Electromagnetic signatures of the preclinical and prodromal stages of Alzheimer's disease

• Published in: Brain (London, England : 1878) Vol. 141; no. 5; pp. 1470 - 1485
• Main Authors: Nakamura, Akinori, Cuesta, Pablo, Fernández, Alberto, Arahata, Yutaka, Iwata, Kaori, Kuratsubo, Izumi, Bundo, Masahiko, Hattori, Hideyuki, Sakurai, Takashi, Fukuda, Koji, Washimi, Yukihiko, Endo, Hidetoshi, Takeda, Akinori, Diers, Kersten, Bajo, Ricardo, Maestú, Fernando, Ito, Kengo, Kato, Takashi
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 01.05.2018
• Subjects: Aged; Aged, 80 and over; Alzheimer Disease - complications; Alzheimer Disease - diagnostic imaging; Amyloid beta-Peptides - metabolism; Analysis of Variance; Aniline Compounds - pharmacokinetics; Brain - diagnostic imaging; Brain - physiopathology; Brain Mapping; Cognitive Dysfunction - diagnostic imaging; Cognitive Dysfunction - etiology; Disease Progression; Female; Humans; Magnetic Resonance Imaging; Magnetoencephalography - methods; Male; Neuropsychological Tests; Original; Positron-Emission Tomography; Prodromal Symptoms; Psychiatric Status Rating Scales; Thiazoles - pharmacokinetics; regional power spectrum; resting state; amyloid imaging; Alzheimer's disease continuum; magnetoencephalography
• ISSN: 0006-8950; 1460-2156
• DOI: 10.1093/brain/awy044

Biomarkers relevant to the pre-dementia stages of Alzheimer's disease are needed. Using MEG, PET, and MRI, Nakamura et al. disentangle resting state regional spectral patterns in cognitively normal subjects and individuals with mild cognitive impairment into MEG signatures related to Aβ deposition, disease progression, or changes non-specific to Alzheimer's disease. Abstract Biomarkers useful for the predementia stages of Alzheimer's disease are needed. Electroencephalography and magnetoencephalography (MEG) are expected to provide potential biomarker candidates for evaluating the predementia stages of Alzheimer's disease. However, the physiological relevance of EEG/MEG signal changes and their role in pathophysiological processes such as amyloid-β deposition and neurodegeneration need to be elucidated. We evaluated 28 individuals with mild cognitive impairment and 38 cognitively normal individuals, all of whom were further classified into amyloid-β-positive mild cognitive impairment (n = 17, mean age 74.7 ± 5.4 years, nine males), amyloid-β-negative mild cognitive impairment (n = 11, mean age 73.8 ± 8.8 years, eight males), amyloid-β-positive cognitively normal (n = 13, mean age 71.8 ± 4.4 years, seven males), and amyloid-β-negative cognitively normal (n = 25, mean age 72.5 ± 3.4 years, 11 males) individuals using Pittsburgh compound B-PET. We measured resting state MEG for 5 min with the eyes closed, and investigated regional spectral patterns of MEG signals using atlas-based region of interest analysis. Then, the relevance of the regional spectral patterns and their associations with pathophysiological backgrounds were analysed by integrating information from Pittsburgh compound B-PET, fluorodeoxyglucose-PET, structural MRI, and cognitive tests. The results demonstrated that regional spectral patterns of resting state activity could be separated into several types of MEG signatures as follows: (i) the effects of amyloid-β deposition were expressed as the alpha band power augmentation in medial frontal areas; (ii) the delta band power increase in the same region was associated with disease progression within the Alzheimer's disease continuum and was correlated with entorhinal atrophy and an Alzheimer's disease-like regional decrease in glucose metabolism; and (iii) the global theta power augmentation, which was previously considered to be an Alzheimer's disease-related EEG/MEG signature, was associated with general cognitive decline and hippocampal atrophy, but was not specific to Alzheimer's disease because these changes could be observed in the absence of amyloid-β deposition. The results suggest that these MEG signatures may be useful as unique biomarkers for the predementia stages of Alzheimer's disease.