van Belle Janna, van Hulst Branko M, Durston Sarah
NICHE Lab, Department of Psychiatry, Rudolf Magnus Magnus Brain Centre, University Medical Centre Utrecht, Utrecht, The Netherlands.
J Child Psychol Psychiatry. 2015 Dec;56(12):1316-26. doi: 10.1111/jcpp.12417. Epub 2015 Apr 13.
Intra-individual variability reflects temporal variation within an individual's performance on a cognitive task. Children with developmental disorders, such as ADHD and ASD show increased levels of intra-individual variability. In typical development, intra-individual variability decreases sharply between the ages 6 and 20. The tight link between intra-individual variability and age has led to the suggestion that it may be marker of neural development. As there is accumulating evidence that ADHD and ASD are characterised by atypical neurodevelopmental trajectories, we set out to explore developmental changes in intra-individual variability in subjects with ADHD and ASD.
We used propensity score matching to match a cross-sectional sample of children with ADHD, ASD and control subjects (N = 405, aged 6-19 years old) for age, IQ and gender. We used ex-Gaussian distribution parameters to characterise intra-individual variability on fast responses (sigma) and slow responses (tau).
Results showed that there was a similar decrease in mean response times with age across groups, and an interaction between age and group for measures of variability, where there was a much lower rate of change in the variability parameters (sigma and tau) for subjects with ASD compared with the other two groups. Subjects with ADHD had higher intra-individual variability, reflected by both sigma and tau, but the rate of decrease in variability with age was similar to that of the controls.
These results suggest that subjects with ADHD, ASD and controls differ in the rate at which intra-individual variability decreases during development, and support the idea that intra-individual variability may be a marker of neural development, mimicking the neurodevelopmental changes in these disorders.
个体内变异性反映了个体在认知任务表现中的时间变化。患有发育障碍的儿童，如注意力缺陷多动障碍（ADHD）和自闭症谱系障碍（ASD），其个体内变异性水平会升高。在典型发育过程中，个体内变异性在6至20岁之间会急剧下降。个体内变异性与年龄之间的紧密联系表明，它可能是神经发育的一个标志。由于越来越多的证据表明ADHD和ASD具有非典型的神经发育轨迹，我们着手探索ADHD和ASD患者个体内变异性的发育变化。
我们使用倾向得分匹配法，为年龄、智商和性别的ADHD儿童、ASD儿童和对照组儿童（N = 405，年龄6 - 19岁）的横断面样本进行匹配。我们使用前高斯分布参数来表征快速反应（sigma）和慢速反应（tau）的个体内变异性。
结果显示，各年龄组的平均反应时间随年龄增长而有类似的下降，并且在变异性测量方面年龄与组别之间存在交互作用，其中与其他两组相比，ASD患者变异性参数（sigma和tau）的变化率要低得多。ADHD患者的个体内变异性更高，这通过sigma和tau两者都能体现出来，但变异性随年龄下降的速率与对照组相似。
这些结果表明，ADHD、ASD患者和对照组在发育过程中个体内变异性下降的速率存在差异，并支持个体内变异性可能是神经发育标志的观点，这与这些疾病中的神经发育变化相类似。
