Abnormally high EEG alpha synchrony during working memory maintenance in twins discordant for schizophrenia.

Background: The present analyses aimed to test the prediction that schizophrenia patients and their non-schizophrenic co-twins would display reduced efficiency of the neurocognitive mechanisms subserving active maintenance of spatial information in working memory.

Methods: Upper alpha frequency band EEG event-related desynchronization and synchronization (ERD/ERS) were calculated as percent changes in power relative to an inter-trial baseline across 4 memory loads in a spatial delayed-response task.

Results: During the delay, the diagnostic groups showed equivalent ERD/ERS activity over posterior scalp regions at the lowest memory load; however, as memory load increased, patients, and to an intermediate degree, their non-schizophrenic co-twins (monozygotic and dizygotic pairs collapsed together), showed significantly greater increases in ERD/ERS amplitude as compared with controls.

Conclusions: These findings demonstrate abnormally increased ERD/ERS amplitudes with increasing memory load in patients with schizophrenia and their co-twins, consistent with inefficiency of the neurocognitive mechanisms supporting active maintenance of information across a delay.