Atypical resting-state gamma band trajectory in adult attention deficit/hyperactivity disorder

László Tombor,János Réthelyi,István Bitter,Pál Czobor,Brigitta Kakuszi,Szilvia Papp

doi:10.1007/s00702-021-02368-2

Abstract

Decreased gamma activity has been reported both in children and adults with attention deficit/hyperactivity disorder (ADHD). However, while ADHD is a lifelong neurodevelopmental disorder, our insight into the associations of spontaneous gamma band activity with age is limited, especially in adults. Therefore, we conducted an explorative study to investigate trajectories of resting gamma activity in adult ADHD patients (N = 42) versus matched healthy controls (N = 59). We investigated the relationship of resting gamma activity (30–48 Hz) with age in four right hemispheric electrode clusters where diminished gamma power in ADHD had previously been demonstrated by our group. We found significant non-linear association between resting gamma power and age in the lower frequency gamma1 range (30–39 Hz) in ADHD as compared to controls in all investigated locations. Resting gamma1 increased with age and was significantly lower in ADHD than in control subjects from early adulthood. We found no significant association between gamma activity and age in the gamma2 range (39–48 Hz). Alterations of gamma band activity might reflect altered cortical network functioning in adult ADHD relative to controls. Our results reveal that abnormal gamma power is present at all ages, highlighting the lifelong nature of ADHD. Nonetheless, longitudinal studies are needed to confirm our results.

Highlights

Attention Deficit/Hyperactivity Disorder (ADHD) is the most prevalent childhood mental disorder, and is characterized by inappropriate inattention, hyperactivity and impulsivity compared to healthy peers
For the analysis of between-group EEG power differences by age, our analyses focused on those electrode clusters in which our group previously reported significant differences between ADHD and controls in resting gamma band power (Tombor et al 2018)
The main finding that we report in this paper is a different developmental path of resting gamma1 (30–39 Hz) power in adult ADHD compared to healthy controls

Summary

Introduction

ADHD is the most prevalent childhood mental disorder, and is characterized by inappropriate inattention, hyperactivity and impulsivity compared to healthy peers. ADHD persists into adulthood with full diagnostic criteria, or with a partial remission and concomitant impairment in circa 50% of cases (Faraone et al 2006). It has an estimated prevalence between 1 and 3% in adults (Bitter et al 2010; Simon et al 2009). Clinical characteristics, and neurocognitive profile of ADHD change over time, there is still a lack of knowledge about the lifespan aspects of the electrophysiological alterations of the disorder (Franke 2018).

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