[The baseline EEG traits and the induced EEG changes by chronic antidepressant medication in patients with major depression. Early prediction of clinical outcomes solely based on quantification and mapping of EEG].

Forty patients of typical major depression (DSM-III-R) have been adopted for the present study. Hamilton Rating Scale for Depression (HAM-D) was used for the clinical assessment of depressive symptoms, and the patients were followed up at least for four weeks. All the patients were confirmed to be right-handed. The baseline EEGs were compared with age-matched normal subjects (N = 38; all right handed). The differences between depressive patients and normal subjects were less theta activity, more fast activity in anterior part of both hemispheres and in posterior part of the right hemisphere in the depressive patients than in the normal subjects. As a preliminary study, amitriptyline 25 mg was single dose administered and EEGs were recorded before and 1, 3 and 6 hours after the first drug administration in normal male volunteers (N = 6; right-handed). EEG changes of after the medication from the baseline were significant increase of theta and decrease of alpha activity, increase of beta activity was not significant changes. Particularly EEG changes of after 3 hour's administration showed the typical thymoleptic reaction type. EEG changes in patients from the baseline EEG after the first medication were similar to normal subjects. The patients (N = 21) were divided into two groups based on the changes of HAM-D score during four-weeks' treatment; therapy-responsive and therapy-resistant groups. EEG changes after the first single dose administrations in the former were compared with the latter of two patients' groups. Both groups have shown an increase of theta and a decrease of alpha activity. There was more evident alpha increase in therapy-responsive patients than in therapy-resistant ones. However, there were significant differences in amitriptyline-induced EEG changes particularly in beta frequency band; therapy-responsive group showed an increase of beta activity, while therapy-resistant showed no or little change. Using discriminant analysis, the overall hitting ratio of the EEG prediction for therapy-responsive and therapy-resistant group was calculated as 85% at 3 hours after the initiation of antidepressant medication. If EEG mapping, particularly the mapping of differences between pre- and post-drug EEGs, is used to illustrate the EEG responses against antidepressant medication, it will be quite useful to discriminate therapy-resistant patients from therapy-responsive ones in very early stage of the drug treatment.