Preliminary evidence of altered neural response during intertemporal choice of losses in adult attention-deficit hyperactivity disorder

Saori C Tanaka,Ayaka Ishii-Takahashi,Ayako Todokoro,Yukiko Kano,Yukika Nishimura,Noriaki Yahata,Yuki Kawakubo,Fumio Ohtake,Kiyoto Kasai

doi:10.1038/s41598-018-24944-5

Abstract

Impulsive behaviours are common symptoms of attention-deficit hyperactivity disorder (ADHD). Although previous studies have suggested functional models of impulsive behaviour, a full explanation of impulsivity in ADHD remains elusive. To investigate the detailed mechanisms behind impulsive behaviour in ADHD, we applied an economic intertemporal choice task involving gains and losses to adults with ADHD and healthy controls and measured brain activity by functional magnetic resonance imaging. In the intertemporal choice of future gains, we observed no behavioural or neural difference between the two groups. In the intertemporal choice of future losses, adults with ADHD exhibited higher discount rates than the control participants. Furthermore, a comparison of brain activity representing the sensitivity of future loss in the two groups revealed significantly lower activity in the striatum and higher activity in the amygdala in adults with ADHD than in controls. Our preliminary findings suggest that an altered size sensitivity to future loss is involved in apparent impulsive choice behaviour in adults with ADHD and shed light on the multifaceted impulsivity underlying ADHD.

Highlights

Attention-deficit hyperactivity disorder (ADHD) is characterized by inattention, impulsivity, and hyperactivity and affects 3.4% of children[1], with approximately 65% of children with attention-deficit hyperactivity disorder (ADHD) continuing to have some symptoms in adulthood[2]
Given these previous findings on brain function, we hypothesized that the brain areas receiving projections from dopaminergic neurons, as well as the frontal areas that have connections to the striatum, are involved in the delay discounting of gains and losses and that the brain activity associated with size sensitivity in these areas shows a difference in loss prediction between ADHD and healthy individuals
Fifteen adults with ADHD and 19 normal control (NC) participants performed repeated intertemporal choice tasks[10] for future gains (GAIN condition) and losses (LOSS condition) (Fig. 1; see Methods), selecting either a white or yellow square corresponding to a smaller (+10/−10 yen) or larger (+40/−40 yen) reward/punishment option, respectively

Summary

Introduction

Attention-deficit hyperactivity disorder (ADHD) is characterized by inattention, impulsivity, and hyperactivity and affects 3.4% of children[1], with approximately 65% of children with ADHD continuing to have some symptoms in adulthood[2]. A clinical study found that children with ADHD are prone to drug, alcohol, and gambling addictions as adults[36] Another model of impulsive choice in ADHD that does take into account the specific features of both gains and losses[37,38] proposes that individuals with ADHD cannot resist the temptation of immediate gains because of a reduced sensitivity to future negative outcomes caused by choosing immediate gains. ADHD has traditionally been considered a disorder of childhood and impulsive choice has been reported in children and adolescents with ADHD42, adults diagnosed as having ADHD in childhood report difficulties in social and economic activities, such as higher school dropout rates, underemployment, compromised job performance, difficulty maintaining employment, and problems maintaining friendships[43]

Methods

Results

Conclusion