Magnetic resonance spectroscopy, magnetic resonance imaging and neuropsychology in persons with vascular cognitive impairment and mild Alzheimer's disease: Will new technology help with old problems?

摘要

This study evaluated the potential of Proton Magnetic Resonance Spectroscopy (1H-MRS) for use in clinical practice to distinguish early Alzheimer's disease (AD) from vascular cognitive impairment (VCI) arising from primarily white matter pathology.; Twenty-nine participants (10 early AD, 11 VCI and 8 age and education matched controls) completed a neuropsychological test battery, whole-brain structural MRI, and 1H-MRS in four brain regions: frontal white matter (FWM), dorsolateral prefrontal cortex (DLPFC), medial temporal lobe (MTL) and motor cortex (MC). Structural neuroanatomical measures included brain parenchymal fraction (measure of whole brain atrophy), ratings of MTL atrophy, hippocampal formation (HF) volume, and total area of white matter lesions (WML).; Neuropsychological findings revealed more significant memory impairment for the AD group. Both AD and VCI subjects had lower scores on tests of executive function than controls. There were no group differences in BPF but, irrespective of group membership, lower BPF was associated with poorer memory and executive functioning. The AD group had higher MTL atrophy ratings and decreased HF size relative to controls while the VCI group was intermediate on these measures and did not differ from the AD group. For the total participant sample, higher MTL atrophy ratings were associated with both poor memory and executive function scores whereas smaller HF size was associated only with poor memory. WML were not exclusive to the VCI group and in the total sample, increased WML levels were associated with poorer executive functioning when persons with less than 1% WMLs were removed. For the 1H-MRS metabolite measures, only Creatine differed between the AD and VCI groups in DLPFC, FWM and MC. Moreover, N-acetyl-aspartate levels for controls only differed from VCI subjects in MC. Occasionally, expected associations between metabolites and neuropsychological measures were evident, but these were inconsistent findings and only in some regions.; Neuropsychological and structural neuroanatomical measures were better able to discriminate between patients with mild AD and VCI in this small, well-characterized memory clinic sample. While 1H-MRS continues to have numerous research applications, the current study suggests that it is yet not ready to be applied clinically for the improvement of diagnostic specificity of dementia.