title: Stability of clinical condition in mild cognitive impairment is related to cortical sources of alpha rhythms: an electroencephalographic study.
abstract: Previous evidence has shown that resting eyes-closed cortical alpha rhythms are higher in amplitude in mild cognitive impairment (MCI) than Alzheimer's disease (AD) subjects (Babiloni et al. [2006a]: Human Brain Mapp 27:162-172; [2006b]: Clin Neurophysiol 117:252-268; [2006c]: Neuroimage 29:948-964; [2006d]: Ann Neurol 59:323-334; [2006e]: Clin Neurophysiol 117:1113-1129; [2006f]: Neuroimage 31:1650-1665). This study tested the hypothesis that, in amnesic MCI subjects, high amplitude of baseline cortical alpha rhythms is related to long-term stability of global cognition on clinical follow-up. Resting electroencephalographic (EEG) data were recorded in 100 amnesic MCI subjects during eyes-closed condition. EEG rhythms of interest were delta (2-4 Hz), theta (4-8 Hz), alpha1 (8-10.5 Hz), alpha2 (10.5-13 Hz), beta1 (13-20 Hz), and beta2 (20-30 Hz). Cortical EEG sources were estimated by low-resolution brain electromagnetic tomography (LORETA). Global cognition was indexed by mini mental state evaluation (MMSE) score at the time of EEG recordings (baseline) and about after 1 year. Based on the MMSE percentage difference between baseline and 1-year follow-up (MMSEvar), the MCI subjects were retrospectively divided into three arbitrary groups: DECREASED (MMSEvar ≤ -4%; N = 43), STABLE (MMSEvar ≈ 0; N = 27), and INCREASED (MMSEvar ≥ +4%; N = 30). Subjects' age, education, individual alpha frequency, gender, and MMSE scores were used as covariates for statistical analysis. Baseline posterior cortical sources of alpha 1 rhythms were higher in amplitude in the STABLE than in the DECREASED and INCREASED groups. These results suggest that preserved resting cortical neural synchronization at alpha frequency is related to a long-term (1 year) stable cognitive function in MCI subjects. Future studies should use serial MMSE measurements to confirm and refine the present results.
authors.affiliation: Department of Biomedical Sciences, University of Foggia, Foggia, Italy. c.babiloni@unifg.it
authors.forename: Claudio
authors.initials: C
authors.lastname: Babiloni
authors.forename: Giovanni B
authors.initials: GB
authors.lastname: Frisoni
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Vecchio
authors.forename: Roberta
authors.initials: R
authors.lastname: Lizio
authors.forename: Michela
authors.initials: M
authors.lastname: Pievani
authors.forename: Geroldi
authors.initials: G
authors.lastname: Cristina
authors.forename: Claudia
authors.initials: C
authors.lastname: Fracassi
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Vernieri
authors.forename: Guido
authors.initials: G
authors.lastname: Rodriguez
authors.forename: Flavio
authors.initials: F
authors.lastname: Nobili
authors.forename: Raffaele
authors.initials: R
authors.lastname: Ferri
authors.forename: Paolo M
authors.initials: PM
authors.lastname: Rossini
mesh_terms: D000368:Aged; D000513:Alpha Rhythm / Q000502:physiology*; D000544:Alzheimer Disease / Q000503:physiopathology / Q000523:psychology; D003071:Cognition / Q000502:physiology; D060825:Cognitive Dysfunction / Q000503:physiopathology* / Q000523:psychology*; D003344:Cortical Synchronization; D003627:Data Interpretation, Statistical; D039721:Diagnostic and Statistical Manual of Mental Disorders; D018450:Disease Progression; D004569:Electroencephalography; D056344:Executive Function / Q000502:physiology; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008568:Memory / Q000502:physiology; D009483:Neuropsychological Tests