Bad habits get wired into our brains

That is not an excuse to give up. Understanding how unhealthy behaviors become ingrained has scientists learning some tricks that may help good habits replace the bad.

“Why are bad habits stronger?’’ said Dr. Nora Volkow, director of the National Institute on Drug Abuse. “You’re fighting against the power of an immediate reward.’’

It’s the fudge vs. broccoli choice: Chocolate’s yum factor tends to beat out the knowledge that veggies bring an eventual reward of lost pounds.

“We all as creatures are hard-wired that way, to give greater value to an immediate reward,’’ Volkow said.

Just how that bit of happiness turns into a habit involves a pleasure-sensing chemical named dopamine. It conditions the brain to want that reward again and again.

Researchers said there are some steps that may help counter your brain’s hold on bad habits. One is to repeat the new behavior — the same routine at the same time of day. Another is to reward yourself for keeping away from the bad behavior.

People tend to overestimate their ability to resist temptation, said experimental psychologist Loran Nordgren, an assistant professor at Northwestern University. “People have this self-control hubris, this belief they can handle more than they can.’’

In one experiment, he measured whether heavy smokers could watch a film that romanticizes the habit without taking a puff. Upping the ante, they would be paid according to their level of temptation: Could they hold a cigarette while watching?

Smokers who had predicted they could resist a lot of temptation tended to hold the unlit cigarette — and were more likely to light up, said Nordgren. He now is studying how recovering drug addicts deal with real-world temptations.

Always snack in front of your favorite TV show? A dopamine-rich part of the brain named the striatum memorizes routines that are linked to getting a particular reward, said Volkow. Eventually, those cues trigger the striatum to make some behaviors almost automatic.

Much of what scientists know about dopamine’s role in habit formation comes from the study of alcohol and drug addiction, but it is a key player in more common habits, too, like overeating.

In fact, for anything that links an action and a reward, “dopamine is indispensable for the formation of these habits,’’ Volkow said.

A movement to pay people for behavior changes may exploit that connection, as some companies offer employees payments or insurance rebates for adopting better habits.