Average evoked responses in a rapidly cycling manic-depressive patient

A patient with unusually regular and rapid switches from mania to depression was studied for 113 consecutive days through five switches. Average evoked responses (AERs) to four intesities of light were recorded from vertex and occipital leads; telemetered activity records and behavioral ratings were also collected. Late AER components (P200) tended to change amplitude synchronously with the switches, vertex P200 amplitude decreased and occipital P200 amplitude increased in mania. Urinary MHPG changes paralleled the changes in P200 amplitude. Early AER components (P100) and especially the amplitude/intesity slope measures for P100 decreased about 8-10 days before a switch from depression to mania. Cross-spectral and linear regression analysis helped confirm these observations. The results, taken together with AER data in recent L-dopa studies, were consistent with catecholamine potentiation prior to the switch process from depression into mania.