Asymmetric alternation of the hemodynamic response at the prefrontal cortex in patients with schizophrenia during electroconvulsive therapy: a near-infrared spectroscopy study.

OBJECTIVE: Although electroconvulsive therapy (ECT) is a well-established treatment for psychiatric disorders, its mechanism of action remains unclear. To investigate the cerebral hemodynamic response during ECT, we measured the changes in the regional cerebral blood flow (rCBF) at the bilateral prefrontal cortex (PFC) using near-infrared spectroscopy (NIRS). Method. The participants included eleven patients with schizophrenia and ten patients with mood disorders. The normalized tissue hemoglobin index (nTHI) was used as a sensitive parameter of rCBF by the SRS method and was measured during bilateral ECT using a two-channel NIRS. Results. 1. All patients responded to ECT treatment. 2. The levels of bilateral nTHI indicated a transient decrease during electrical stimulation and immediately were increased at both ictal and post-ictal phases by approximately 20% above baseline. 3. Patients with schizophrenia, but not mood disorders, showed significant asymmetric alteration of nTHI levels (left>right) during both the ictal and post-ictal phases. 4. The asymmetry index of nTHI, which indicates the difference between the left and right sides of the nTHI, was negatively correlated with the period of illness for schizophrenia, although the asymmetry index was not significantly correlated with any other clinical data, such as the effect of ECT treatment. Conclusion. Preliminary data demonstrated that bilateral ECT caused hemodynamic changes in bilateral PFC, and asymmetric alteration was found for schizophrenia, but not for mood disorders. Although further studies are necessary, the asymmetric hemodynamic response by ECT may be associated with the pathophysiology of schizophrenia, especially in the early stages.