Decreased EEG synchronization and its correlation with symptom severity in Alzheimer's disease.

BACKGROUND Global field synchronization (GFS) has recently been introduced to measure functional synchronization in frequency-domain EEG data. This study explored GFS values and its clinical significance in patients with Alzheimer's disease (AD). METHOD EEGs were recorded from 22 AD patients and 23 age-matched healthy controls. GFS values were computed in the delta, theta, alpha, beta1, beta2, beta3, gamma, and full frequency bands. The Mini-Mental Status Examination (MMSE) and the Clinical Dementia Rating scale (CDR) were used to assess the symptom severity in AD patients. RESULTS GFS values in the beta1, beta2, beta3, and full bands were lower in AD patients than in healthy controls. GFS values in the alpha, beta1, beta2, beta3, and full bands were positively correlated with the MMSE and CDR scores in combined group (AD patients and healthy controls). In AD patients, GFS values were positively correlated with MMSE scores in the beta1, beta 3, and full bands, and with CDR scores in the delta band. CONCLUSION GFS values were significantly lower in AD patients than in healthy controls, and they were positively correlated with MMSE and CDR scores. Our results suggest that GFS values are a useful biological correlate of cognitive decline in AD patients.