Why are some behaviors so incredibly difficult to change? This is a mystery to all of us--to the general public, to patients, and to professionals including physicians and therapists and educators. And, but I’ll come to this later, it’s a mystery to neuroscientists as well.
I can think of three examples:
Depression and anxiety disorders are not always easy to treat, but once they do respond, whether to therapy, medication or other approaches, it’s not unusual for symptoms to nearly disappear. In stark contrast, symptoms of OCD and anorexia often only partly resolve--even with extensive treatment. And drug abuse can be difficult to keep in remission: even after years of sobriety, full-blown drinking or drug use can be easily induced by environmental cues--the proverbial ‘people, places and things’ that remind former users of their days of active intoxication, and can trigger complex sequences of drug-seeking behaviors.
Why is that?
In the past few years, neuroscientists have come up with a compelling explanation. In brief, that these disorders result at least in part from what is called ‘habit learning.’ Habit learning is incredibly valuable, since it relieves our minds of the burden of consciously working throughout routine daily activities. It protects us: for instance, while driving a car, we rely on habit learning to keep us safe in a constantly-changing environment, and don’t really have to ‘think’ every time we put on the brakes or change lanes. We can even have a conversation or listen to the radio without endangering our lives. Obviously, innumerable habits of this sort and others make our lives possible.
Habit learning theory brings together these and other seemingly unrelated conditions.
According to the habit learning theory, anorexia nervosa, OCD, and drug abuse all involve sequences of thought and behavior that were initially easily controllable. At first, they were based on ‘reward dependent learning’: at the beginning, it felt good for a young woman to diet, for instance. Checking the lock on his front door several times relieved a man’s worries. And having a few drinks made you feel better after a long day of work.
But over time, these behaviors become habitual: they have, in a sense, gone far beyond the immediate benefits that they evoked. Weight loss begins to become a goal in itself. Checking relieves anxiety, but only momentarily, and needs to be repeated many times just to ward away further anxiety. Drinking no longer feels good, but not drinking feels worse. As such habits develop and strengthen, the external world slips away.
Once they are locked into habit circuitry, such behaviors tend to be repeated month after month, year after year, regardless of environmental consequences, and regardless of whether they are still rewarding or not. And, most frustratingly, such habits may continue for months and years, regardless of whether we want to continue those behaviors.
Take eating, for example. Obviously, our society’s obsession with appearance and weight control compels all of us--but particularly young women--to focus on certain behaviors. We all watch our diets these days, we all try to get regular exercise, and no doubt, many of us stand in front of the mirror each morning or night, wishing that what we saw there better matched our society’s ideal body types. And so, we tend to avoid fattening foods, or carbs or gluten or whatever we believe to be unhealthy; we try to go to the gym regularly; and we develop the habit of practicing a level of self-denial for reasons of health or appearance or both.
If we’re lucky, the habits we develop will be ‘good habits’--or at least, not overtly harmful. Our sequences of thoughts and behaviors related to health will become ‘habitualized’ so to speak, past the point of immediate rewards, so we will be able to fend off the cheesecake at a fancy restaurant, and to push ourselves to go jogging even though the weather is gloomy today.
But for some of us, the unlucky ones, our habits will go too far, will escape from us. They will become our masters, despite what we might want.
Reward-dependent learning and habit learning, as neuroscientists have shown, involve different brain circuits. Whereas reward-dependent learning tends to involve the front parts of the brain, the cortex and the temporal lobe and the hippocampus, habit learning tends to involve the lower parts of the brain, including the striatum and basal ganglia.
But why do some habits veer out of control?
This is the part that none of us, psychiatrists or therapists or neuroscientists, have yet figured out. At best, we are only beginning to have an idea of why some people are more vulnerable to disorders of habit learning, why for some young women a focus on appearance and diet becomes just a part of life, and for others it ruins their life. Or why one person will be able to control his anxiety or his drug use without succumbing to dangerous behaviors. And that has to do with anxiety. In states of high stress, the brain naturally tends to favor habit learning circuits. This makes sense: if you’re stressed, it makes sense for your brain to react based on well-learned response patterns, whether if you are in a forest trying to escape a predator, or if you are driving on an icy highway: in states of crisis there’s often no time to think things through. Further, people who are high in anxiety may have a tendency to favor the creation of habit learning circuits; and it’s clear to therapists that patients with anorexia generally suffer from high levels of anxiety even prior to their development of eating disorders. Another contribution is a tendency toward rigid thinking, a certain level of obsessiveness and need for order: this clearly exists in many people who develop anorexia. On the other hand, people who develop substance use disorders tend to have more impulsive behaviors, so for them habit learning may take a different course than in AN.
Understanding the importance of habit learning in the development and maintenance of these wide-ranging disorders may lead to key advances in treatments, whether medications or therapy or even brain stimulation which can now potentially target those circuits. One thing has become apparent: since habit learning circuits are so hard to erase, it’s often best to focus treatment on creating NEW habits—developing and then strengthening new and more adaptive behavioral circuits that can provide alternatives to the maladaptive ones. For instance, Alcoholics Anonymous for substance abusers. And cognitive behavioral therapy for OCD: both are effective, by creating new sequences of behavior and habit.
But these advances in understanding habit learning also raise a new series of mysteries: why are some of us so vulnerable to develop aberrant habit learning behaviors -- while most of us are able to interrupt these cycles before they get locked into place?
After all, many of us went through periods of heavy substance use in college without developing substance dependence. Many of us have had periods of time when we had some level of checking or counting behaviors, without developing OCD. And many young women have periods of subclinical eating abnormalities, especially in college years--compulsive exercise and diet--without developing anorexia nervosa. Among those who do develop anorexia, about half have a complete recovery--their habit of self-starvation fades away.
Which is where the mystery remains...opening the door to new studies that may have a chance of improving treatment for these disorders.
Why are some of so vulnerable to develop sticky habit circuits? And why are others protected? These are mysteries that neuroscientists are just beginning to explore. Once they understand that better, then we will be able to ask further questions: how can clinicians identify those individuals who are vulnerable, and design interventions that can help them interrupt the cycles of aberrant habit learning early--before they get locked into place?
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