Clinical EEG slowing induced by electroconvulsive therapy is better described by increased frontal aperiodic activity

Sydney E Smith; Vincent Ma; Celene Gonzalez; Angela Chapman; David Printz; Bradley Voytek; Maryam Soltani

doi:10.1038/s41398-023-02634-9

Clinical EEG slowing induced by electroconvulsive therapy is better described by increased frontal aperiodic activity

Transl Psychiatry. 2023 Nov 16;13(1):348. doi: 10.1038/s41398-023-02634-9.

Authors

Sydney E Smith¹, Vincent Ma², Celene Gonzalez³, Angela Chapman⁴, David Printz^{5

6}, Bradley Voytek^#^{7

8

9

10}, Maryam Soltani^#^{5

6}

Affiliations

¹ Neurosciences Graduate Program, University of California, San Diego, La Jolla, CA, USA. s1smith@health.ucsd.edu.
² Los Angeles General Medical Center, Los Angeles, CA, USA.
³ Department of Radiology, University of California, San Diego Health, La Jolla, CA, USA.
⁴ Department of Psychological and Brain Sciences, University of Iowa, Iowa City, IA, USA.
⁵ Department of Psychiatry, VA San Diego Health, San Diego, CA, USA.
⁶ Department of Psychiatry, University of California, San Diego, La Jolla, CA, USA.
⁷ Neurosciences Graduate Program, University of California, San Diego, La Jolla, CA, USA.
⁸ Department of Cognitive Science, University of California, San Diego, La Jolla, CA, USA.
⁹ Halıcıoğlu Data Science Institute, University of California, San Diego, La Jolla, CA, USA.
¹⁰ Kavli Institute for Brain and Mind, University of California, San Diego, La Jolla, CA, USA.

^# Contributed equally.

Abstract

Electroconvulsive therapy (ECT) is one of the most efficacious interventions for treatment-resistant depression. Despite its efficacy, ECT's neural mechanism of action remains unknown. Although ECT has been associated with "slowing" in the electroencephalogram (EEG), how this change relates to clinical improvement is unresolved. Until now, increases in slow-frequency power have been assumed to indicate increases in slow oscillations, without considering the contribution of aperiodic activity, a process with a different physiological mechanism. In this exploratory study of nine MDD patients, we show that aperiodic activity, indexed by the aperiodic exponent, increases with ECT treatment. This increase better explains EEG "slowing" when compared to power in oscillatory peaks in the delta (1-3 Hz) range and is correlated to clinical improvement. In accordance with computational models of excitation-inhibition balance, these increases in aperiodic exponent are linked to increasing levels of inhibitory activity, suggesting that ECT might ameliorate depressive symptoms by restoring healthy levels of inhibition in frontal cortices.

MeSH terms

Depressive Disorder, Treatment-Resistant* / therapy
Electroconvulsive Therapy*
Electroencephalography
Humans

Grants and funding

R01 GM134363/GM/NIGMS NIH HHS/United States