Chronic Cigarette Smoking in Healthy Middle-Aged Individuals Is Associated With Decreased Regional Brain N-acetylaspartate and Glutamate Levels.

BackgroundCigarette smoking is associated with metabolite abnormalities in anterior brain regions, but it is unclear if these abnormalities are apparent in other regions. Additionally, relationships between regional brain metabolite levels and measures of decision making, risk taking, and impulsivity in smokers and nonsmokers have not been investigated.MethodsIn young to middle-aged (predominately male) nonsmokers (n = 30) and smokers (n = 35), N-acetylaspartate (NAA), choline-containing compounds, creatine-containing compounds (Cr), myo-inositol (mI), and glutamate (Glu) levels in the anterior cingulate cortex and right dorsolateral prefrontal cortex (DLPFC) were compared via 4-tesla proton single volume magnetic resonance spectroscopy. Groups also were compared on NAA, choline-containing compounds, Cr, and mI concentrations in the gray matter and white matter of the four cerebral lobes and subcortical nuclei/regions with 1.5-tesla proton magnetic resonance spectroscopy. Associations of regional metabolite levels with neurocognitive, decision-making, risk-taking, and self-reported impulsivity measures were examined.ResultsSmokers showed lower DLPFC NAA, Cr, mI and Glu concentrations and lower lenticular nuclei NAA level; smokers also demonstrated greater age-related decreases of DLPFC NAA and anterior cingulate cortex and DLPFC Glu levels. Smokers exhibited poorer decision making and greater impulsivity. Across the sample, higher NAA and Glu in the DLPFC and NAA concentrations in multiple lobar gray matter and white matter regions and subcortical nuclei were associated with better neurocognition and lower impulsivity.ConclusionsThis study provides additional novel evidence that chronic smoking in young and middle-aged individuals is associated with significant age-related neurobiological abnormalities in anterior frontal regions implicated in the development and maintenance of addictive disorders