, and IQ deficits. Impaired prefrontal functioning. Anandamide agonists.

Opiates abuse potential

High abuse potential due to mimicking endogenous opioids (endorphins). Ex- Morphine, heroin synthesized from morphine, oxycontin.

Why is heroin dangerous

Produces intense euphoria, crosses the blood brain barrier, tolerance develops rapidly.

Learned association

Tolerance and environment it develops. When drug is taken in a different setting, it is more likely to result in an overdose.

Endorphins

Produce pain relief by stimulating these opioid receptors. Produce additional positive effects by indirectly stimulating dopamine pathways.

Fentanyl

Purely synthetic opiate. Chemical. Easy to transfer. Small amount for effect.

Depressants

Drugs that reduce nervous system activity.

Commonly used and abused depressant

Alcohol (ethanol). Used throughout history in cultural and social practices.

Alcohol effects on behavior

Stimulant by turning off cortical inhibition, reducing social constraints and anxiety. Higher doses produce sedative and hypnotic effects.

Negative effects of alcohol

Acute effects include alcohol-induced coma or death. Chronic effects include liver damage and brain damage associated with Korsakoff’s syndrome.

Withdrawal dangerous effects

Produce a condition known as delirium tremens. Hallucinations, delusions, confusion, and in extreme cases, seizures and possible death.

Alcohol effects on neurotransmitters

Inhibits glutamate (excitatory transmitter). Part of the GABA_A receptor complex (inhibitory effects). Effect is sedation, anxiolytic, muscle relaxation, and inhibition of cognitive and motor skills.

Why does alcohol have pleasurable effects

Stimulation of opiate, serotonin, and cannabinoid receptors.

Barbiturates

Previously drug of choice for treating anxiety and insomnia. Prescribed doses not addictive, but tolerance may lead to increased consumption. Can open chloride channels without GABA.

Benzodiazepines

Safer drugs for treating anxiety. Effects due to decreased activity in the limbic system, hippocampus, brain stem, and cortex.

Stimulants

Activate CNS to produce arousal, increased alertness, relieves fatigue, decreased appetite, and elevated mood.

Monoamine

Agonist. Indolamine (serotonin). Catecholamine (dopamine, norepinephrine, epinephrine)

Cocaine

Extracted from coca plant. Blocks dopamine and serotonin reuptake. Dopamine removes inhibition on lower structures. Serotonin, dopamine, norepinephrine, epinephrine agonist.

Ritalin

Stimulant with methylphenidate. Blocks reuptake of dopamine and norepinephrine.

Cocaine safeness

Believed to be safe. Freud initially endorsed use. Users have deficits in executive functions that involve the pre-frontal cortex.

Cocaine addictive

Due to intense euphoria and craving during abstinence. Difficult to treat because many users have comorbid conditions.

Amphetamines

Group of synthetic drugs that produce euphoria and increase confidence and concentration. Ex- Benzedrine, Dexedrine, and methamphetamine. Increases the release of norepinephrine and dopamine. Heavy use can cause symptoms that resemble schizophrenia. Have been used in weight-loss drugs, to postpone sleep, and treat narcolepsy.

Nicotine

Primary psychoactive and addictive agent in tobacco. Stimulates nicotinic acetylcholine receptors (Acetylcholine agonist). In periphery, activates muscles and may cause twitching. Centrally, produces increased alertness and faster response to stimulation.

Nicotine withdrawal

Symptoms are mild, but contribute to a 7% increase in workplace accidents during the United Kingdom’s No Smoking Day. Only 20% of attempts to stop are successful after 2 years.

Smoking dangers

Compounds in tobacco smoke: various cancers, Buerger’s disease, reduced birth weight. Smoking is the primary cause of preventable death in the world. 480,000 premature deaths annually in the U.S.; 6 million worldwide.

Caffeine

Produces arousal, increased alertness, and decreased sleepiness. Adenosine antagonist. Blocks receptors for the neuromodulator adenosine, increasing the release of dopamine and acetylcholine. Because adenosine has sedative and depressive effects, blocking its receptors contributes to arousal.

Caffeine withdrawal symptoms

Headaches, fatigue, anxiety, shakiness, and craving.

Psychedelics

Compounds that cause perceptual distortions. Hallucinogenic. Light, color, and details are intensified. Objects may change shape, sounds may evoke visual experiences, and light may produce auditory sensations.

Psychedelics examples

LSD, mushrooms, mescaline, PCP, ecstasy

Ecstasy (MDMA)

Popular among young people. Psychomotor stimulant at low doses (releases dopamine). Hallucinatory at higher doses (releases serotonin). Chronic use may cause impairment in serotonin functioning. Cognitive deficits such as memory loss. Monkeys- destroys serotonergic neurons.

Marijuana

Dried leaves and flowers of Cannabis sativa

Delta-9-tetrahydrocannabinol (THC)

Binds to endogenous cannabinoid receptors. Cannabinoids regulate presynaptic transmitters. (Anandamide agonist)

THC effects

Mildly addictive, memory, cognitive, IQ deficits, hippocampus, amygdala reductions, impaired prefrontal functioning in offspring when smoked during pregnancy.

Independent processes

Addiction and withdrawal. They occur in different parts of the brain.

Rats in addiction

Self-inject morphine into the ventral tegmental area, which indicates the area is involved in addiction. However, blocking opiate receptors there does no produce withdrawal. No press into periventricular gray, not involved in addiction, but blocking those opiate receptors will produce withdrawal.

Dopamine system

A hypothesized basis for addiction is reward. The positive effect an object or condition (drug, food, sex, etc.) has on the user. The mesolimbic-cortical dopamine system is considered the major reward system. Implicated in the rewarding effects of drugs, food, sex, and electrical stimulation of the brain (ESB)

Paraldehyde system

Hypo frontality- reduced activity in frontal regions. Creates impulsivity and compulsivity. Stopping the drug activates neurons in the amygdala. Mediate fear and other aversive states, producing the negative emotions and many of the bodily symptoms that characterize withdrawal.

Chronic exposure to abused drugs

Baseline levels of dopamine activity decrease in the system. Tolerance and decreased response to normal rewarding stimuli. But, the drug/drug-related stimuli produce greater increases in dopamine. This sensitization can last long after the person stops taking the drug.

Addiction in learning

Produces brain changes, creating lifelong addiction. Repeated use leads to enduring neural changes. Increased dendrite length and complexity in the nucleus accumbens.

Craving

Hyperactivity in areas involved in learned and emotion (hippocampus)

Agonistic treatments

Mimic the drug’s effects. Ex- methadone for opiate addiction. Serve as replacement for drug.

Antagonistic treatments

Block drug effects. Ex- naltrexone is used for opiate and alcohol addiction. Antagonistic treatments don’t replace the drug, so compliance depends on the addict’s motivation to quit.

Aversive treatments

Cause an unpleasant reaction when the addict uses the drug. Ex- antabuse (blocks the enzyme aldehyde dehydrogenase or ALDH) for alcohol addiction causes immediate hangover effects. Treatment compliance depends on the addict’s motivation to quit.

Anti-drug vaccines

Stimulate the immune system to make antibodies that degrade the drug. Reduced serotonin is found across several addictions. Drugs that potentiate serotonin have shown some usefulness.

Behavioral management stats

For heroin addiction has a 10-30% success rate; combined with methadone, success rises to 60-80%.

Pharmacological treatment controversy

Due to belief that recovery should involve the exercise of will and that it is wrong to give an addict another drug, such as methadone.

Drug treatment cost

Cost effective: addiction costs $600 billion a year in the U.S., but every dollar invested in treatment saves $7.

Type 1 alcoholism

Cautious and emotionally dependent, drinking began after 25, abstinence mixed with binge drinking. More environment, fewer genes.

Type 2 alcoholism

Impulsive, uninhibited, confident, socially detached, more likely male, bar fights, and reckless driving. Die earlier.

Genes with negative effects of alcohol

4X more likely to become alcoholic later. The inheritable ability to eliminate aldehyde is associated with alcoholism and vulnerability to other drugs. A genetic deficiency in the ability to metabolize nicotine protects some people from nicotine addiction.

Drug dependence with genes

A number of genes are common to drug dependence and the personality characteristics associated with it- impulsivity, risk taking, novelty seeking, and stress responsiveness.

Gene and addictions

Roughly 50% to addiction. Increase vulnerability, involved with neurotransmitter systems. Affect how the individual responds to the drug.

Environmental influences in addiction

Stress, social pressure, drug exposure

Genes in addiction with brain function

Increased high frequency EEG occurs in alcoholics and their offspring. Alcoholics and their offspring also show a reduction in the normal dip in the P300 wave. Not specific to alcoholism. Often occur in disorders characterized by behavioral disinhibition, such as conduct disorder, antisocial behavior, and other types of drug abuse.

Addiction in vulnerability and behavioral inheritance

Behavior results from an interplay between environment and genetics. It is not enough to assign relative roles to environment and heredity; we must then understand the mechanisms- the neurotransmitters, receptors, pathways, enzymes, an so on.