Cao G, et al. - This study is performed to examine whether brain gamma-aminobutyric acid (GABA) levels in patients with relapsing-remitting multiple sclerosis (RRMS) are abnormal compared with healthy controls, and their relationship to cognitive function in RRMS. The outcome of this study exhibits that abnormalities of the GABAergic system may be present in the pathogenesis of RRMS and recommends a potential link between regional GABA levels and cognitive impairment in patients with RRMS.