It’s the closest thing to fortune telling science has to offer — only in this case, it’s not your palms or horoscope being read, it’s your genes. Genetic testing for addiction identifies certain genes and their variations that may predict who’s at greatest risk of developing substance use disorders. And in a heroin and opiate epidemic that’s claiming 78 lives each day, genetic tests for opiate addiction are beginning to surface in clinics around the country. A quick and painless swab on the inside of the mouth that’s sent to the lab for analysis reportedly can tell doctors how a patient will respond to various opioid and non-opioid pain medications, including what their risks of dependency are.
A similar test that has been around longer can allegedly weed out individuals with elevated risk of alcoholism by measuring levels of the pleasure neurotransmitter dopamine. (Low levels of dopamine seem to indicate a higher propensity for alcohol abuse.)
More recently, researchers at the University of Indiana said they can now determine genetic susceptibility to alcohol abuse with still greater accuracy, based on a panel of 11 genes. (Some of the same genes have been implicated in the development of cocaine use disorder and other mental illnesses, such as anxiety disorders, schizophrenia and bipolar disorder.)
Just how valuable is current genetic testing for preventing and treating substance use disorders? Here are five things to know that help answer this question:
Genetic testing is still very much an imprecise science. DNA sequencing technologies have unveiled a number of “addiction genes” — so termed because they are related to a person’s vulnerability (or lack thereof) to substance abuse. Among these many discoveries, it is now known that the A1 allele of the dopamine receptor gene “DRD2” occurs more often in people with alcohol or cocaine addiction. Scientists also know that mice mutated with a defective “Per2” gene drink three times more alcohol than mice without the mutation. And, strikingly, non-smokers are more likely than smokers to carry a particular gene combination that seems to protect them from nicotine addiction.
Such discoveries testify to how far addiction science has come, but their scope and accuracy of prediction remain limited, nonetheless. Take, for example, the University of Indiana study mentioned earlier. There the researchers reportedly conceded that while their results were very effective as a statistical probability tool (for assessing risks of alcohol abuse across a population), people looking for a precise evaluation of their own predisposition for alcoholism would have to look elsewhere.
Just how accurate were the results of the study for predicting alcohol problems? About as accurate as flipping a coin, according to one Emory epidemiologist, in a blistering critique published in The Huffington Post.
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Genetic testing is only one piece of a very complex puzzle in resolving the problem of addiction. Genetics are an important predictor of substance abuse, but they are by no means the only one. Genes may account for anywhere from 40 to 60 percent of an individual’s predisposition to drug or alcohol problems. That leaves open a very big gray area for a host of other variables in the form of environmental risk factors — and these run the gamut, from family of origin to incidence of stressful events to lifestyle choices like diet and exercise. Complicating matters even more, the latest insights from epigenetics have established that both these risk factors (not just environmental influences but genes themselves) change and evolve across a lifetime.
Genetic testing is no magic bullet for catching or preventing addiction before it develops. Even if its results were 100 percent accurate in gauging people’s predisposition for addiction, existing research suggests genetic testing would do very little to encourage healthier lifestyle choices on the part of those at risk. In fact, in some cases genetic testing may actually discourage healthy thoughts and behaviors that protect against addiction, according to researchers from the University of Sydney. They reportedly found that when test subjects were told they had a gene for alcoholism, they became less emotionally positive and were more likely to assume they had less control over their drinking. (Negative, fatalistic thoughts in relation to managing drinking behaviors are a common feature of SUDs.)
[See: 7 Health Risks of Binge Drinking You Can’t Ignore.]
Genetic testing can better inform treatment decisions. The “Proove Opioid Risk” test, which combines a DNA swab test with a six-question clinical assessment, is a good example. The questions are pretty basic: For instance, patients are asked if they have a diagnosis of depression or a past history of substance abuse. Their DNA sample is then analyzed for 12 different gene variants in the brain’s mesolimbic or reward pathway. An algorithm processes the results, providing doctors with a “low risk,” “moderate risk” or “high risk” assessment of their patient’s addiction profile. If the results are even roughly accurate — the manufacturer apparently claims a 93 percent success rate at predicting a patient’s predisposition for addiction — they can help doctors do a better job of personalizing and monitoring treatment plans for individual patients.
Genetic tests should not take the place of a comprehensive clinical assessment with an addiction professional. For as much as is now known regarding the genetic underpinnings of addiction and the genes that may predict it, we’ve only scratched the surface. Only five years ago, in an article on the state of addiction genetics, researchers noted that, “more than 95 percent of the genetic variance remains unaccounted for, indicating that most of the genetic risk factors for addiction have not been discovered yet.”
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To be sure, it would be safe to assume that advances in the last five years have made a dent in that 95 percent. Still, far more work remains to be done in solving the full mystery behind why some people get hooked to drugs and alcohol and why others do not.
This reality invites some caution about the utility and validity of take-home genetic tests for addiction. However old-fashioned it may one day become, a comprehensive clinical assessment with an addiction professional is still the most effective route to gauging one’s risks of substance abuse and getting the right medical advice.
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Genetic Testing for Addiction: 5 Things to Know originally appeared on usnews.com
