What Causes Substance Use Disorders? A Look at Physiological Factors

 In previous blogs, I’ve defined Substance Use Disorders (SUD’s) and addiction. In this blog, we‘ll begin to explore the factors leading to SUD’s. Our most current understanding of SUD’s is that they develop from a variety of factors often with one or more factors being predominant. The factors commonly fall into 4 primary categories: physiological, psychological, social/environmental, and spiritual. In today’s blog, I‘ll primarily focus on the first category; physiological factors.

We‘ve developed an understanding that, for some individuals and families, SUD’s seems to be more common in some families than in others. Is it because substance abuse is learned within a family system or is it because something genetic is inherited? A few important studies seemed to suggest the latter. In one study, children adopted out of an addicted family system early in life and raised by non-substance abusing families still had higher rates of SUD’s compared to children who were born to non-abusing parents. In another important study, identical twins of the same genetic make-up were compared to fraternal twins who were born at the same time, but who did not share identical genetic material. This study attempted to remove differences often associated with learned behavior within a family system. The study reported that identical twins had higher rates of substance abuse as they matured than their fraternal twin counterparts providing more evidence of genetic traits being passed on from generation to generation.

The studies mentioned above seem to suggest that, for some individuals, something is being inherited or passed on genetically, that makes some more vulnerable to addiction than others. But, what is it that is inherited remains elusive. Scientists have not been able to simply locate a specific gene which leads to a susceptibility to addiction. This genetic susceptibility seems to involve an interplay of several genes. Individuals with this genetic vulnerability also seem to share other common psychological disorders such as antisocial personality and attention-deficit hyperactivity.

One of the most intriguing questions in treating SUD’s is why aren’t we all abusing the same substance or substances? In other words, why do some individuals abuse alcohol, while yet others prefer cocaine, or marijuana, or heroin, or any other particular substance? Why are there individual preferences for mood-altering chemicals? The answer to this may lead to our understanding of what is being genetically inherited. A theory as to what is being inherited is often termed the “Self-Medication Hypothesis”.

The Self-Medication Hypothesis suggests that some of us choose particular, mood-altering substances because they compensate for deficiencies in chemicals that are naturally found in our brains. For example, dopamine is a naturally occurring chemical in our brains that give us the feeling of pleasure when released. Dopamine is released when we have sex, eat a nice meal, gamble, exercise or get high. We also know that cocaine, for instance, releases very high levels of dopamine in the brain. The theory suggests that when a person with abnormally low levels of naturally activated dopamine uses a substance such as cocaine, that person will have a greater activation of dopamine than they have experienced before. This may actually make the person feel more “normal” than ever before setting up a pattern of continued use and possible abuse of cocaine. Other chemicals in the brain handle other psychological states. For instance the neurochemical, GABA , when released, is associated with decreases in anxiety; serotonin is associated with mood; endorphins are associated with managing pain (emotional as well as physical pain). Different drugs of abuse work on different neurochemicals. Thus, the Self-Medication Hypothesis suggests that we seek out specific drugs of abuse in order to compensate for deficiencies in naturally produced neurochemicals.

Why is the Self-Medication Hypothesis only a hypothesis? The answer is because our current technology is not yet sophisticated enough to accurately measure levels of neurochemicals in our naturally occurring brains. We cannot yet determine, for instance, how much dopamine is currently produced in our brains and what the normal levels should be. Our ability to accurately measure these neurochemicals has not yet occurred although significant progress is being made. It is believed that, one day in the near future, we’ll be able to measure these neurochemical levels , thus allowing for accurate forecasts as to who is likely to develop addictive potential for different drugs of abuse. One day, we may even be able to alter neurochemical deficiencies and significantly decrease the likelihood of SUD’s for many individuals and families. What are your thoughts and reactions to this blog? Let us know.

Nicholas Lessa is the Clinical Director of Chat2Recovery, an online substance abuse treatment program, and Inter-Care, a leading substance abuse treatment program in New York City. He has been in the field of substance abuse treatment for over 30 years. He is the lead author of two books, Wiley’s Concise Guide to Mental Health: Substance Use Disorders and Living with Alcoholism and Drug Addiction.

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