stephan at ucla.edu
Mon Nov 9 04:08:30 EST 1998
In article <7226jv$884$1 at morgoth.sfu.ca>, cgoodin at sfu.ca (Charles
Frederick Goodin) wrote:
> I'd always heard that marijuana (or THC) wasn't physiologically
> addictive. Recently someone mentioned to me that there'd been some
> research that went against this. Has anyone heard anything?
The term "physiologically addictive" is meaningless. All behavior is
based in physiology and when people say "psychologically and not
biologically addictive" it just means they don't know what the neural
substrate is. Obviously drugs produce their effects on the brain through
physiological action (they are not your mother), and the term
"psychologically addictive" is not really relevant (don't get me wrong,
maybe you can be psychologically addicted to love, but not drugs).
Now, what people are usually refering to in "physiologically" addictive is
that the drug produces dependence. The definition of dependence is that
there is a marked withdrawal syndrome upon abstinence from the drug. By
this definition, THC is not addictive, because the abstinence syndrome is
mild or nonexistent.
However, dependence is a poor definition of addiction. In fact, lots of
things produce dependence that don't produce any real addiction (a good
example is aspirin, which with repeated use will cause headaches in
withdrawal; similarly, nose drops produce a severe withdrawal syndrome).
Sure, dependene can motivate some behavior, but it's not like real
addiction. Plus, lots of drugs are highly addictive that produce very
little dependence (i.e., withdrawal). GOod examples of these are
amphetamine and cocaine, for which the abstinence syndrome is relatively
mild. Plus, the two drugs which produce the MOST DEPENDENCE, barbiturates
and alcohol (for which the withdrawal is life threatening) are very
CLEARLY not the most addictive.
So back to the original question, then there are two prominent definitions
of addiction. One is based on the negative reinforcement model where you
take drugs to avoid withdrawal. By this definition, the opiates,
barbiturates, and alcohol are the most highly addictive, and THC would
score low or not at all. By the second definition, which is based on
positive reinforcement, addiction reflects the positive hedonic effecs of
the drug (the drug rush) and conditioned effects which lead to compulsive
drug-seeking and taking behavior. By this definition, amphetamine,
cocaine, and heroine (but not morphine) are the most addictive. again, THC
would score low here. So for the average person, no THC is not addictive
by either definition of drug addiction. Plus, generally speaking,
animals will not self-administer THC; but they will under some conditions,
for example, if they are under anxiety.
Now here is where it gets complicated. Whereas most people do not show a
big rush from THC and do not show compulsive drug seeking or drug taking,
or dependence, some people actually do. There are well documented cases
(although rare) of marijuana addicts who take the drug several times a
day, and also cases of people exhibiting marked withdrawal symptoms. So
the long and short of it is, that some people may be addictable to
marijuana.... this is probably the case with every drug, as marked
individual differences are observed even with the most addictive drugs
(e.g., crack, crystal meth, and heroin). So you may become addicted,
although this is quite unlikely. And there are plenty of drugs approved
for medical use which have clearly higher abuse potential.
All this said, the other negative aspects of marijuana use should be
considered. First, smoked marijuana contains potent carcinogens which are
plain bad for your health. Second, it is illegal for recreational use and
you may prevent yourself from getting the job you want unwittingly... some
drug tests are quite sensitive to marijuana use for some time. Third, as
with any mind-altering drug, be careful the company you keep especially if
you are doing it for the first time, because, depending on the individual,
these drugs can have unpredictable effects in some people.
Stephan Anagnostaras, PhD
More information about the Neur-sci