Topographical changes in alpha power in medicated and unmedicated schizophrenics during digits span reverse matching test.

The topographical distribution of alpha power reduction was compared in nine unmedicated schizophrenics (predominantly never-treated), 17 medicated schizophrenics, and 15 normal controls. The task involved four procedures: (1) listening to signal sound, (2) listening to digits for memorization, (3) after listening, and (4) listening to digits for recognition. The electroencephalograms (EEGs) during each procedure were analyzed with Fast Fourier Transformation and compared with EEGs at rest. While listening to the digits, medicated schizophrenics showed less alpha power reduction than normal controls and unmedicated schizophrenics. In addition, there were correlations found between the degree of alpha power reduction and medication dose, and score of chronic symptoms. These suggest that patients with different clinical backgrounds have differing cerebral activity.