Pinel basics ch13

Copyright © 2007 by Allyn and Bacon

Chapter 13 Health Psychology: Addiction, Emotion, and StressImpact of Psychological Factors on HealthThis multimedia product and its contents are

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Health Psychology

An area of psychological research that focuses on the effects of psychological factors on physical health

Multidisciplinary Two major areas addressed here –

addiction and emotion


Drug Tolerance

Decreased sensitivity to a drug as a consequence of exposure to it Shift in the dose-response curve

Cross tolerance – exposure to one drug can produce tolerance to similar drugs

Tolerance often develops to some effects and not others

More than one form of tolerance



Drug Tolerance

MetabolicLess drug is getting to the site of action

FunctionalDecreased responsiveness at the site of

action - fewer receptors, decreased efficiency of binding at receptors, receptors less responsive


Physical Dependence

Indicated by occurrence of withdrawalSeen when drug use is terminatedSymptoms are the opposite of the drug’s

effectsBody has made changes to compensate for

drug’s presence – functions normally with the drug present

Severity varies with drug and pattern of use



Drug Tolerance and Conditioning

Situational specificity of drug tolerance is well-documented

Cues associated with drug-taking become conditioned stimuli that elicit conditioned compensatory responses, producing tolerance prior to drug use or withdrawal in the absence of the drug



Addiction: What Is It?

“Addicts” are those who continue to use a drug despite its adverse consequences

Nobody is immune to the addictive effects of drugs


Biological Theories of Addiction

Physical-Dependence Theory – Use continues to avoid withdrawal

Why relapse after detoxification? Why begin use? Why does addiction develop to drugs that do not

produce severe withdrawal? Positive-Incentive Theories

Use continues due to craving (anticipated pleasure) for drug effects

Supported by research


Causes of Relapse

Stress Drug use as a coping mechanism

Priming A single exposure leads to a relapse

Environmental cues


5 Commonly Abused Drugs

Tobacco Alcohol Marijuana Cocaine Opiates


Tobacco

Nicotine – major psychoactive ingredient About 70% of those who experiment with

smoking become addicted Only about 20% of attempts to stop are

successful


Effects of Long-Term Tobacco Use

Smoker’s syndrome – chest pain, labored breathing, wheezing, coughing, increased susceptibility to respiratory infections

Susceptible to various lethal lung disorders – pneumonia, bronchitis, emphysema, lung cancer


Alcohol

A depressant High heritability estimate for alcohol

addiction - ~55% Metabolic and functional tolerance

develops Attacks almost every tissue in the body


Effects of Chronic Alcohol Consumption Severe withdrawal – 3 phases

5-6 hrs post-drinking: tremors, nausea, sweating, vomiting, etc.

15-30 hrs: convulsive activity24-48 hrs: delirium tremens – may last 3-4

days Korsakoff’s syndrome Cirrhosis


Fetal Alcohol Syndrome (FAS)

Alcohol readily penetrates the placental membrane

Alcohol disrupts brain development No known “safe” amount


Marijuana

Cannabis sativa – common hemp plant THC – primary psychoactive constituent –

although over 80 others are present High doses impair short-term memory and

interfere with tasks involving multiple steps Addiction potential is low Negative effects are far less severe than

those associated with alcohol and tobacco


Adverse Effects of Heavy Marijuana Use

Respiratory problems – cough, bronchitis, asthma

Single large doses can trigger heart attacks in susceptible individuals

No evidence that marijuana causes permanent brain damage


Medicinal Uses of Marijuana

Treat nausea Block seizures Dilate bronchioles of asthmatics Decrease severity of glaucoma Reduce some forms of pain


THC

Fat-soluble Binds to receptors in basal ganglia,

hippocampus, cerebellum, and neocortex

Endogenous ligand is anandamide Function of anandamide is not known


Stimulants

Increase neural and behavioral activity Cocaine and its derivatives – commonly

abused Crack – a potent, cheap, and smokable

form of cocaine Cocaine is an effective local anesthetic

Synthetic analogues procaine and lidocaine used today


Cocaine

Cocaine binges or sprees may lead to cocaine psychosisLooks like paranoid schizophrenia

While tolerance may develop to some effects of cocaine, sensitization is seen to motor and convulsive effects

Although highly addictive, withdrawal is relatively minor


Amphetamine

AKA “speed” – another abused stimulant Effects are comparable to those of cocaine

– also can produce psychosis MDMA (ecstasy) – a relative of

amphetamine Evidence suggests that stimulants are

neurotoxins


Ecstasy (MDMA)

Studies of lab animals find that MDMA has toxic effects on serotonergic and dopaminergic neurons

But are the doses used in studies comparable to what humans use?

Human studies do find abnormalities of serotonergic function and deficits in memory, mood, and psychomotor tasks


Opiates: Heroin and Morphine

Morphine and codeine obtained from the opium poppy

Opiates – these drugs and others with similar structures or effects

Medicinal uses Analgesics (painkillers) Treatment of cough and diarrhea

High risk of addiction


Factors Increasing Opiate Popularity China’s ban of tobacco smoking led to

opium smokingMore addicting than eating opium

Isolation of morphine Opium’s most potent constituent

The hypodermic needleDuring the Civil War morphine addiction came

to be known as “soldiers’ disease”


U.S. Opiate History

Readily available in a variety of “potions” until 1914

Harrison Narcotic Act (1914) Illegal to sell or use opium Heroin, a synthetic opiate, was still legal

Structure similar to morphine, but better able to cross the blood-brain barrier

More addictive Heroin illegal as of 1924


Opiate Addiction

Drawn to use by the rush following IV injection Tolerance and physical dependence develop Desire to avoid withdrawal adds to motivation to

use Although highly addictive, direct health hazards

are relatively minor Many health hazards related to use of needles Severity of withdrawal has been exaggerated



Comparison of the Health Hazards

Which drug is our biggest “drug problem”?

Which drug harms the individual the most?

Which drug harms society the most?


Addiction and the Neural Mechanisms of Motivation

How has drug-produced reinforcement been studied in nonhumans?Drug self-administrationConditioned place-preference


Behavioral preference tests


Involvement of Dopamine in Drug Addiction Dopamine antagonists

block self-administration of, or conditioned preference for addictive drugs

reduce reinforcing effects of food Dopamine might signal

reward/pleasure


The Dopamine (DA) System

Cell bodies of neurons composing the brain’s DA system are in two midbrain nucleiSubstantia nigraVentral tegmental area

Two mesotelencephalic DA pathwaysProjecting from the midbrain to areas in the

telencephalon


Mesotelencephalic Dopamine System Nigrostriatal pathway

Substantia nigra > Dorsal striatumDegeneration here seen in Parkinson’s

Mesocorticolimbic pathwayVentral tegmental area (VTA) > cortical and

limbic sites Involved in reward – VTA > nucleus

accumbens



Evidence of Dopamine’s Role in Reinforcing Effects of Drugs Lab animals will press a level to self-administer

addictive drugs to the nucleus accumbens Lab animals will develop conditioned place

preferences with microinjections of addictive drugs to the nucleus accumbens

Addicts only report a high when cocaine is effectively blocking DA reuptake, increasing extracellular dopamine

IV amphetamine study – euphoria reported correlated with DA levels in nucleus accumbens


Human Studies

PET studies find that many addicts have reduced cerebral dopamine levels

Dopamine levels increase when addicts are exposed to their drug of choice

Dopamine may be involved in the expectation of reward, rather than its experience – a signal, perhaps


Expectation-of-reward Theory

Dopamine neurons in monkey VTA – respond to unpredicted reward

An expected reward did not lead to a release of dopamine

A conditioned stimulus does lead to release of dopamine

Consistent with dopamine as a signal of a reward to come, as opposed to a response to a reward


Introduction of the Biopsychology of Emotion Phineas Gage provides an elegant

demonstration of the brain’s role in emotion

Why would a tamping iron through the skull lead to dramatic changes in personality?

Damage to the medial prefrontal lobes


Darwin’s Theory of the Evolution of Emotional Expression

Expressions of emotion evolve from behaviors that indicate what an animal is likely to do next

If emotional signals are beneficial, they will evolve to more effectively communicate and may lose their original meaning


Evolution of Emotional Expression Opposite messages are often

signaled by opposite movements. “Principle of antithesis”

Threat displays, for example, are beneficial – intimidate victims without the costs and risks of fighting


Theories of Emotion

James-Lange Stimulus > autonomic/skeletal response > emotion Autonomic/skeletal response necessary for emotion

Cannon-Bard Stimulus > autonomic/skeletal response & emotion Autonomic/skeletal response independent of emotion

Both of these extreme positions are wrong


Theories of Emotion


Bard – Sham Rage

Decorticated cats exhibit extreme and unfocused aggressive responses

Hypothalamus must be intact Perhaps hypothalamus is needed for

expression of aggression and cortex serves to inhibit and direct responses

Papez proposed emotional circuit – limbic system, that includes hypothalamus



Kluver-Bucy Syndrome

Rare cerebral neurological disorder Major symptoms - urge to put objects

into mouth, memory loss, extreme sexual behavior, placidity, visual distractibility

Bilateral temporal lobes


Stress and Health

Stress – reaction to harm to threat Stressors – stimuli that cause stress Chronic psychological stress – most

clearly linked to ill health In the short-term stress is adaptive, in

the long-term it is maladaptive


Selye and the Stress Response

Activation of the anterior-pituitary adrenal-cortex system

Selye neglected the role of the sympathetic nervous system

All common psychological stressors are associated with high levels of glucocorticoids, epinephrine, and norepinephrine


Effects of Stress


Stress and Gastric Ulcers

Gastric ulcers – lesions of stomach lining and duodenum

More common in those who are stressed and readily created in the lab

Ulcers are caused by a bacteria – but it appears that stress makes the body susceptible to this bacteria

75% of healthy subjects have the bacteria


Psychoneuroimmunology

Study of the interaction of psychological factors, nervous system, and immune system

Antigens – cell proteins that identify them as native or foreign

Immune system protects with specific and nonspecific barriers


Immune System

Nonspecific barriersMucous membranesPhagocytosis – consume and destroy foreign

matter Specific barriers

Cell-mediated (T lymphocytes)Antibody-mediated (B lymphocytes)

Lymphocytes – white blood cells



Stress and Immune Function

If stress affects immune function, how might it do so?

Why is stress initially adaptive and then, when chronic, harmful?


Meta-Analysis of Stress Studies

Effects of stress on immune function depend on the kind of stressAcute stressor improve immune functionChronic stressor impair

Many ways that stress could impact immune functionPhysiological Behavioral


Why might decreased immune function not cause an increase in disease?

Redundancy exists in the immune system

Stress-produced immune changes in test subjects may be too short-lived to have any impact

Declines in some aspects of immune function may lead to compensatory increases in others


Early Experience of Stress

Early exposure to stress may result in increased intensity of subsequent stress responses

While prenatal stress has a negative effects, early neonatal stress can have lasting positive effect – if the stress leads to increased maternal grooming


Stress and the Hippocampus

Hippocampus has many glucocorticoid receptors

Following stressDendrites of pyramidal cells are shorter and

less branchedAdult neurogenesis of granule cells reduced

Effects seen with only a few hours of stress


Brain Mechanisms of Emotion

What can fear conditioning tell us about the brain’s role in emotion?

What does the amygdala do for us?


Fear Conditioning

Auditory fear conditioning blocked with medial geniculate nucleus (MGN) lesions – not affected by auditory cortex lesions

Critical pathways: MGN to amygdala Amygdala lesion blocks fear

conditioning


Auditory Fear Conditioning


Contextual Fear Conditioning and the Hippocampus Just as fear of an auditory stimulus can be

learned, so can fear of a place Hippocampus involved

Lesion before conditioning prevents development of contextual fear

Lesion after blocks retention of contextual fear response

Other fear responses intact


Role of the Amygdala is Human Emotion Structure most frequently associated with

emotionKluver-Bucy syndromeStudy of those with amygdalar damage

Damage > problems with recognition of facial expressions of fear

Urbach-Wiethe – bilateral amygdala damage > unable to identify fear


Emotion

What unique challenges must be overcome in the study of emotion?

Why is it important to develop an understanding of the brain mechanisms that underlie emotion?

Pinel basics ch13

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