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
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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Chemical Signaling in the Nervous System
Figure 6-2
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Release of Neurotransmitter Molecules
Figure 6-3
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6 Neurotransmitters Related to Drug Effects
The 3 Monoamines
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
6 Neurotransmitters Related to Drug Effects
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
Norepinephrine - important in the regulation of hunger,
alertness and arousal; implicated in depression
6 Neurotransmitters Related to Drug Effects
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)
Endorphins - thought to modulate pain relief and to be
associated with naturally occurring pleasures or “highs”
GABA - referred to as an inhibitory transmitter because when it
binds to receptor sites it stops the neuron from firing
What drugs do you think act on the GABA system?
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
- receptor activation; drug mimics neurotransmitter
- receptor blocking
The 4 major routes of drug administration

Oral

Injection
subcutaneous - beginning drug users; steady
absorption rate
intramuscular - faster but obviously can be
painful
intravenous - into veins; “mainlining”; immediate
effects but most complications
(e.g. death)
The 4 major routes of drug administration

Inhalation - absorbed through lungs; fast & effective;
drug gets wasted though, can only absorb a
small amount

Absorption
intranasal - mucous membranes of nose, sinus
sublingual - under the tongue; absorbed through
mouth’s mucous membranes
(e.g nitroglycerin; dip or chew
tobacco to get nicotine)
transdermal - through the skin; examples?
(nitro and nicotine patches)
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? Brain, liver, heart)
 Elimination: liver enzymes play biggest part in expelling
drugs; kidneys as well
 where excreted? Urine, feces, perspiration,
mother’s milk, lungs
 drug half-life: time it takes for 50% of drug to be
excreted
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
•
•
the diff b/n ED and LD MAY NOT BE THAT LARGE!
drug interactions
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. alcohol and depressant drugs
• tolerance to some effects of drug but not others
(EX. Appetite suppressant effect of amphetamine absent after few weeks)
• tolerance syndrome doesn’t develop to some drugs
(Ritalin?)
•
reverse tolerance - becoming more sensitive with repeated
use (amphetamine; pot?)