Reduced GABA levels correlate with cognitive impairment in relapsing-remitting multiple sclerosis

To investigate whether cognitive impairment in relapsing-remitting multiple sclerosis (RRMS) is associated with alterations in brain gamma-aminobutyric acid (GABA) levels, 31 RRMS patients and 26 healthy controls underwent 3T ¹H MRS and neuropsychologic assessment. GABA levels were quantified in the posterior cingulate cortex (PCC), the medial prefrontal cortex (mPFC) and left hippocampus (LHC). Patients showed reduced GABA+ in PCC and LHC, and reduced GABA+ levels correlated with cognitive function. This study demonstrates that abnormalities of the GABAergic system may be an important neurochemical mechanism of cognitive impairment in RRMS.