Evidence of Biochemical and Biomagnetic Interactions in Alzheimer’s Disease: An MEG and MR Spectroscopy Study

Abstract

Background: Several neuroimaging studies have shown reliable differences between Alzheimer’s disease (AD) patients and age-matched controls. However, few studies have demonstrated the interactions between neuroimaging methods for the diagnoses of AD. Objective: In this study, we try to elucidate the complementary nature of magnetoencephalography (MEG) and magnetic resonance spectroscopy (MRS) examinations in the assessmentof AD. Methods: Ten patients fulfilling the NINCDS-ADRDA criteria of probable AD, and 10 elderly individuals with no history of neurological or psychiatric illness serving as age-matched controls participated in the study. All patients and controls received an MRS, MEG and neuropsychological assessment. MEG data were obtained in the context of a working memory task, previously utilized in a similar sample of patients. Results: The AD group showed a reduced number of activity sources over left temporoparietal areas during the late portion of the evoked magnetic field (between 400–800 ms), as well as a bilateral temporoparietal increase in creatine and myoinositol concentrations, and in the myoinositol/N-acetyl-aspartate ratio. The combination of the variables ‘number of dipoles during the late portion of the evoked magnetic field’ and ‘myoinositol/N-acetyl-aspartate ratio’ accounted for 65% of the variance of the Mini Mental State Examination scores. Conclusions: These results highlight the importance of assessing the complex brain pathology underlying AD by utilizing multiple brain examination modalities in a coordinate approach.

A Comprehensive Review of Magnetoencephalography (MEG) Studies for Brain Functionality in Healthy Aging and Alzheimer's Disease (AD)

“…In memory based task, a relation between hippocampal atrophy and the degree of neurophysiological activity in the left temporal lobe has been demonstrated (Maestú et al, 2003 ). A reduced MEG response during the retention period of a working memory task was observed in AD and the findings were in line with MRS data (Maestu et al, 2005 ). Task based evoked potential analysis can also differentiate between AD and HC subjects but the clarification of changes may be difficult depending upon task performance and level of concentration of the subjects during experiment (Dickerson, 2007 ).…”

“…Concentration of NAA decreases and mI increases with the progression of AD. Integrated study of MEG with MRS has been performed to associate altered brain oscillations with neurochemical changes (Maestu et al, 2005 ). For a working memory task, the AD group showed a reduced number of activity sources over left temporoparietal areas in MEG analysis.…”

“…For correction of MCP, Bonferroni correlation was used while statistically validating MEG-MRS combined study using ANOVA for AD and HC (Maestu et al, 2005 ). In a comparative study of progressive MCI, stable MCI and controls using synchronization likelihood parameter Kruskal–Wallis (KW) test was performed.…”

Complex network analysis of resting state EEG in amnestic mild cognitive impairment patients with type 2 diabetes

“…Besides, the current work revealed that left temporal region was most involved in the abnormal functional connection. Other studies in MCI and AD have also stressed the importance of left temporal region and suggested that left temporal disturbance have been associated with a higher chance of conversion to MCI (Maestú et al, 2005 , 2006 ).…”

Use of magnetoencephalography (MEG) to study functional brain networks in neurodegenerative disorders

“…Combining delta dipole density with measures from MRI spectroscopy (myoinositol/N-acetyl aspartate) a sensitivity of 90% and a specificity of 100% was reported in a small study involving 10 AD patients and 10 controls [39]. The usefulness of combining dipole density during a memory task with measures derived from MRI spectroscopy has been studied by Maestu et al [40]. Osipova et al [41] used minimum current estimates to study the sources of the alpha rhythm in AD patients and healthy controls.…”