Psychiatry Investig.  2021 Jun;18(6):486-499. 10.30773/pi.2020.0438.

Systematic Review of the Neural Effect of Electroconvulsive Therapy in Patients with Schizophrenia: Hippocampus and Insula as the Key Regions of Modulation

Affiliations
  • 1Department of Psychiatry, Seoul National University College of Medicine, Seoul, Republic of Korea
  • 2Department of Neuropsychiatry, Seoul National University Hospital, Seoul, Republic of Korea
  • 3Department of Brain and Cognitive Sciences, Seoul National University College of Natural Sciences, Seoul, Republic of Korea
  • 4Institute of Human Behavioral Medicine, SNU-MRC, Seoul, Republic of Korea

Abstract


Objective
Electroconvulsive therapy (ECT) has been the most potent treatment option for treatment-resistant schizophrenia (TRS). However, the underlying neural mechanisms of ECT in schizophrenia remain largely unclear. This paper examines studies that investigated structural and functional changes after ECT in patients with schizophrenia.
Methods
We carried out a systematic review with following terms: ‘ECT’, ‘schizophrenia’, and the terms of various neuroimaging modalities.
Results
Among the 325 records available from the initial search in May 2020, 17 studies were included. Cerebral blood flow in the frontal, temporal, and striatal structures was shown to be modulated (n=3), although the results were divergent. Magnetic resonance spectroscopy (MRS) studies suggested that the ratio of N-acetyl-aspartate/creatinine was increased in the left prefrontal cortex (PFC; n=2) and left thalamus (n=1). The hippocampus and insula (n=6, respectively) were the most common regions of structural/functional modulation, which also showed symptom associations. Functional connectivity of the default mode network (DMN; n=5), PFC (n=4), and thalamostriatal system (n=2) were also commonly modulated.
Conclusion
Despite proven effectiveness, there has been a dearth of studies investigating the neurobiological mechanisms underlying ECT. There is preliminary evidence of structural and functional modulation of the hippocampus and insula, functional changes in the DMN, PFC, and thalamostriatal system after ECT in patients with schizophrenia. We discuss the rationale and implications of these findings and the potential mechanism of action of ECT. More studies evaluating the mechanisms of ECT are needed, which could provide a unique window into what leads to treatment response in the otherwise refractory TRS population.

Keyword

Electroconvulsive therapy, Schizophrenia, Treatment-resistant schizophrenia, Hippocampus, Insula.
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