[The influence of interferon therapy on CNS function--from the aspects of quantitative EEG and biogenic amines]

Various CNS side effects have been reported since interferon (IFN) was introduced for the treatment of chronic active hepatitis C (CAHC) patients. Most reports of EEG changes after IFN therapy were inspective, and there is no report of quantitative EEG analysis. In this study, changes in quantitative EEG and biogenic amines after IFN therapy were studied to enable identification of CNS side effects early in CAHC patients. Before and 7 days after IFN therapy, EEG records and plasma and urinary amines were examined in 36 CAHC patients (46.9 +/- 12.3 years, 29 men and 7 women) who were hospitalized for the IFN therapy. After IFN therapy, no notable change in biogenic amines was recognized. On EEG, 13 patients (39.4%) showed increased slow wave activities and 2 patients (6.1%) showed paroxysmal discharges after IFN therapy. On quantitative EEG, the patients showed significantly increased absolute power in slow alpha, theta and delta bands and decreased absolute power in fast beta band (paired-T test). After IFN therapy, 4 of 36 patients developed psychiatric disorders; 2 patients developed depressive symptoms and 2 other patients developed manic states. One depressive patient and one manic patient had 6 Hz spike and slow waves before IFN therapy. On quantitative EEG, the other manic patient had shown significantly increased absolute power in slow alpha and decreased power in fast alpha and beta bands, and the other depressive patient had shown significantly increased absolute power in fast theta band and decreased power in fast beta band before the development of the psychiatric disorders. These results suggest that the changes of quantitative EEG, between before and 7 days after IFN therapy, can be useful in assessing the risk for the development of psychiatric symptoms induced by IFN therapy. It also suggests that patients with slight EEG abnormality such as a 6 Hz spike and slow waves before IFN therapy need careful observation.