P3 and rCBF characteristics of patients with major depression in depressed and remitted phases

Background. Depressive episodes are likely to be associated with reversible brain states. These can be examined with a variety of methods, such as ERP, SPECT or PET. Previous studies have reported that P300 amplitudes reduced in the depressed phase and recovered in the remitted phase. There have been some reports that anterior cingulate blood flow reduced in the depressed phase and recovered in the remitted phase. Method. Five right-handed depressed patients were studied in both the depressed and remitted phases by using I-123-IMP SPECT and ERP. Results. There were no significant differences in regional cerebral blood flows (rCBFs) between the depressed and remitted phases. Four of the five subjects showed parallel changes of rCBF in the anterior cingulate, frontal cortex and basal ganglia between the depressed and remitted phases. The changes of P300 amplitude at P4 between the depressed and remitted phases had positive correlation with those of rCBFs in the bilateral thalamus and right cingulate. The changes of P300 amplitude at Pt had negative correlation with those of rCBFs in the right frontal and left basal ganglia, In the anxious type, P300 amplitudes at Pt decreased and rCBFs in the frontal cortex and anterior cingulate increased. Conversely, in the retarded type, P300 amplitudes at Pt increased and rCBFs in the frontal cortex and anterior cingulate decreased. Conclusion. Our findings of the parallel changes of rCBF in the anterior cingulate, frontal cortex and basal ganglia between the depressed and remitted phases indicates that these neuroanatomical circuits may be involved in depression. The anxious type may be different from the retarded type in the changes of rCBF between the depressed and remitted phases in the frontal cortex and anterior cingulate, and in the changes of P300 amplitudes.