Abstract
Introduction: Electroconvulsive therapy (ECT) has antidepressant effects, but it also has possible cognitive side effects. The effects of ECT on neuronal oscillatory pattern and phase synchronization, and the relationship between clinical response or cognitive change and electroencephalogram (EEG) measurements remain elusive.Methods: Individuals with unipolar depressive disorder receiving bilateral ECT were recruited. Five minutes of resting, eyes-closed, 19-lead EEG recordings were obtained before and after a course of ECT. Non-overlapping 60 artifact-free epocs of 2-s duration were used for the analyses. We used exact low resolution electromagnetic tomography (eLORETA) to compute the whole-brain three-dimensional intracortical distribution of current source density (CSD) and phase synchronization among 28 regions-of-interest (ROIs). Paired t-tests were used to identify cortical voxels and connectivities showing changes after ECT. Montgomery Asberg Depression Rating Scale (MADRS) and Mini-Mental State Examination (MMSE) were used to evaluate the severity of depression and the global cognitive function. Correlation analyses were conducted to identify the relationship between changes in the EEG measurements and changes in MADRS or MMSE.Results: Thirteen depressed patients (five females, mean age: 58.4 years old) were included. ECT increased theta CSD in the anterior cingulate cortex (ACC), and decreased beta CSD in the frontal pole (FP), and gamma CSD in the inferior parietal lobule (IPL). ECT increased theta phase synchronization between the posterior cingulate cortex (PCC) and the anterior frontal cortex, and decreased beta phase synchronization between the PCC and temporal regions. A decline in beta synchronization in the left hemisphere was associated with cognitive changes after ECT.Conclusion: ECT modulated resting-state EEG oscillatory patterns and phase synchronization in central nodes of the default mode network (DMN). Changes in beta synchronization in the left hemisphere might explain the ECT-related cognitive side effects.
Highlights
Electroconvulsive therapy (ECT) has antidepressant effects, but it has possible cognitive side effects
After ECT, the total Montgomery Asberg Depression Rating Scale (MADRS) score was significantly reduced from TP1 to TP2 [TP1: 30.3 (8.6), TP2: 6.5 (6.3), df = 12, t = 9.04, p < 0.001], whereas the total Mini-Mental State Examination (MMSE) score did not change [TP1: 27.0 (3.0), TP2: 26.3 (2.9), df = 11, t = 0.76, p = 0.46]
The current study revealed that ECT increased theta activity in the anterior cingulate cortex (ACC)/medial prefrontal cortex (MPFC), decreased beta activity in the frontal pole (FP), and decreased gamma activity in the inferior parietal lobule (IPL)
Summary
Electroconvulsive therapy (ECT) has antidepressant effects, but it has possible cognitive side effects. The effects of ECT on neuronal oscillatory pattern and phase synchronization, and the relationship between clinical response or cognitive change and electroencephalogram (EEG) measurements remain elusive. Electroconvulsive therapy (ECT) is the most effective antidepressant treatment (Kellner et al, 2012), but it has potential cognitive side effects (Semkovska and McLoughlin, 2010). Studies investigating the effects of ECT on electrophysiological measurements date back to the 1930s. The number of studies examining the electrophysiological effects of ECT is still small compared to other modalities, such as magnetic resonance imaging (MRI; Abbott et al, 2014). The relationship between changes in clinical response and/or cognitive function and changes in EEG measurements remains elusive
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