Abnormal functional asymmetry and its behavioural correlates in adults with ADHD: A TMS-EEG study

Amir Avnit; Samuel Zibman; Uri Alyagon; Abraham Zangen

doi:10.1371/journal.pone.0285086

Abnormal functional asymmetry and its behavioural correlates in adults with ADHD: A TMS-EEG study

PLoS One. 2023 May 25;18(5):e0285086. doi: 10.1371/journal.pone.0285086. eCollection 2023.

Authors

Amir Avnit^{1

2}, Samuel Zibman^{1

2}, Uri Alyagon^{1

2}, Abraham Zangen^{1

2}

Affiliations

¹ Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
² Zlotowski Centre for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel.

Abstract

Objectives: Abnormal functional brain asymmetry and deficient response inhibition are two core symptoms of attention deficit hyperactivity disorder (ADHD). We investigated whether these symptoms are inter-related and whether they are underlined by altered frontal excitability and by compromised interhemispheric connectivity.

Methods: We studied these issues in 52 ADHD and 43 non-clinical adults by comparing: (1) stop-signal reaction time (SSRT); (2) frontal asymmetry of the N200 event-related potential component, which is evoked during response inhibition and is lateralised to the right hemisphere; (3) TMS-evoked potential (TEP) in the right frontal hemisphere, which is indicative of local cortical excitability; and (4) frontal right-to-left interhemispheric TMS signal propagation (ISP), which is reversely indicative of interhemispheric connectivity.

Results: Compared to controls, the ADHD group demonstrated elongated SSRT, reduced N200 right-frontal-asymmetry, weaker TEP, and stronger ISP. Moreover, in the ADHD group, N200 right-frontal-asymmetry correlated with SSRT, with TEP, and with symptoms severity. Conversely, no relationship was observed between ISP and N200 right-frontal-asymmetry, and both TEP and ISP were found to be unrelated to SSRT.

Conclusions: Our results indicate that abnormal frontal asymmetry is related to a key cognitive symptom in ADHD and suggest that it is underlined by reduced right-frontal excitability.

Copyright: © 2023 Avnit et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Adult
Attention Deficit Disorder with Hyperactivity*
Brain
Brain Mapping
Electroencephalography
Evoked Potentials
Humans

Grants and funding

This study was supported by the MAGNET program of the Israel Innovation Authority under grant number 61450; see https://innovationisrael.org.il/en/. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.