Breaking bad habits relies on 'stop' and 'go' brain signals

At the beginning of every new year, a lot of us make resolutions whether to quit smoking, eat better, or lose weight.

But by February, many of us have already fallen off the resolution wagon. CBC Radio science columnist Torah Kachur looks at anew study from Duke University involvingsome sugar-happy miceon how and why habits are hard to break.

Why is it so hard to break a bad habit?

There are many reasons. Part of what this new study has shownis that habits are wired into our brains. That's why we can perform a habitual behaviour without thinking about it, and why it's so hard to put them under conscious control.

That's not necessarily a bad thing good habits are an important part of enabling us to do things likeoperate a car, shower, or brush our teeth, and stillhave our brains free to focus on other things. That'sbeen an important adaptation for survival.

Habits are programmed into an area of the brain called the basal ganglia this is quite a complex region of the brain that controls good habits, motor actions, bad habits and compulsive behaviours.

How did the new research explorewhat's happening in our brains?

The new study, recentlypublished in the journal Neuron, explored the different pathways in the brain that cause habits.

The researchersstarted by training mice to develop habits. In this case,they trained the mice to press a lever, and in turn the micereceived sweets. The animals became hooked on pressing the lever because they were rewarded with a sweet treat.

So the researchers decided to look more closely at the brains of the habit-trained mice, compared with untrained mice with no previous sugar habit.

Nicole Calakos is the researcher from Duke University who looked at these mice, and explains what specifically she was looking at in the brain.

"There are two cell types in approximately equal numbers... that more or less have been attributed with giving a 'go' signal to do something, or a 'stop' signal," she said.

So there's the "go" signalwhich you could think of asthe devil on your shoulder that says, "Go ahead it's only one cookie. Or four."

And there is a competing pathway in the same area of the brain that is the "stop" signal think of it as the angel on your shoulder that you might call "willpower."

In untrainedmice, whenthey were given the opportunity to press the lever,the "stop" signal came first. In other words, they were better at resisting, and could resist simply because they hadn't formeda habit.

In the trained mice, the default was "go" their brains told them to press the lever, because they usually do.

What happens in the brain when habits form?

One of the key findings of this study is that thereseemed to be a race between the go and stop signals.

Normally, in order to do something that is not habitual, we have to overcome the stop signal with conscious control.We have to tell our bodies to overcome that inhibition.

So there is a switch once you form a habit that enables you to do things without even thinking about it whether it's agood or bad habit.

What does the new research say about curing bad habits?

It confirms what we intuitively know about our habits.We have to break them bybeginning to re-program our brain to say "stop" first.

But the researchersdid find something really interesting. Themice that could most easily break the habit had a weaker "go"signal.

So breaking a habit meant reducing the activity of the "go" circuitry, to allow the "stop" signals to be the ones to win the race.

This means for most of us interested in breaking bad habits, we have to consciously stop performing the task for a while so that the "go" signal isn't reinforced, and it weakens with time.

Do the study's results apply to serious addictions?

The study focused on a sugar addiction, but to a certain extent its results apply to other addictionsto nicotine or harder drugs, for example.

The researchers were most interested in simplehabits. These do not have or create a chemical dependence in the brain.

When we start talking about drugs like cocaine or nicotine, they have wider effects on the body that a user is also addicted to.

For instance, nicotine is a vasoconstrictor meaning it narrows the blood vessels. So it helps you focus andcalms you down, in addition to the reward pathway in the brain that it triggers.

So giving up smoking is not as easy as just breaking the habit of performing the act of smokingyou also have to kick the addiction to the drug.

But there certainly are components of addiction that are simply habitual for example, a smoker mighthave a coffee and light up a cigarette, even without a big nicotine craving.

Sometimes the solution to that part of the addiction is as simple asdoing something with your hands.

The study is more directly related tocompulsive behaviours, andindividuals who have detrimental habitual behavioursthose with obsessive-compulsive disorder,Tourette'sor autism, for example.

And now that we know significantly more about how the habit forms at the level of the brain circuitry, it will become easier to target those neurons to control the habits.