The biological model of addiction’s basic premise is that addiction: is an illness; that it is irreversible; that you are either addicted or not (there are no slightly addicted individuals) and that treatment must be medical. There are many models of biological addiction mainly because current psychological research suggests that different areas of the brain are involved in different addictions (quashing the idea of an addictive personality per say).
In this essay two biochemical theories will be discussed, plus the genetic model. The latter theory should not be seen as distinct from the biochemical theories as biologists would propose that any biochemical abnormalities that may predispose an individual to addiction are probably inherited. Thus studies looking at concordance rates of addictions in families, twins and adopted children would support all three of the models being discussed.
One of the most popular theories of addiction is to do with the neurotransmitter Dopamine. Dopamine is involved with our pleasure/reward system. Anything we do of our volition that is pleasurable increases Dopamine. It is the release of dopamine that makes us feel Euphoria/pleasure. Drugs such as Cocaine, Alcohol and Heroin make Dopamine receptors release enormous amounts of Dopamine, so the user may feel intense pleasure. This however, does not explain addiction as many people drink or recreationally use cocaine and don’t become addicts. The main idea of the theory is that individuals biologically susceptible to addiction have more sensitive Mesolimbic/ reward pathways in their brain, e.g. drugs may have a more profound (wow factor) on their Dopamine receptors.
Another theory that may work alone or in conjunction with the Reward theory is that individuals with addictions may naturally produce low levels of Serotonin. Serotonin is thought to be a major factor in controlling our behaviour. So most of us can get drunk overeat etc but not repeat the behaviour compulsively. This is because our Serotonin levels are stable. It is thought that individuals with low levels may not be able to exercise control. There is support for this idea, e.g. low levels of serotonin are correlated with compulsive suicide, homicide, Bulimia and ADHD.
Another suggestion has been that there is a genetic basis for developing an addiction. Although a specific gene has not been found, there is plenty of research that shows high levels of concordance between families who are addicted to: alcohol (Sarafino), Nicotine (Agrawal and Lynskey, Heroin (Devaux and Krebs) and Fowler (see Erika Cox book). However like all correlational studies this kind of research cannot imply cause. The concordance could be caused by environmental factors or social learning. Additional support for the biochemical theories comes from MRI and PET scans, animal studies using agonists and antagonists and invasive brain techniques on animals, such as neuro toxins where Dopamine receptors are removed.