Biology, Behavior, and the Brain:
Methamphetamine Addiction
Methamphetamine is a powerful drug, roaring through our reservations at an alarming rate of "speed.” Maybe you've seen a movie that depicts some of the paranoid behaviors of a meth addict, or maybe there's someone from your own life experience who has used crystal meth. I know that has been true in my life. Though we may have seen the outward effects of crank use, most of us have no idea how this deadly, persuasive menace affects us at a biochemical level.
Classified by the scientific
community as a psychomotor stimulant, methamphetamine acts as a chemical
messenger in the sympathetic nervous system. This is the system responsible for
“fight or flight” and other similar behaviors. For this reason scientists call
methamphetamines, cocaine, and other central stimulants sympathomimetics, meaning they act upon the sympathetic nervous
system.
Chemical Characteristics of Methamphetamines
Chemical messengers, or neurotransmitters, communicate
information at specific receptor sites. Methamphetamine is a compound that
mimics a neurotransmitter at serotonin
(5-HT) and dopamine (DA)
receptor sites, which means that it relays information as though it were that
specific neurotransmitter. The
relationship between receptor and receptor site is similar to that of a lock
and its key; the receptor site (lock) is prepared to receive only information
that the specific neurotransmitter (key) recognizes as its chemical
counterpart.
Methamphetamine increases the release and blocks the uptake of
dopamine. These monoamines, along with norepinephrine, (NE), and
epinephrine (E), play a critical role in understanding the way in which
methamphetamines act upon neurotransmitters in the sympathetic nervous system
and act on the behavior of the organism.
Behavioral Effects of Methamphetamine
The dopamine and serotonin
systems influence aggressive, defensive, social and sexual behaviors. Users of methamphetamines exhibit
exaggerations in these behaviors.
Bipolar (manic-depressive) people might also behave this way. People using speed also exhibit behaviors
similar to a schizophrenic.
In animal studies,
methamphetamine consumption stimulates locomotor activity, and produces stereotypic behaviors. These have been related to the
norepinephrine, dopamine and serotonin systems.
Drug-related stereotypy is term referring to repetitive behaviors. In rats, stereotypic behaviors may include
head sways, hyperactivity, avoidance behaviors, and automutilation (self-mutilation).
E.Rylander, a researcher in the 1960’s, studied several Danish
methamphetamine users. He was the first
to note a behavior known as Punding. Punding is performing a useless task
compulsively again and again. This
seems to be the human equivalent of drug-related stereotypy.
Interestingly, these Danish
users reported being aware of their Punding behavior, but were unable to cease
performing it. The behavior could be
assembling, disassembling, and reassembling an apparatus after a compulsive
fashion. Punding is known colloquially
as “tweaker habits,” and could
include coloring, writing, playing cards, or taking apart items in a prolonged
and bizarre manner.
Amphetamine psychosis is another prominent aspect of
methamphetamine use, and is nearly identical to full-blown schizophrenia. There is a direct relationship between this
psychosis and the alterations in the DA system. Other similarities include hallucinations, aggression, and
increased excitability.
Biology,
Behavior, and the Brain
Animal studies have cast a fascinating light into drug studies at
a cellular level. The basic assumption behind
all drug use is that it does not take place repeatedly in the absence of some
kind of reinforcement or
reward. One contemporary model used as
a framework for the biological basis of addiction is called the "Brain Reward System.” This model studies the psychological and
chemical aspects of drug addiction, proposing that an organism engages in a
drug-seeking behavior because it is somehow rewarding for them to do so. Experiments show that an animal will work to
obtain electrical stimulation to the lateral
hypothalamic brain region. Drugs
such as methamphetamine lower the threshold for this rewarding brain
stimulation.
For psychologists, these are
important activities to investigate, because it is essential to understand what
the "hook" is for people who get "hooked." (The trouble with drugs is that people who
use 'em just keep on using!) The answer
to the question, "WHY "is a bit involved, however.
Biopsychology
and Addiction
Biopsychology is the study of behavior from a biological perspective. Researchers have established that central
stimulants, including methamphetamine, have very specific actions on certain
brain structures. These structures,
including the brain's pleasure centers, are stimulated, which creates a pleasurable
effect on the organism. Studies also
show that when an animal receives a stimulant, its reward threshold (minimum level at which an organism becomes
sensitive to a pleasurable stimulus) is reduced, an immediate response to a
small amount of drug. This
electrochemical stimulation is what produces sensations of euphoria.
The sensation of euphoria
encourages the organism to repeat the pleasure-producing behavior, but a tricky
thing happens after the user experiences the initial enjoyment: It quits being
as enjoyable. The reward threshold
increases again, meaning that while these drugs may be pleasurable at first,
the sensitivity to the drug quickly goes down, and the drug fails to yield the
same euphoric results.
This phenomenon is
called "Chasing the Ghost" by drug users. There could be an internal mechanism that serves to protect the
system from toxification
(poisoning), yet the insanity of addiction drives the creature to pursue the
pleasurable sensation again and again.
The destructive action of
this drug is compelling and profound.
Though it is unlikely that drugs will affect every being identically,
this overview of the biopsychology of methamphetamine use paints a dark image
for anyone who considers using meth.
One might wonder how an
understanding of neurotransmitters and Brain Reward Systems can have any impact
on the monstrous problem of drug addiction.
Some argue that it is a problem only experienced by people of weak moral
constitutions or defective characters. In reality, methamphetamine abuse and
addiction is an affliction of many people in many cultures. "Fathers, soldiers, sons," anyone
can join the ranks of methamphetamine addicts.
It remains a leveling influence, a great "respecter of no
one."