by Alice G. Walton, Contributor
FORBESWOMAN | 2/06/2012
Addiction is one of the most common mental health problems there is: Drug use alone affects tens of millions of Americans, and that’s only the illegal ones. Even more people deal with addictions to other things – alcohol, caffeine, nicotine, food, and various behaviors. People who are familiar with addiction, and certainly the researchers who study it, may wonder whether their brains are fundamentally different from non-addicts, making them more prone to addiction’s grasp. Now, a new study offers an interesting answer to this very basic question.
The problem with studying behaviors (and also what makes them so cool) is that there are both psychological and biological components to them. After all, you can’t have a behavior without some cellular activity to go along with it. But even mapping out the biology behind behaviors doesn’t explain everything, since there’s always the lingering question of which came first, the chick or the egg: or here, whether differences in the brain lead to a given behavior, or whether it’s the other way around.
Researchers at Cambridge setup a wonderfully simple study to address some of these issues. We know that there’s a strong family component to addiction – but it’s not been clear whether it’s the brain changes that are handed down through the generations or the family environment in which one grows up that’s conducive to developing addictions (the old nature/nurture question). It’s also known that people who are addicts seem to have deficits in self-control, which is even seen in differences in certain areas of the brain that govern it. But whether it’s brain changes that are actually handed down from parent to child, and make some families more prone to addiction, had yet to be shown.
To figure out the answer to this question, the researchers studied pairs of siblings, one of whom was a drug addict and the other of whom was not. The pairs took a “stop-signal test,” in which one has to stop a particular action whenever one gets a cue to do so. Earlier studies have shown that because the test challenges your self-control – or your capacity to inhibit your own behavior – the test correlates well with addiction risk. Unrelated pairs of people did the same task, serving as controls.
The siblings – regardless of whether they were addicts or non-addicts – took significantly longer to halt their behavior than the control group. This could suggest that self-control runs in families, and the level of self-control between siblings is similar, regardless of whether they are addicts or not (more on this in a sec).
But do these behavioral differences correspond to brain changes? They seem to. Another part of the study looked at some of the brain’s white matter tracks, which serve as the lines of communication between brain cells in different areas. In the sibling pairs, there were deficiencies in the tracks that connected the emotion areas of the brain to the ones that govern self-control. So in other words, both addicted and non-addicted siblings had deficits in the connections involved in telling one to stop the behavior that one is engaged in.
The sibling pairs also had enlargements in the gray matter (brain cells) in regions that are known to be involved in addiction. All of these changes, in white and gray matter, could have “predisposed” the [siblings] to drug-taking,” the researchers conclude.
If you find this depressing because you have a relative who’s an addict (or come from a long line of addicts), don’t despair. Remember, one of each pair did not take drugs. Even with their “predisposed” brains, one sibling did not succumb to their brain morphology and become drug-addicted. It’s not totally clear why, but among the many reasons, it could have to do with minor differences in upbringing, and/or other variations in the brains of the un-addicted siblings, like some yet undiscovered “resilience factors that counteract the familial vulnerability.” Put another way, there are probably things going on in the unaddicted siblings’ brains/personalities that could help protect them and explain why they didn’t “succumb” to addiction.
The research also has implications for other disorders, like ADHD and OCD, in which people have problems in regulating their behavior. In fact the authors say that “like addiction, OCD is characterized by dysfunctional habits and ‘out-of-control’ behavior.” And in ADHD, people cannot ignore the stimuli that they should, which could be due in part to a faulty control center in the brain. Drug addiction involves a similar (albeit perhaps more severe) lapse in control: “Pathological habits in drug addiction typically result in compulsive drug-taking behaviors when prefrontal control fails to regulate behavior,” the authors say.
More research will be needed to understand how drug addiction is passed on, but the new study gives some nice clues into how “predisposition” may be transmitted. Just remember, your brain may be set up to lean in one direction, but you don’t have to follow it.