Development of 1H MRS biomarkers for tracking early predementia Alzheimer disease

Single-voxel ¹H magnetic resonance spectroscopy (¹H MRS) is a magnetic resonance technique for quantifying certain metabolites in the brain that are differentially associated with cellular, molecular, and clinical alterations characteristic of the pathophysiologic development and progression of Alzheimer disease (AD).^1,2 Specifically, lower N-acetylaspartate to creatine ratios (NAA/Cr) have been associated with increased levels of phosphorylated tau seen in pretangle, early neuritic, and mature state neurofibrillary tangle pathology but not with the extracellular neurofibrillary "ghost" tangle tau pathology that occurs later in the disease course.^1,2 Lower NAA/Cr has also been associated with a loss of synaptic integrity measured with SV2A synaptic vesicle protein.² In addition, higher myo-inositol to Cr ratios (mI/Cr) are associated with increased densities of diffuse, neuritic, and cored β-amyloid plaques.^1,2 The accumulation of early tau and β-amyloid pathology, as well as loss of synaptic function, precede the onset of cognitive symptoms and dementia in older individuals across the AD continuum; and their association with NAA/Cr and NAA/mI ratios on ¹H MRS imaging supports their use as biomarkers able to detect the earliest stages of AD pathophysiology.²

from Neurology recent issues http://bit.ly/2Rnj3mq