Transcript CHEMICAL MESSENGERS

MODELS OF ADDICTION:
A SUMMARY
Moral / Temperance Model *
Addiction as Sin or Crime
Personal Irresponsibility
Disease Model *
Genetic and Biological Factors
12-Step Framework; Abstinence
Education as Treatment
Behavioral and CognitiveBehavioral Models *
Conditioning and Reinforcement
Social Learning and Modeling
Drug Expectancies and other
Cognitive Factors / RP
Family Models
Family Disease
Family Systems
Behavioral Marital/Family Tx
MODELS OF ADDICTION:
A SUMMARY
Psychological / Psychoanalytic
Disordered /Addictive Personality
Sociocultural Models
Cultural Factors
Socioeconomics/ Social Policy
Drug Subcultures
Public Health Model
Agent, Host, Environment
Interactions
THE BIOPSYCHOSOCIAL MODEL:
AN INTEGRATION
Medical / Disease
Models of Addiction
BIOLOGY OF ADDICTION
• Introduction
• Why study addiction from a biological perspective?
All Multicell Organisms Require Cellto-Cell Communications
Mammals Require a Variety of
Sophisticated Systems for Chemical
Communications
CHEMICAL MESSENGERS
 Chemical Messengers
 Hormones—Released from glands and
affect other cells, including other glands
 Neurotransmitters—More discrete and
targeted than hormones
 Receptors—Cell structures that receive
the chemical message
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Information Movement in the Nervous System
Figure 6-4
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Chemical Signaling in the Nervous System
Figure 6-2
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Release of Neurotransmitter Molecules
Figure 6-3
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7 Neurotransmitters Related to Drug Effects
The 3 Monoamines
1. Dopamine - common and pervasive chemical important in
regulation of motor movements, emotional and cognitive
processes, and reinforcement
- schizophrenia (increased dopamine activity)
- Parkinson’s Disease (decreased activity)
• Different drugs affect dopamine levels in different ways:
 stimulants like cocaine and amphetamines
increase dopamine activity
7 Neurotransmitters Related to Drug Effects
2. Serotonin - important in regulation of sleep and mood
monoamine theory of depression supported by:
drugs that reduced Monoamines produce depression
drugs effective in treating depression act on serotonin
or norepinephrine
3. Norepinephrine - important in the regulation of hunger,
alertness and arousal; implicated in depression / mood
regulation
7 Neurotransmitters Related to Drug Effects
4. Acetylcholine (ACh) - important in the functions of muscular
activity, regulation of thirst and memory
(e.g. Alzheimer’s Disease is related to loss of cholinergic
function in brain)
5. Endorphins - thought to modulate pain relief and to be
associated with naturally occurring pleasures or “highs”
6. GABA - (gamma-aminobutyric acid) referred to as an inhibitory
transmitter because when it binds to receptor sites it stops the
neuron from firing.
What drugs act on the GABA system? ____________
7. Glutamate – throughout brain; excitatory
BIOLOGY OF ADDICTION
• neuron is like a rechargeable battery, can fire again after
either:
enzymes break down transmitter substance so it cant
occupy receptor site anymore or
reuptake: substance taken back into terminal button
•
agonists and antagonists
agonist is any chemical (naturally occurring in brain or
introduced) that fits a receptor lock and activates it;
in general, agonists increase the activity of the
transmitter systems they operate on
(ex. morphine is an agonist for the endorphins )
BIOLOGY OF ADDICTION
antagonists - don’t activate receptor sites and neurons to fire
but still occupy site, preventing other chemicals
from sitting there
ex. naloxone is an opiate antagonist
Some
Mechanisms of
Drug Action
- drug can decrease or
increase synthesis of
neurotransmitters
- neurotransmitter
transport interference
- neurotransmitter
reuptake is blocked
(pictured)
- receptor activation;
drug mimics
neurotransmitter
- receptor blocking
NEURAL BASIS OF REWARD & ADDICTION
• studies of stimulation of rat brains:
• There is possibly a final common pathway for positive
stimulation and reward; this pathway is dopamine-rich;
• most drugs produce changes in this system, but “broccoli”
(food) does not produce dramatic changes…
Why not?
NEURAL BASIS OF REWARD & ADDICTION
 “body” and brain memories…
amygdala activated prior to drug ingestion in cocaine
users compared to controls
 “addicted brain” is qualitatively different from non-drug users
even after drug use is discontinued
e.g. _____________________________
A Few Definitions
Psychopharmacology - study of the effects of drugs on behavior
Pharmacology -
the study of drugs and their effects;
• Pharmacokinetics - the study of how drugs are absorbed,
distributed, transformed and excreted in animals and humans
• Pharmacodynamics - study of the biochemical effects of drugs
and their mechanisms of action
Brainstorm
What factors relate to the way drugs affect
us?
Brainstorm
Drugs need to get into the body before
exerting an effect...how many different
ways can drugs enter the body and brain?
The 4 major routes of drug administration

Oral

Injection
subcutaneous intramuscular intravenous -
The 4 major routes of drug administration

Inhalation - absorbed through lungs…

Absorption
intranasal - mucous membranes of nose, sinus
sublingual - under the tongue; absorbed through
mouth’s mucous membranes
transdermal - through the skin; examples?
rectal - suppositories
Pharmacokinetics
 Absorption: rate and extent to which drug leaves its site
of administration;
bioavailability: portion of drug that reaches its site of action
 Distribution: where the blood flows most is where most
of the drug goes (where? _________)
 Elimination: liver enzymes play biggest part in expelling
drugs; kidneys as well
 where excreted? _______________________
 drug half-life: ___________________________
Pharmacodynamics
 dose-effect curve
effective doses - % of people who experience
effect of drug at given doses
 ED - 50 ; 50% of people taking specific dose
will be experiencing the effect
lethal doses - effect of interest is death! Defined
as % of animal subjects who die
LD - 50
•
Major Implications: _____________________________
____________________________________________
Behavioral Pharmacology and Tolerance
Behavioral Pharmacology - specialty area within pharmacology
that concentrates on drug use as learned behavior
General Definition of tolerance - reduced response to a drug after
repeatedly taking it
Types of Tolerance:

Dispositional tolerance - increase in the rate of
metabolizing a drug after repeated use

Functional (cellular) tolerance- brain becomes
less sensitive to drug
• acute tolerance: occurs within single dose or first few
doses of drug
(e.g., Alcohol
cocaine)
• vs. protracted:occurs after regular,chronic use
Behavioral Pharmacology and Tolerance
• Behavioral tolerance - person adjusts or compensates for
their drug-induced behavior
EX. We compensate for intoxicated behavior in diff ways
_______
• Issue of cross-tolerance EX. ________________________
• tolerance to some effects of drug but not others
• tolerance syndrome doesn’t develop to some drugs
•
reverse tolerance - becoming more sensitive with repeated
use (examples ?)