Advantages and Limitations of the Genetic Model

Although the research on genetic factors that predispose one to developing substance use disorders is very convincing, as indicated earlier, there is rarely, if ever, a 100% concordance rate (or likelihood) that one will develop an SUD, even if both parents are diagnosed with severe SUDs. Think of it this way: it is unlikely that you will inherit all of your parents’ traits or characteristics.This point was raised by Gabor Maté in his bestseller, In the realm of hungry ghosts (2010). He hypothesizes that addictions are rooted in trauma from our past, emotional pain, failure to connect in meaningful ways with others, and societal values which overemphasize consumerism and external goods as a way to soothe one’s distress or misery. Maté points out that workaholism and addiction to shopping are at their all-time high and represent an attempt to feel good by acquiring tangible objects rather than seeking solace or peace in our connections with loved ones. Maté (2010, p. 38) exclaims:

Not all addictions are rooted in abuse and trauma, but I do believe they can all be traced to painful experience. A hurt is at the center of all addictive behaviors. It is present in the gambler, the Internet addict, the compulsive shopper, and the workaholic.The wound may not be as deep and the ache not as excruciating, and it may even be entirely hidden — but it’s there.

The other limitation of the genetic model surrounds the uncertainty of what exactly gets inherited that predisposes one to become addicted. Although the aforementioned research performed on sons of alcoholics is also convincing in explaining what appear to be essential differences between sons of alcoholics compared to sons of non-alcoholics, it has yet to be determined what exactly gets inherited that predisposes individuals to develop SUDs.

It is important to take note that in trying to answer the question “How exactly do SUDs get genetically transmitted?” there has been another body of research that was developed by Dr. Ernest Noble at UCLA’s Neuropsychiatric Institute and Dr. Kenneth Blum and Dr. Peter Sheridan from the University of Texas (Blum et al., 1990) which attempted to identify the actual gene variations (or anomalies) that might explain why certain biological offspring (e.g. identical twins) were at high risk for alcohol use disorders. It is estimated that thereare approximately 3,000 human genetic diseases which get passed down from one generation to the next generation. These genetic diseases are caused by defects in the DNA (the substance in the chromosomes that carries the genetic code for the production of genes; Blum & Payne, 1991). This search for an “alcogene(s)” has yielded some interesting findings. According to Blum and Payne (1991) “each cell contains a billion pairs of DNA which are stored in 46 packages called chromosomes. These chromosomes act in pairs, so there are 23 pairs in each cell. At conception, half of the chromosomes of each pair are derived from the egg of the mother and half from the sperm of the father. Each chromosome is made up of many genes ...” (1991, p. 227. Without getting into the rather complex details of the experimental research, what Noble, Blum and their colleagues thought they discovered was the specific gene variation which results in alcoholism. They hypothesized that the Al allele gene transmitted an unusual pattern (possibly a genetic defect) in the dopamine D2 receptor gene. This research was very promising in that it seemed to locate both the specific gene variation that causes alcoholism and how it does so (i.e. by causing disruptions in dopamine production; dopamine is one of our “feel-good” neurotransmitters that gets released when we ingest alcohol or drugs). Unfortunately, attempts to replicate these findings had failed; there have since been other attempts to find specific gene variations that are predictive of alcohol use disorders in the offspring of alcoholic parents, however (see McGue & Irons, 2013). However, Dr. Judith Grisel (2019) author of Never enough:The neuroscience and experience of addiction concludes that the years of research in trying to find specific gene variations that would put to rest, once and for all, the claim that substance use disorders are genetic in origin has not conclusively found the “smoking gun” of gene variations or genetic sequences that are present in alcoholics but not present in social drinkers or abstainers.

Learning Opportunity 5.3

If a specific gene were to be definitively identified that was thought to genetically transmit substance use disorders and let’s say you were considered to be at high risk for developing an SUD, would you be willing to be genetically tested using a DNA saliva test? If so, why or why not? Would you encourage your biological loved ones to be tested?

Grisel (2019) concludes that the research which sought to find specific alcogenes in DNA strands may have been too simplistic. She points out that more cutting-edge research in the area of epigenetics may be more fruitful in determining the role of genetics in substance use disorder transmission from one generation to the next. Epigenetics (literally means “on top of genetics”) examines the role of RNA, which acts as messengers, which may “communicate” how DNA will express itself. In other words, it’s not simply that one inherits particular DNA gene variants but how those DNA variants become expressed, which is where KN A and epigenetics comes in.