Born This Way? Genetics and Drug Abuse


There’s an old argument in the addiction field about “nature vs. nurture.” The key questions are whether we are genetically determined to become addicts or whether free will and our circumstances are the most important factors.

An Old Picture Revised

The traditional picture of addiction, and one that is still largely taught in AA, is behavior comes from a moral, or spiritual choice. Alcoholics Anonymous literature is replete with the idea of addiction as a character flaw or a spiritual disease. It once seemed obvious that people chose addiction in the way they might choose any other evil act.

As addiction specialists learned more about the psychology and biological drivers for addiction, this picture began to change. Studies were done that matched up alcoholics and other addicts to their cultural backgrounds and early family situations. Epidemiologists were able to estimate increased risk for those raised by alcoholic parents (one or both) and separate out how much could be blamed on nurture over nature.

In parallel, biologists were exploring the roots of behavior, including mental illnesses and addiction, from the “nature” side. The questions are related: Why does one person become a schizophrenic and another avoid the disease? What’s the risk of depression if your parents are depressives? Researchers were able to find genetic differences that helped explain why one person could tangle with drugs and not become an addict, and why another couldn’t. But it wasn’t a complete answer.

The new picture doesn’t answer “nature or nurture” so much as it says both are important elements which interact with each other.

Looking at the extremes should make this plain. Someone who has no access to any addictive substance will not become addicted – pretty simple. On the other hand, someone who is forced to use (for example) a narcotic, as with long term pain relief, will definitely become physically addicted to the drug. In the real world, there’s a mix of exposure to addictive substances and a propensity to adopt the addiction behaviors, no matter what genes someone is born with.

The description that emerges is one where addiction is a disease that is influenced, but not completely, by genetic differences.

Is There an Escape?

A recent estimate from the American Psychological Association puts the genetic influence at about 50%. They refer to it as genetic susceptibility and assume the number is actually much higher. It’s probably higher because we are still discovering new ways that genes alter how we react to drugs of abuse. Whenever a new link is found, that pushes up the number of influences genes are known to have.

A 2005 paper in Neurobiology of Addiction (downloadable pdf file) lists 28 different genetic variants linked directly to different drugs. More have been discovered since.

One critical finding, however, is that genetics isn’t the same as destiny. No one is forced to become an addict because of their genes, in the same way that no one is forced to become a type II diabetic even though they are at risk. In that latter case, diet and exercise play a huge role, while for addicts, exposure and drug seeking come into the mix.

Can we escape our genes? In the case of addiction, the clear answer is yes. We know this because we have innumerable examples of people quitting and we can find (through genetic testing) those who never started in the first place. Remember, it’s not genes alone, but genes coupled with environment. If you have a genetic predisposition to become an alcoholic, but avoid alcohol, nothing happens. The cards are never played.

What It All Means

There are several important messages here. The first is that an addict has a disease, not a moral failing. Often, because addicts tend to become immoral in the service of their addiction (quite often committing crimes, for example) these two things get mixed up. We mistake what someone has become, because of their addiction, with an insurmountable character flaw.

The second important thing is that these genes do not simply code for becoming addicted to a particular drug (although some do alter drug responses). That’s too simple. What seems to be the case is that the complex behavior of addiction is driven by things like impulse control, risk taking behavior and the way we respond to stress. Comorbidity – a second condition that comes alongside an addiction – is also quiet common. For example, it’s hard to tell if someone turned to drugs to fight depression or became depressed as part of the addiction cycle. An addiction is just part of the totality of the patient, and humans are very complex creatures.

Genetic differences really do change the response to a drug. This is known for many drugs, not just those that cause addiction. These different responses can be treated with pharmaceuticals. However, addiction will remain – remember, there are those that become addicts without any genetic predisposition at all. We can’t expect to find a magical “cure.” We also can’t expect to be able to screen kids and figure out much more than that they are at a higher risk – you can’t predict, based on genetics, who will become an addict and who will not.

The final message is a positive one. No one is trapped by their genes in addiction. Behaviors can change. We can overcome. Just as no one is born an addict, no one has to remain an addict for the rest of their lives. That’s good news.


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