There are many different kinds of addictions, from drugs to interpersonal
relationships. Although these diverse addictions vary in many ways there are
common threads that bind them together. There are several theories that model
addiction: genetic theories, exposure theories (both biological and
conditioning), and adaptation theories. To be successful, an addiction model
must blend the multidimensional aspects of addiction. It must account for
regional and cultural variation, interpersonal preferences as well as hold true
for the variety of addictions. In addition, a good model will describe a cycle
that exists that encourages increasing use until the addiction is overwhelming
and leaves the host lame. Lastly, theories must be able to describe addiction
as it occurs through human experience. Although animal studies can aid in
understanding behavior, results need to be carefully interpreted before they are
applied to the much more complex nature of a human being.
Genetic Theory
The genetic theory of addiction, known as addictive inheritance, attempts to
separate the genetic and environmental factors of addictive behavior. Studies
have been done to control for environmental components to determine if genetics
plays a greater role. Most studies looking at alcoholism have determined that
children born from alcoholic parents who are adopted into non-alcoholic families
have a three to four fold increase in the rate of alcoholism over the rest of
the population. Indeed, children born and raised by alcoholic parents have an
even greater rate of alcoholism. This suggests that there is some genetic
predisposition to alcoholic addiction.
Though a genetic component seems likely, exactly what the gene codes for has not
been elucidated. Questions arise as to whether or not it is the addictive
behavior that is encoded or a biological mechanism that drives the behavior.
Are there differences in the metabolism of various addictive substances that
allow an individual to have varying levels of a drug in the blood stream and
have a psychological experience different someone else? Is there some genetic
difference that perhaps allows some to realize when an elevated blood alcohol
level has been reached and transmits a message to the brain to stop drinking
that others do not have? These questions have not been clearly answered and are
under persistent investigation.
One aspect of inheritance that is understood is that amongst members
ofparticular races. Eskimos, American Indians, and Asians, for example, are all
genetically predisposed to have a deficiency in the production of acetaldehyde,
an enzyme important foralcohol degradation. Genetically similar in this regard,
these groups are hypersensitive to the affects of alcohol. They respond
immediately and intensely to the alcohol in their system. A characteristic
flushing, known as Asian flushing, ensues once higher levels of alcohol are
reached. Although this metabolic process is similar in all of these races, the
addictive behavior is quite different. Eskimos and American Indians have a
higher rate of alcoholism than Asians and are also predisposed for other
addictive behaviors such as gambling that is not seen in Asians. This has
raised the question as to whether or not a single gene can encode for multiple
addictive behaviors, or if the maintenance of one addictive behavior allows for
other addictions to arise more easily.
Finally, the strongest correlation between addiction and genetics comes when
evaluating the pattern of inheritance. All studies show that it is sons, not
daughters, who most often inherit the risk of alcoholism. How much of this
phenomenon has its basis in genetic is not clear. Could it be that sons model
themselves more after their fathers? Or is there a sex-linked genetic mechanism
at play that is contributing to this phenomenon? As research continues, the
role that genetics plays in addiction will be better understood. As of yet, it
is sure to be a major component of most addictions and at the very least will
predispose individuals to indulge in addictive behavior.
Exposure Theories: Biological Models
The exposure model is based on the assumption that the introduction of a
substance into the body on a regular basis will inevitably lead to addiction.
The biological, as opposed to the conditioning models, believe that this is a
consequence of biology. Underlying the exposure model is the assumption that
the introduction of a narcotic into the body causes metabolic adjustments
requiring continued and increasing dosages of the drug in order to avoid
withdrawal. Although changes in cell metabolism have been demonstrated, as of
yet they have not been linked with addiction. Some theorize that those drugs
that mimic endorphins (naturally occurring pain killers), if used on a regular
basis, will reduce the body's natural endorphin production and bring about a
reliance on the external chemical agent for ordinary pain relief.
