Anterior cingulum white matter is altered in tobacco smokers.

BACKGROUND AND OBJECTIVES

The anterior cingulate cortex (ACC) is hypothesized to be involved in decision making and emotion regulation. Previous observations of drug dependent individuals indicate that substance dependence may be associated with cingulum white matter abnormalities. The present study evaluated cingulum white matter in cigarette smokers.

METHODS

Diffusion tensor imaging (DTI) in adult tobacco smokers and healthy non-smoker controls (total N = 70) was performed in a 3T Siemens Trio MRI scanner.

RESULTS

Analyses of DTI tractography of the cingulum in tobacco-smoking individuals and controls indicated that tobacco abusers have significantly reduced fractional anisotropy (FA) in the right cingulum. In addition, FA in the left cingulum white matter was negatively associated with the number of cigarettes smoked per day and the Fagerstrom test for nicotine dependence, a self-report measure of tobacco dependence severity.

CONCLUSIONS

The white matter of the cingulum is altered in a non-symmetrical way in tobacco smokers. An inverse relationship between FA and reported number of cigarettes per day was observed. Previous studies have also noted altered neural connectivity in cigarette smokers using similar methods. Similar white matter differences in the cingulum have been observed in methamphetamine dependent individuals and patients with dementia, which suggests that the cingulum may be altered by mechanisms not specific to tobacco exposure.

SCIENTIFIC SIGNIFICANCE

By better understanding the effects of tobacco abuse on the brain, we hope to gain insight into how drug dependence influences the neurological foundations of behavior.