Clinical and Imaging Correlations of Generalized Hypersynchronous Alpha Activity in Human EEG Recordings, During Alertness.

PURPOSE: In a considerable percentage of individuals with a detectable alpha rhythm in their EEG, bursts of generalized hypersynchronous alpha activity (GHSAA) may occur, during alertness. The aim of this study was to examine whether appearance of GHSAA, which probably generates from transcortical circuitry, shows any correlation with demographic characteristics, underlying normal or abnormal pathophysiology, or substances in use.

METHODS: The authors retrospectively reviewed 441 EEG recordings performed in their laboratory during a 1-year period for presence of GHSAA, concomitantly collecting data that concerned symptoms, diagnosis, imaging, medication, and demographics. Recordings in mental states other than alertness were excluded from the sample.

RESULTS: Generalized hypersynchronous alpha activity was found in 22.95% of the study population. Its occurrence was diminished in male gender (P < 0.001), older age (Kendall tau, 0.16; P < 0.0001), and disorders involving structural abnormalities like brain lesions or neurodegeneration (P < 0.02). Dementia, Parkinson disease, and psychoses showed individually a trend towards lower GHSAA presence.

CONCLUSIONS: In the sample, the presence of GHSAA was commonly observed in the cohort of patients without abnormalities in their neuroimaging studies. Generalized hypersynchronous alpha activity is a finding of youth and requires a properly functioning cerebral cortex in order to emerge. Female preponderance may signify underlying trangender differences in alpha rhythm generators. These preliminary results indicate that the significance of GHSAA alterations deserves more thorough evaluation in larger groups of patients suffering from a variety of different neuropsychiatric disorders.