GABA concentrations in the anterior cingulate and dorsolateral prefrontal cortices: Associations with chronic cigarette smoking, neurocognition, and decision making

Abstract

Chronic cigarette smoking is associated with regional metabolite abnormalities in choline‐containing compounds, creatine‐containing compounds, glutamate, and N‐acetylaspartate. The effects of cigarette smoking on anterior frontal cortical gamma‐aminobutyric acid (GABA) concentration are unknown. This study compared chronic smokers (n = 33) and nonsmokers (n = 31) on anterior cingulate cortex (ACC) and right dorsolateral prefrontal cortex (DLPFC) GABA+ (the sum of GABA and coedited macromolecules) concentrations and associations of GABA+ levels in these regions with seven neurocognitive domains of functioning, decision making, and impulsivity measures. Smokers had significantly lower right DLPFC GABA+ concentration than nonsmokers, but groups were equivalent on ACC GABA+ level. Across groups, greater number of days since end of menstrual cycle was related to higher GABA+ level in the ACC but not right DLPFC GABA+ concentration. In exploratory correlation analyses, higher ACC and right DLPFC GABA+ levels were associated with faster processing speed and better auditory‐verbal memory, respectively, in the combined group of smokers and nonsmokers; in smokers only, higher ACC GABA+ was related to better decision making and auditory‐verbal learning. This study contributes additional novel data on the adverse effects of chronic cigarette smoking on the adult human brain and demonstrated ACC and DLPFC GABA+ concentrations were associated with neurocognition and decision making/impulsivity in active cigarette smokers. Longitudinal studies on the effects of smoking cessation on regional brain GABA levels, with a greater number of female participants, are required to determine if the observed metabolite abnormalities are persistent or normalize with smoking cessation.