Conversion of MCI to dementia: Role of proton magnetic resonance spectroscopy

Mild cognitive impairment (MCI) represents a heterogeneous croup of cognitive disturbances at high risk of dementia. The amnestic subtype (aMCI) might be a prodromal state of Alzheimer's disease (AD). The aim of this study is the identification, by proton magnetic resonance spectroscopy (H-1 MRS), of modifications in brain metabolites able to detect subjects with aMCI at risk of conversion towards AD. Twenty-five subjects with aMCI and 29 normal elderly were enrolled; they underwent a comprehensive clinical and instrumental assessment, a cerebral H-1 MRS scan to measure N-acetyl aspartate (NAA), choline (Cho), myo-inositol (mI) and creatine (Cr) in the paratrigonal white matter, bilaterally. After 1 year, 5 MCI subjects became demented (progressive MCI, pMCI). Their baseline levels of metabolites were compared with those evaluated in stable MCI (sMCI) and in controls. We observed a significant difference of the NAA/Cr ratio between pMCI (1.48 +/- 0.08) and sMCI (1.65 +/- 0.12) and between pMCI and controls (1.63 +/- 0.16) in the left hemisphere, suggesting that this metabolic alteration can be detected before the clinical appearance of dementia. (c) 2005 Elsevier Inc. All rights reserved.