The mechanism of action for ECT in MDD is unclear. Research targeting brain changes in ECT is an important pathway to understanding the mechanism of action for ECT.
Patients with MDD show disruptions in brain functional connectivity as measures by functional magnetic resonance imaging (fMRI). The connectivity abnormalities in MDD have included changes in limbic, cortical and default networks.
Abbott and colleagues recently published an analysis of resting state connectivity changes with ECT in a series of subjects with MDD. Key elements of the design of their study included:
- Subjects: 12 subjects with MDD with an average age of 66 years including three subjects with psychotic depression
- ECT parameters: Subjects received an average of 11 standard right unilateral or bitemporal treatments
- fMRI: Functional connectivity measures were assessed before and after ECT using independent component analysis techniques
- Statistical analysis: Connectivity measures were compared within subjects pre and post ECT using paired t-tests. Additionally, subjects were compared to a group of non-depressed individual using two-sample t-tests
The key findings from the study included:
- At baseline depressed subjects showed deficits in connectivity involving the posterior default mode network, the dorsomedial prefrontal cortex and the dorsolateral prefrontal cortex
- Remission of depression in ECT-treated subjects reversed the baseline deficits in posterior default mode network, the dorsomedial prefrontal cortex and the dorsolateral prefrontal cortex
- Remission with ECT was specifically linked to changes functional connectivity in the dorsomedial prefrontal cortex and the dorsolateral prefrontal cortex
The authors note their findings may be useful in the eventual development of identifying MDD subjects most likely to benefit from ECT. Additionally, they note research into the mechanism of action of ECT may provide insight into less intense and more accessible treatment approaches such as transcranial magnetic stimulation therapies.
This is an important study and holds promise that better targeted treatment for MDD may include non-pharmacologic brain stimulation approaches.
Interested readers can learn more about the specifics of this manuscript by clicking on the link below.
Photo of black-bellied whistling ducks from Venice, FL rookery from the authors files.
Abbott, C., Lemke, N., Gopal, S., Thoma, R., Bustillo, J., Calhoun, V., & Turner, J. (2013). Electroconvulsive Therapy Response in Major Depressive Disorder: A Pilot Functional Network Connectivity Resting State fMRI Investigation Frontiers in Psychiatry, 4 DOI: 10.3389/fpsyt.2013.00010