γ-aminobutyric acid and glutamate/glutamine alterations of the left prefrontal cortex in individuals with methamphetamine use disorder: a combined transcranial magnetic stimulation-magnetic resonance spectroscopy study

BACKGROUND: GABAergic and glutamatergic neurotransmitter systems are critical in the pathophysiology of addiction and represent potential targets for repetitive transcranial magnetic stimulation (rTMS). This study aims to investigate changes in γ-aminobutyric acid (GABA) levels, the combined resonance of glutamate and glutamine (Glx) in the left dorsolateral prefrontal cortex (DLPFC), and cognitive function of patients with methamphetamine dependence following rTMS intervention, using proton magnetic resonance spectroscopy ((1)H MRS). METHODS: Fifty methamphetamine-dependent patients were randomized to a 4-week course of active or sham rTMS, with (1)H MRS measurement of DLPFC GABA and Glx levels relative to n-acetyl-aspartate (NAA) and craving and cognitive function measured at baseline and post-intervention. RESULTS: We observed significant reductions of GABA/NAA concentration in the active group and Glx/NAA concentration in the group receiving sham rTMS. There was a significant association between changes in GABA concentration and problem solving/error monitoring. CONCLUSIONS: The effect of rTMS on cognitive function in individuals with methamphetamine dependence may be related to changes in GABA levels in the prefrontal cortex, and warrants further investigation.