Neuronal viability/astrocyte activity ratio in the dorsolateral prefrontal cortex as a biomarker of Alzheimer's dementia: a proton magnetic resonance spectroscopy study.

N-acetyl-aspartate (NAA) and myo-inositol (mI) are neurometabolites reflecting neuronal viability and astrocyte activity, respectively. These are quantified using proton magnetic resonance spectroscopy (1H-MRS) and may be biomarkers for Alzheimer's disease dementia (AD). Our objectives were: 1) Compare dorsolateral prefrontal cortex (DLPFC) NAA and mI levels between AD and cognitively healthy control participants (HC) 2) assess if NAA/mI ratio can distinguish groups, and 3) explore the relationship between metabolites and cognition. The study included 64 participants over 55, 41 with AD. Bilateral DLPFC NAA and mI levels were quantified using 3 T 1H-MRS and normalized to H2O. NAA and NAA/mI ratio were lower in AD vs. HC. mI was unchanged. The NAA/mI ratio at a cut-off value of 1.69 showed 59% sensitivity and 87% specificity at distinguishing AD from HC. NAA was associated positively with cognition. In conclusion, DLPFC metabolite changes suggest altered mitochondrial function in AD. NAA/mI ratio shows good specificity in distinguishing AD from HC, suggesting its role in complementing other biomarkers. Future studies should evaluate NAA/mI ratio with other disease specific biomarkers.