Tye Charlotte, Johnson Katherine A, Kelly Simon P, Asherson Philip, Kuntsi Jonna, Ashwood Karen L, Azadi Bahare, Bolton Patrick, McLoughlin Gráinne
King's College London, MRC Social Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, Psychology & Neuroscience, London, UK.
King's College London, Child & Adolescent Psychiatry, Institute of Psychiatry, Psychology & Neuroscience, London, UK.
J Child Psychol Psychiatry. 2016 Dec;57(12):1414-1423. doi: 10.1111/jcpp.12608. Epub 2016 Jul 28.
Attention deficit hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) show significant behavioural and genetic overlap. Both ADHD and ASD are characterised by poor performance on a range of cognitive tasks. In particular, increased response time variability (RTV) is a promising indicator of risk for both ADHD and ASD. However, it is not clear whether different indices of RTV and changes to RTV according to task conditions are able to discriminate between the two disorders.
Children with ASD (n = 19), ADHD (n = 18), ASD + ADHD (n = 29) and typically developing controls (TDC; n = 26) performed a four-choice RT task with slow-baseline and fast-incentive conditions. Performance was characterised by mean RT (MRT), standard deviation of RT (SD-RT), coefficient of variation (CV) and ex-Gaussian distribution measures of Mu, Sigma and Tau.
In the slow-baseline condition, categorical diagnoses and trait measures converged to indicate that children with ADHD-only and ASD + ADHD demonstrated increased MRT, SD-RT, CV and Tau compared to TDC and ASD-only. Importantly, greater improvement in MRT, SD-RT and Tau was demonstrated in ADHD and ASD + ADHD from slow-baseline to fast-incentive conditions compared to TDC and ASD-only.
Slower and more variable RTs are markers of ADHD compared to ASD and typically developing controls during slow and less rewarding conditions. Energetic factors and rewards improve task performance to a greater extent in children with ADHD compared to children with ASD. These findings suggest that RTV can be distinguished in ASD, ADHD and ASD + ADHD based on the indices of variability used and the conditions in which they are elicited. Further work identifying neural processes underlying increased RTV is warranted, in order to elucidate disorder-specific and disorder-convergent aetiological pathways.
注意力缺陷多动障碍（ADHD）和自闭症谱系障碍（ASD）在行为和基因方面存在显著重叠。ADHD和ASD的特征均为在一系列认知任务中表现不佳。特别是，反应时间变异性（RTV）增加是ADHD和ASD风险的一个有前景的指标。然而，尚不清楚RTV的不同指标以及根据任务条件RTV的变化是否能够区分这两种障碍。
患有ASD（n = 19）、ADHD（n = 18）、ASD + ADHD（n = 29）的儿童以及发育正常的对照组（TDC；n = 26）在具有慢基线和快速激励条件的四选反应时任务中进行测试。表现通过平均反应时（MRT）、反应时标准差（SD-RT）、变异系数（CV）以及Mu、Sigma和Tau的前高斯分布测量来表征。
在慢基线条件下，分类诊断和特质测量结果一致表明，与TDC和仅患有ASD的儿童相比，仅患有ADHD和患有ASD + ADHD的儿童表现出MRT、SD-RT、CV和Tau增加。重要的是，与TDC和仅患有ASD的儿童相比，ADHD和ASD + ADHD儿童从慢基线条件到快速激励条件下，MRT、SD-RT和Tau有更大改善。
在缓慢且回报较少的条件下，与ASD和发育正常的对照组相比，较慢且变异性更大的反应时是ADHD的标志。与患有ASD的儿童相比，精力因素和奖励在患有ADHD的儿童中能更大程度地改善任务表现。这些发现表明，基于所使用的变异性指标及其引发条件，RTV在ASD、ADHD和ASD + ADHD中是可区分的。有必要进一步开展工作，确定RTV增加背后的神经过程，以阐明特定于障碍和跨障碍趋同的病因途径。
