Final Common Pathway Theory of Addictions

From Medical Model to just looking at what happens...

There have been many challenges to the medical model of substance abuse, in that addiction is not entirely genetic. Additionally there have been challenges to the psychosocial models of drug use as being too narrow in scope and not being able to account for the specific phenomenon of addiction.

A different viewpoint to consider is called the Final Common Pathway (FCP) theory of chemical dependency. In a very real sense, FCP is a non-theory: It is not supported by any single group of profession. However, the final common pathway perspective holds that substance use/abuse is not the starting point but, rather, a common end point of a unique pattern of growth.

The FCP holds that: there is no single “cause” of drug dependency, but a multitude of different factors that may “cause” a given individual to become addicted. These might include social forces, psychological conditioning, an attempt on the part of the individual to come to terms with internal pain, a spiritual shortcoming, or some combination of other factors. The proponents of this position acknowledge a possible genetic predisposition towards substance abuse. But the FCP theory also suggests that people who lack this genetic predisposition to drug dependency may also become addicted to chemicals, if they have the proper life experiences.

Strong support for the final common pathway model of addiction might be found in the latest neurobiological research results. Over time evolution has equipped humans (and many other species) with a “reward system” that is activated when the individual engages in some activity that enhances survival. The drugs of abuse seem to activate this so-called “pleasure center” of the brain. In effect, the various drugs of abuse “create a signal in the brain that indicates, falsely, the arrival of a huge fitness benefit.”

An impressive body of research suggests that the nucleus accubens, an subunit of the region of the brain known as the basal ganglia, is part of the brain’s reward system. Virtually all drugs of abuse including nicotine (and methamphetamine) stimulate dopamine activity in the nucleus accubens. Other researchers believe that recreational drugs are able to cause the user to feel pleasure by altering the function of the mesolimbic dopamine system of the brain (emotional areas as well). This also seems to be the region of the brain most involved in the individual’s subjective experience of “cravings” for his or her drug of choice, when he or she stops using it, and in drug-seeking behavior.

The mesolimbic dopamine system seems to function as a focal point for the brain’s reward system, projecting electrochemical messages to the limbic system (where emotions are thought to be generated) and to the frontal cortex (a region of the brain involved with consciousness and planning).

Another area of the brain that drugs of abuse alter is the locus ceruleus. The locus ceruleus appears to be the region of the brain that coordinates the body’s response to both novel stimuli and internal stimuli that might signal a danger to the individual. Thus the locus ceruleus will respond to such internal stimuli as blood loss, hypoxia, and pain. The locus ceruleus region is also involved in the “fight or flight” response of fear and anxiety.

Although different researchers have suggested that different regions of the brain are involved in the addictive process, it is important to remember that they have all identified the mesolimbic system as being involved in the pleasure response induced by the various drugs of abuse.

The final common pathway model of addiction views alcohol addiction and drug addiction as common end points. There may be different routes, but eventually the chemical result is the same: activation of the brain’s “pleasure center.” Each different class of recreational chemicals might also affect other regions of the brain besides the pleasure center, but they all induce a state of pleasure by altering the function of at least part of the limbic system. This is not to say that the individual is just a helpless victim of his or her genetic vulnerability to the reinforcing properties of the drugs of abuse. Rather both a genetic predisposition and environmental factors interact to bring about a state of vulnerability to drug abuse. If either element were missing, the individual would be unlikely to become addicted to recreational chemicals.

In order to treat the addiction the chemical dependency counselor must identify the forces that brought about, and those that support, this individual’s addiction to chemicals. On the basis of this understanding the chemical dependency counselor might establish a treatment program that will help the individual abstain from further chemical abuse.

Excerpt taken from: Concepts of Chemical Dependency, 5^th Ed. Harold E. Doweiko

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