A new study by scientists at the University of Cambridge seems to shed new light on how compulsion disorders affect decision-making. Published this week in the journal Molecular Psychiatry, the study examined how the brains of 150 meth addicts, alcoholics, and compulsive eaters dealt with everyday choices, as compared with healthy subjects.
Prior to this research, studies have shown that we make decisions using one of two distinct processes. Some of our choices are based on our future goals, while others are made out of habit and our recollections of past benefits from similar decisions; scientists think these two processes occur in different parts of the brain.
In order to test this theory, subjects were put through a computer training program that gauged their ability to overcome habitual, compulsive impulses to act in a way that reflected future goals. The researchers compared the results of the training to MRI scans of the subjects' brains. They found that those who suffered from compulsive disorders tended to make more habitual decisions rather than prudent, goal-oriented ones, as compared to the healthy volunteers. Further, the scans showed that these subjects had fewer neurons in the orbital frontal cortex and left ventral striatum, which are known to handle our perception of goals and rewards.
This finding is the latest in a growing body of research suggesting that compulsive behavior — whether it's drinking, exercising, or eating — is due to factors outside of an individual's control. In this case, of course, the important factor seems to be an inherent inability to set goals or consider the future when making decisions. Study lead author Valerie Voon puts it this way: "Seemingly diverse choices — drug taking, eating [unhealthy food] despite weight gain, and compulsive cleaning or checking — have an underlying common thread: Rather than a person making a choice based on what they think will happen, their choice is automatic or habitual." Of course, it will probably take more than a few brain scans to change people's minds about compulsive eaters (and addicts in general). But, this study provides yet more proof that "self-control issue" doesn't even begin to cover it when it comes to disorders like these.