Shared and Disorder-Specific Event-Related Brain Oscillatory Markers of Attentional Dysfunction in ADHD and Bipolar Disorder

Giorgia Michelini,Jonna Kuntsi,Philip Asherson,Viryanaga Kitsune,Isabella Vainieri,Georgina M Hosang,Daniel Brandeis

doi:10.1007/s10548-018-0625-z

Abstract

Attention-deficit/hyperactivity disorder (ADHD) and bipolar disorder (BD) often present with overlapping symptoms and cognitive impairments, such as increased fluctuations in attentional performance measured by increased reaction-time variability (RTV). We previously provided initial evidence of shared and distinct event-related potential (ERP) impairments in ADHD and BD in a direct electrophysiological comparison, but no study to date has compared neural mechanisms underlying attentional impairments with finer-grained brain oscillatory markers. Here, we aimed to compare the neural underpinnings of impaired attentional processes in ADHD and BD, by examining event-related brain oscillations during a reaction-time task under slow-unrewarded baseline and fast-incentive conditions. We measured cognitive performance, ERPs and brain-oscillatory modulations of power and phase variability in 20 women with ADHD, 20 women with BD (currently euthymic) and 20 control women. Compared to controls, both ADHD and BD groups showed increased RTV in the baseline condition and increased RTV, theta phase variability and lower contingent negative variation in the fast-incentive condition. Unlike controls, neither clinical group showed an improvement from the slow-unrewarded baseline to the fast-incentive condition in attentional P3 amplitude or alpha power suppression. Most impairments did not differ between the disorders, as only an adjustment in beta suppression between conditions (lower in the ADHD group) distinguished between the clinical groups. These findings suggest shared impairments in women with ADHD and BD in cognitive and neural variability, preparatory activity and inability to adjust attention allocation and activation. These overlapping impairments may represent shared neurobiological mechanisms of attentional dysfunction in ADHD and BD, and potentially underlie common symptoms in both disorders.

Highlights

The abilities to regulate alertness and sustain attention are essential for efficient information processing and behavior (Posner and Petersen 1990)
Post-hoc tests of group effects showed that the attention-deficit/ hyperactivity disorder (ADHD) and the bipolar disorder (BD) groups had significantly increased reaction time variability (RTV) compared to controls in both conditions, but did not differ significantly from one another (Table 2)
The BD group showed a trend-level effect for greater contingent negative variation (CNV) compared to the ADHD group, and a significantly reduced CNV compared to controls (Table 2)

Summary

Introduction

The abilities to regulate alertness and sustain attention are essential for efficient information processing and behavior (Posner and Petersen 1990). ADHD and BD represent distinct disorders, they present with common symptoms of distractibility and difficulty concentrating, which can lead to uncertainty regarding the boundaries of the two disorders (Asherson et al 2014; Kitsune et al 2016). These overlapping symptoms may reflect, at the cognitive level, the common fluctuations in attentional performance and increased RTV displayed by individuals with ADHD and BD (Albaugh et al 2017; Kuntsi et al 2014). Cross-disorder comparisons in ADHD and BD are limited to date (Michelini et al 2016; Rommel et al 2016; Torralva et al 2011)

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