Symptoms of ADHD in Children with High-Functioning Autism Are Related to Impaired Verbal Working Memory and Verbal Delayed Recall

Per Normann Andersen,Kjell Tore Hovik,Jens Egeland,Merete Øie,Erik Winther Skogli,Bart Rypma

doi:10.1371/journal.pone.0064842

Per Normann Andersen, Kjell Tore Hovik + Show 4 more

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https://doi.org/10.1371/journal.pone.0064842

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Abstract

Symptoms similar to those found in Attention-Deficit/Hyperactivity Disorder (ADHD) often occur in children with Autism Spectrum Disorders (ASD). The objective of the current study was to compare verbal working memory, acquisition and delayed recall in children with High-Functioning Autism (HFA) to children with ADHD and typically developing children (TDC). Thirty-eight children with HFA, 79 with ADHD and 50 TDC (age 8–17) were assessed with a letter/number sequencing task and a verbal list-learning task. To investigate the possible influence of attention problems in children with HFA, we divided the HFA group into children with (HFA+) or without (HFA−) “attention problems” according to the Child Behaviour Checklist 6–18. The children with HFA+ displayed significant impairment compared to TDC on all three neurocognitive measures, while the children with HFA− were significantly impaired compared to TDC only on the working memory and acquisition measures. In addition, the HFA+ group scored significantly below the HFA− group and the ADHD group on the verbal working memory and delayed recall measures. The results support the proposition that children with HFA+, HFA−, and ADHD differ not only on a clinical level but also on a neurocognitive level which may have implications for treatment.

Highlights

The main manifestations of Autism Spectrum Disorders (ASD) are impaired social interaction, communication, and restricted and repetitive patterns of behaviours, interests and activities [1]
There were no significant differences between the High-Functioning Autism (HFA) and Attention-Deficit/Hyperactivity Disorder (ADHD) groups
When comparing the HFA and typically developing children (TDC) groups, the main effect of diagnosis when controlling for full-scale IQ (FSIQ) were as follows: verbal working memory (LNS) (F (1, 85) = 30.2, p,.001), Hopkins Verbal Learning Test Revised (HVLT-R) acquisition (F (1, 85) = 13.5, p,.001), and HVLT-R delayed recall (F (1, 85) = 7.5, p = .007)

Summary

Introduction

The main manifestations of Autism Spectrum Disorders (ASD) (i.e., autistic disorder, Asperger’s syndrome and pervasive developmental disorder – not otherwise specified) are impaired social interaction, communication, and restricted and repetitive patterns of behaviours, interests and activities [1]. Comorbidity between ASD and ADHD has been reported to be within the range of 14–78% [4,5,8,9,10,11,12]. Psychopathological, neurocognitive, brain imaging and genetic studies suggest possible pathophysiological links between ASD and ADHD [13,14,15,16]. Research has shown different patterns of deficits in executive functioning in children with ASD and ADHD [13]. Children with ASD typically have difficulties with planning and cognitive flexibility, while children with ADHD more commonly struggle with inhibition and sustained attention [13]. Children with ASD and ADHD-like symptoms seem to display deficits in inhibition similar to that found in children with ADHD [17,18]

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