Global field power and low resolution electromagnetic tomography solutions in Alzheimer's disease

Abstract Brain electrophysiological characteristics of Alzheimer's disease (AD) were investigated by global field power (GFP) and low-resolution electromagnetic tomography (LORETA). GFP measures the energy of the brain electric field. LORETA computes for the smoothest of all possible source configurations throughout the brain volume by minimizing the total source strengths. The study population included a total of 29 AD patients and 15 age-matched controls. Clinical stages were based on the functional assessment staging (FAST). Mild-AD consists of 18 patients with a diagnosis of moderate cognitive decline (Stage 4). Advanced-AD consists of 11 patients with a diagnosis of severe cognitive decline (Stages 5, 6 and 7). Nineteen-channel eye-closed EEG was recorded using Cz reference and artifact-free 20 s were picked up and recomputed vs. average reference. Mild-AD showed lower power at Beta-2 and Beta-3 bands than control, and remarkably, advanced-AD showed lower power at the higher band of Alpha-1 than control. The t -scores of the current density of mild-AD were more reduced in the right frontal and temporal areas than the control at the beta bands, and of advanced-AD, reduced in low temporal area at alpha bands and reduced in temporal and parietal area at beta bands. This result clearly demonstrates the physiological characteristics of the clinical stages in Alzheimer's disease.