Modifiable Arousal in Attention-Deficit/Hyperactivity Disorder and Its Etiological Association With Fluctuating Reaction Times

Sarah-Naomi James,Celeste H.M Cheung,Fruhling Rijsdijk,Philip Asherson,Jonna Kuntsi

doi:10.1016/j.bpsc.2016.06.003

Abstract

BackgroundCognitive theories of attention-deficit/hyperactivity disorder (ADHD) propose that high within-subject fluctuations of cognitive performance in ADHD, particularly reaction time (RT) variability (RTV), may reflect arousal dysregulation. However, direct evidence of arousal dysregulation and how it may account for fluctuating RTs in ADHD is limited. We used skin conductance (SC) as a measure of peripheral arousal and aimed to investigate its phenotypic and familial association with RTV in a large sample of ADHD and control sibling pairs. MethodsAdolescents and young adults (N = 292), consisting of 73 participants with ADHD and their 75 siblings, and 72 controls and their 72 siblings, completed the baseline (slow, unrewarded) and fast-incentive conditions of a RT task, while SC was simultaneously recorded. ResultsA significant group-by-condition interaction emerged for SC level (SCL). Participants with ADHD had decreased SCL, compared with controls, in the baseline condition but not the fast-incentive condition. Baseline SCL was negatively associated with RTV, and multivariate model fitting demonstrated that the covariance of SCL with RTV, and of SCL with ADHD, was mostly explained by shared familial effects. ConclusionsADHD is associated with decreased, but modifiable, tonic peripheral arousal. A shared familial cause underlies the relationship between arousal and RTV and between arousal and ADHD. Given the malleability of SCL, if our findings are replicated, it warrants further exploration as a potential treatment target for ADHD.

Highlights

Cognitive theories of attention-deficit/hyperactivity disorder (ADHD) propose that high withinsubject fluctuations of cognitive performance in ADHD, reaction time (RT) variability (RTV), may reflect arousal dysregulation
In a large sibling study of 292 participants, we show that tonic peripheral arousal, indexed with SC level (SCL), is decreased in young people with ADHD during performance on a baseline RT task but normalizes in a faster condition with incentives, indicating modifiable arousal dysregulation in ADHD
We further show that a substantial degree of familial sharing accounts for the significant phenotypic associations between SCL and RT variability (RTV) and between SCL and ADHD

Summary

Introduction

Cognitive theories of attention-deficit/hyperactivity disorder (ADHD) propose that high withinsubject fluctuations of cognitive performance in ADHD, reaction time (RT) variability (RTV), may reflect arousal dysregulation. We used skin conductance (SC) as a measure of peripheral arousal and aimed to investigate its phenotypic and familial association with RTV in a large sample of ADHD and control sibling pairs. METHODS: Adolescents and young adults (N 5 292), consisting of 73 participants with ADHD and their 75 siblings, and 72 controls and their 72 siblings, completed the baseline (slow, unrewarded) and fast-incentive conditions of a RT task, while SC was simultaneously recorded. Participants with ADHD had decreased SCL, compared with controls, in the baseline condition but not the fast-incentive condition. Baseline SCL was negatively associated with RTV, and multivariate model fitting demonstrated that the covariance of SCL with RTV, and of SCL with ADHD, was mostly explained by shared familial effects. CONCLUSIONS: ADHD is associated with decreased, but modifiable, tonic peripheral arousal. Given the malleability of SCL, if our findings are replicated, it warrants further exploration as a potential treatment target for ADHD

Objectives

Results

Conclusion