Download CHAPTER 16 Drug Abuse and Autism Basic Lecture Outline with

CHAPTER 16
Drug Abuse and Autism
Basic Lecture Outline with notes
Substance Abuse Disorders
Addiction
Latin roots from addicere “to sentence”
Physical vs. Psychological addiction
Physical dependence – “an adaptive state that manifests itself by intense
physical disturbances when the administration of the drug is suspended”
Tolerance – decreased sensitivity to a drug from continued use.
Withdrawal – opposite symptoms of the effects of the drug itself
Psychic dependence – “a condition in which a drug produces a feeling of
satisfaction and psychic drive that requires periodic or continuous
administration of the drug to produce pleasure or to avoid discomfort“.
Psychic dependence which is produced by stimulation of the nucleus
accumbens is far more powerfully “addictive” than some drugs that produce
physical dependence (Example: methamphetamine and cocaine produce
psychic dependence that is more “addictive” than heroin.)
Common Features of Drug Addiction
Positive Reinforcement – The faster the reinforcement after the drug is
used the more potent the reinforcement. Probably most significant reinforcer
is the release of dopamine in the nucleus accumbens. (Heroin is more
“addictive” or reinforcing than Morphine because it has a more rapid effect.)
Negative Reinforcement – Drug turns off or reduces an aversive stimulus.
(Alcohol reduces anxiety.)
Craving – Stimuli around the use of the drug create an excitement of the
brain and increase desire to use the drug, (example: the smell of the drug or
the place where drug is acquired or people one uses the drug with become
associated in the brain with drug use and create “craving” for the drug.)
Relapse – Use of the drug produces permanent changes in structure of the
brain, increased density of D3 receptors in nucleus accumbens, making more
likely that a person will reinstate drug use behaviors. Stress can also make a
person more vulnerable to drug use and reuse.
Commonly Abused Drugs
CNS Stimulants – elevate activity and alertness. They have an effect
similar to the body’s own adrenaline or epinephrine. Depending on the dosage
and type of CNS stimulant the effect range from increased alertness, felling
of well-being, euphoria, anxiety, palpitations, tremors, convulsions and
ultimately death.
Amphetamine and Cocaine – Newsweek August 8, 2005 – “Cops
nationwide rank methamphetamine the No. 1 drug they battle today:
in a survey of 500 law-enforcement agencies in 45 states released in
July by the National Association of Counties, 58 percent said meth is
their biggest drug problem, compared with only 19 percent for
cocaine, 17 percent for pot and 3 percent for heroin.” binds with and
deactivates the dopamine reuptake transporter proteins – thus
blocking the reuptake of dopamine after it is released by terminal
buttons. Amphetamine not only inhibit reuptake of Dopamine, but
also stimulates the release of Dopamine from the terminal buttons by
causing the uptake pumps to run in reverse. Both drugs also have
reinforcing effects on Dopamine receptors in the nucleus accumbens.
These drugs produce long term structural changes in brain.
Ritalin, Cylert –Used to treat ADHD or ADD. Although they are
chemically not amphetamine, pharmacologically their effect is
virtually identical.
Preludin – Prescribed as an appetite-suppressant. Tolerance to the
appetite-suppressant action appears with about two weeks. Then the
dose is increased.
Nicotine – Most commonly abused drug. Causes stimulation of
acetylcholine synapses. Because it stimulated the CNS at all levels,
including the cerebral cortex in produces increased levels of
behavioral activity. Increases the activity of dopaminergic neurons on
the mesolimbic system and causes dopamine to be released in the
nucleus accumbens and the ventral tegmental area.
CNS Depressants – Used as painkillers. Can also produce a feeling of
relaxation, loss of inhibition or euphoria in smaller doses. Act on the brain
like an anesthetic inducing drowsiness, sleep, loss of consciousness,
convulsions and ultimately death depending on the dosage. Use of CNS
depressants is ADDITIVE, can produce CROSS-TOLERANCE and CROSSDEPENDENCE
Alcohol – most heavily abused drug. Has effect on GABAa
receptors. Produces IPSPs, opening chloride channels, functioning as
indirect agonist. It also acts as an indirect antagonist on NMDA
receptors interfering with the effect of glutamate interfering with
spatial receptive fields within the hippocampus, thus affecting
memory and other cognitive functions. As with other addictive drugs,
alcohol stimulates an increased the activity of the dopaminergic
neurons of the mesolimic system and increases the release of
dopamine in the nucleus accumbens.
Opiates –Acts on GABAa and GABA b receptors. Natural or
synthetic morphine – major pain relieving agent obtained from opium
poppy. (Opiates – reduces pain and creates sense of euphoria.
Barbiturates – induce sleep but don’t reduce pain)
Cross – tolerance – tolerance to one opiate will also exhibit a
tolerance to all natural or synthetic opiates, even if they are
chemically dissimilar (example:
Morphine/Heroin/Demerol/Percodan )
Barbiturates – Acts on GABAa receptors as indirect agonist similar
to alcohol. Is not an analgesic. They are typically prescribed as
sedatives. If pain is present, however, they may have little sedative or
hypnotic effect.
General Anesthetics – Volatile hydrocarbons, capable of inducing
general anesthesia. Easily accessible(airplane glue, nail polish
remover, lighter fluid, hairsprays, paint thinner, room deodorizer,
laughing gas, and capable of inducing liver failure, nerve damage,
heart failure, respiratory arrest, coma and ultimately death.
Entactogens- “touching within” MDMA (Ecstasy). Produces a relaxed,
euphoric state. Sensations are enhanced and the user experiences heightened
feelings of empathy, emotional warmth, and self-acceptance. Does not
produce hallucinations. Releases serotonin into synapse by causing reuptake
pumps to work backwards, similar to the way cocaine and amphetamine
cause dopamine reuptake pumps to reverse. Prolonged use has causes
permanent neurotoxic damage in laboratory animals. There is speculation
this action is similar in humans, the result would be felt as depression with
the depletion of serotinergic neurons.
Heredity and Drug Abuse
“Most people who are exposed to addictive drugs – even drugs with high
abuse potential- do not become addicted.. The likelihood of addiction,
especially to alcohol and nicotine is strongly affected by heredity.’ Twp types
of alcoholics appear to exist: Steady drinkers and binge drinkers. Steady
drinkers usually begin drinking before age 25, are frequently unable to
abstain once they begin drinking, tend to be antisocial and novelty seeking
in their behavior. Binge drinkers on the hand, usually begin after age 25 and
tend to be psychologically dependent, repressed and guilt-ridden about
becoming alcohol dependant. Because of the cross-tolerant dependence many
addicts have, alcoholic who stop drinking tend to “abuse” caffeine and
nicotine excessively.
Therapy for Drug Abuse
Dsiulfiram (Antibuse) – Used to treat chronic alcoholism because it
inhibits aldehyde dehydrogenase, an enzyme that carries out a specific stem
in alcohol metabolism.
Methadone is used for heroin and morphine addiction. It has
approximately the same analgesic potency as morphine but induces less
euphoria
Naloxone– narcotic antagonists prevents euphoric effects of heroin or
morphine–used to treat narcotic dependence.
Autistic Disorder
Description
A chronic disorder first described in 1943 by Johns Hopkins psychiatrist Leo
Kanner, and again in 1944 by Austrian pediatrician Hans Asperger.
Symptoms include failure to develop normal social relations with other people,
impaired development of communicative ability, lack of imaginative ability and
repetitive, stereotyped movements.
*Signs of Autism
 no pointing by 1 year
 no babbling by 1 year; no single words by 16 months; no two-word
phrases by 24 months.
 Any loss of language skills at any time
 No pretend play
 Little interest in making friends
 Extremely short attention span
 No response when called by name; indifference to others
 Little or no eye contact
 Repetitive body movements, such as hand flapping rocking
 Intense tantrums
 Fixations on a single object, such as a spinning fan
 Unusually strong resistance to changes in routines
 Oversensitivity to certain sounds, textures or smells.
*Signs of Asperger’s
 Difficulty making friends
 Difficulty reading or communicating through nonverbal social cues,
such as facial expressions.
 No understanding that others may have thought or feelings different
from his or her own
 Obsessive focus on a narrow interest, such as reciting train schedules
 Awkward motor skills
 Inflexibility about routines, especially when changes occur
spontaneously
 Mechanical, almost robotic patterns of speech
*(Even “normal” children exhibit some of theses behavior from time to time. The symptoms of
autism and Asperger’s, by contrast, are persistent and debilitating.)
Prevalence
Until recently, autism was assumed to be rather rare. When Kanner first described it
the incidence was thought to be 1:10,000. When your book was written the incidence was
1:2,500. The latest studies suggest as many as 1:150 children may be affected by autism or a
related disorder, i.e. Asperger’s , Rett’s syndrome, Fragile X Syndrome
Heritability
Greater likelihood that two monozygotic twins (i.e. identical twins) will have autism is
70%.. The likelihood that two dizygotic twins (i.e. fraternal twins) is currently 0%. Genetic
investigations have suggest that genes involved in autistic disorder may be located on
chromosomes 2,7,15 and X.( Folstein and Rosen-Sheidley, 2001)
Papers published in “Molecular Psychiatry” indicate intense scrutiny is being given genes
that regulate the action of three powerful neurotransmitters: glutamate, serotonin, and
GABA. But those aren’t the only ones.
Your book also sites 20% of cases of autism have definable biological causes such as
rubella (German measles) during pregnancy, ;prenatal thalidomide; encephalitis caused by
the herpes virus, as well as autoimmune reaction provoked by streptococcal infection.
There is growing concern that toxins, such as mercury, and pollution in the environment
cal also lead to autism. (LA Times, Thursday, March 17, 2005, Section A10 “Possible
Mercury, Autism connection Found in Study” by, Maugh, Thomas H. II.
For several years there has been a controversy raging related to childhood vaccines and
mercury in the preservative, thimerosal that was used in the vaccines. There is also a theory
that autism stems from a severe immune reaction to something in the vaccine. So far, there
is no absolute proof, Some speculate the symptoms appearance shortly after the MMR
vaccine is coincidental. (Fifteen months is usually when the shots are given and is also the
time when maladaptive behaviors and dysfunctional speech patterns in babies are more
pronounced and thus, observed by parents.
Additional sources:
www.time.com
Time Magazine, May 6, 2002,”The Secrets of Autism” Nash, J. Madeline, Pp. 45-56.
http://www.nimh.nih.gov/publicat/autism.cfm
http://www.autism.org/overview.html
www.latimes.com