Having A Hard Time Quitting Cigarettes? It’s All In Your Head

Everyone knows that smoking is bad for you, and the nicotine is a highly addictive drug. Even so, the Office on Smoking and Health of the National Center for Chronic Disease Prevention and Health Promotion estimates that approximately 20.9% of U.S. adults are current smokers. Among those who smoke every day, 40.5% (14.6 million) are trying to quit. However, only about 5% of smokers who try to quit each year succeed in stopping smoking permanently. New research (Neuropsychopharmacology, Mar 14, 2007) suggests that certain brain structures may play a role in why so many people have such a hard time quitting.

Researchers at Duke University studied the brains of smokers using Positron Emission Tomography (PET scans). PET is a noninvasive (doesn’t require surgery) technique that enables neuroscientists to determine which parts of the brain are working during different activities. Prior to the scan, a very small amount of a radioactive substance is attached to glucose, and then injected into the bloodstream of the person being studied. The radioactive molecule travels to the area of interest (in this case, the brain) and is detected by the PET scanner. The resulting 3-D image of the brain is projected on a computer screen. Within the image, different colors or degrees of brightness indicate different levels of tissue or organ function. Areas of high radioactivity “light up”, and are associated with increased brain activity.

In the smoking study, PET scans showed that three brain regions demonstrated changes in activity when smokers craved cigarettes. Interestingly, different brain regions were related to specific reasons reported by the subjects for why they smoke.

People who smoked to calm down when they were stressed out showed decreased activity in the area of the brain known as the thalamus. The thalamus is an information relay center in the brain which transmits information to and from our sensory organs (eye, ears, etc.) and our muscles. In addition, (and more relevant to the study findings), the thalamus regulates our levels of arousal (sleep/wakefulness), awareness and activity. People who smoke and have decreased thalamic activity may experience a greater ability to focus thoughts and feel less overwhelmed.

People who smoked to calm down also showed increased activity in their amygdala. The amygdala helps us to form and store memories associated with emotional events. In addition (and again, most relevant to the study), the amygdala is involved in appetitive conditioning, a psychological term meaning that smokers learn to associate and anticipate that smoking a cigarette will cause a positive calming body effect.

People who smoked to gain a sense of pleasurable relaxation showed increased activity in the striatum. The striatum is involved in planning and controlling movement, learning and memory, as well as our level of motivation to continue a behavior (smoking) to obtain a reward (sense of relaxation). In addition, the striatum serves to decrease activity in the thalamus, which (as mentioned above), increases a sense of calm.

People who smoked to reduce a craving for cigarettes showed activity in the anterior cingulate cortex. This brain structure plays a role in enhancing self-regulation and ability to make decisions, empathy (being sensitive to others’ feelings), and emotion. Activation of the anterior cingulate cortex is also tied to anticipating a reward. People who smoke and have increased activity in the anterior cingulate cortex may feel more in control of themselves and better able to make decisions.

The study found that brain changes are not permanent, but will change as a person becomes more or less dependent on nicotine. This type of brain research may go a long way in developing specific and successful smoking cessation strategies.