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Abstract:
Background: For preclinical stages of Alzheimer’s disease (AD), the
biomarker potential of in vivo measures of the inhibitory neurotransmitter g -aminobutyric acid (GABA) has not yet been explored.
Methods: We measured GABA, glutamate+glutamine (Glx) and N-acetyl-aspartate (NAA) levels by single-voxel MEGA-PRESS magnetic resonance spectroscopy in the posterior cingulate cortex (PCC) of 22 elderly healthy control subjects (HCS) and 16 age-, gender-, and education-matched patients with amnestic mild cognitive impairment (aMCI). Participants underwent PittsburghCompound B positron emission tomography(PiB-PET), apolipo-protein E (APOE) genotyping, and neuropsychological examination.
Results: In the PCC, GABA, Glx and NAA levels were lower in aMCI pa-
tients. Neurotransmitter levels and NAAwere neither correlated to global or local b -amyloid status nor to APOE genotype, but GABA, Glx, and NAA levelswere positivelycorrelated toverbal learningscores.
Conclusions: Reductions in PCC GABA, Glx and NAA levels may serve as functional biomarkers for cognitive impairment in aMCI. Since they do not seem to reflect amyloid b deposition (or APOE genotype), they are less likely biomarker candidates for preclinical AD.
