Frontal lobe GABA levels in cocaine dependence: a two-dimensional, J-resolved magnetic resonance spectroscopy study

Non-invasive measures of brain gamma-aminobutyric acid (GABA) concentrations may be especially useful in the identification of cocaine-related changes in brain chemistry that can be used to guide the development of future treatments for cocaine-dependent persons. This study assessed whether brain GABA levels in cocaine-dependent subjects with and without an alcohol disorder differ from GABA levels in healthy comparison subjects. Two-dimensional, proton magnetic resonance spectroscopy was used to determine GABA levels in the left prefrontal lobe of cocaine-dependent subjects (N = 35) recruited from a National Institute on Drug Abuse (NIDA)-sponsored treatment trial of cocaine dependence and a comparison group (N = 20). At treatment baseline, mean GABA concentrations were 0.93 +/- 0.27 mM/kg in cocaine-dependent subjects and 4.32 +/- 0.44 mM/kg in the comparison sample (t [d.f. = 53] = 3.65, P < 0.001). Cocaine-dependent subjects with a history of a co-morbid alcohol disorder (N = 23) had significantly lower baseline GABA levels (0.87 mM/kg) (t [d.f. = 41] = 4.31, P < 0.001) than the comparison group. However, cocaine-dependent subjects without an alcohol disorder (N = 12) also had lower GABA levels (1.04 mM/kg) than the comparison subjects (t [d.f. = 30] = 2.09, P = 0.045), suggesting that cocaine dependence alone can decrease GABA levels. (C) 2003 Elsevier Ireland Ltd. All rights reserved.