The basis for addiction

Scientists have long accepted that there is a biological basis for drug addiction, though the exact mechanisms responsible are only now being identified. It is believed that addictive substances create dependence in the user by changing the brain's reward functions, located in the mesolimbic dopamine system—the part of the brain that reinforces certain behaviors such as eating, sexual intercourse, exercise, and social interaction. Addictive substances, through various means and to different degrees, cause the synapses of this system to flood with excessive amounts of dopamine, creating a brief rush of euphoria more commonly called a "high".

Although the high may last only a few minutes, it also produces more longer-lasting effects in the brain. Dopamine signals occurring normally in the reward system (traveling from the ventral tegmental area to the nucleus accumbens) lead to the activation of proteins designed to calm the initial reaction and foster a continued desire to pursue the behavior responsible. Addictive substances create a greater than normal dopamine release, and the subsequent reactions of the brain are greatly exaggerated as well. The amygdala, hippocampus, and frontal cortex associate the use of the drug with intense pleasure and well-being; an association that is strengthened with each exposure, and which over time comes to dominate normal thoughts and desires. When cravings for the drug are no longer controllable, the user is considered addicted. (For a contrary view of drug addiction, see Rat Park.)'

Some in the medical field believe that what we call addiction is self medication for PTSD. In addition Dr. Lonny Shavelson, in his book "Hooked," has reported that 70% of female heroin addicts were sexually abused as children. There also seems to be a genetic component to addiction. It is a little researched but well known secret in practicing medical circles that many addicts are self medicating for what we commonly call anxiety problems. PTSD is thought to be a common cause as is ADD/ADHD, and bipolar disorder. Some research is being done on the subject, more needs to be done.

Evolutionary psychology view of addiction

It is obvious that genes for addiction would not be directly selected. Since evolution theory claims that every physical and behavioral trait is a direct or side effect of selection, then the capacity to be addicted to drugs must be a side effect of something that was selected.

A number of writers including Keith Henson [1] have suggested that the capacity to be addicted to drugs is a side effect of social attention rewards. It is easy to understand how sensitivity to social rewards would evolve in social primates. For example, Jane Goodall's observation that chimpanzees who hunt get additional mating opportunities. The proposed evolved mechanism for social rewards is that attention causes the release of endorphins and dopamine into the brain's reward circuits.

It is proposed that addictive drugs activate brain reward circuits that are normally activated by attention, without the need to kill a large, dangerous animal and drag it back to camp (or modern equivalents.)

 

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