Irritability in boys with autism spectrum disorders: an investigation of physiological reactivity

Abstract

BackgroundIrritability in people with autism spectrum disorders (ASD) is common and impairing, yet its mechanisms remain understudied. We investigated symptom reporting and mechanisms of irritability in ASD, focusing on the relation between irritability and physiological stress responses.MethodsForty‐seven unmedicated boys with high‐functioning ASD (hfASD) and 23 typically developing boys aged 10–16 years completed a psychosocial stress test. Changes in cortisol, heart rate and heart rate variability throughout the test were recorded. Self‐ and parent‐reported measures of irritability were obtained. Irritability symptom reporting in the hfASD group was compared to two groups of boys without ASD: highly irritable boys (severe mood dysregulation, SMD; n = 40) and healthy‐control boys (HC; n = 30).ResultsBoys with hfASD scored significantly higher on irritability than HC boys, and they reported a pattern of irritability symptoms closely resembling that of boys with SMD. The internal consistency of irritability in hfASD was high by parent‐ and self‐report. Although boys with hfASD showed significant stress‐induced changes in cortisol and heart rate, those who rated themselves as highly irritable had lower cortisol levels throughout the test compared to those low on irritability. Participants rated as highly irritable by their parents showed blunted cortisol and heart rate responses to stress. The effects of irritability on heart rate, but not cortisol, were accounted for by trait anxiety.ConclusionsIrritability can be measured reliably in hfASD and is associated with distinct biological responses to stress.

Physiological Response to Social Evaluative Threat in Adolescents with Autism Spectrum Disorder

“…Importantly, these studies employed adapted versions of the TSST that ostensibly tax visual attention and memory, and do not use a social peer. Despite these differences from the current protocol, the findings outlined above of blunted ANS measures in ASD are in agreement with the findings in the present study (Levine et al 2012; Hollocks et al 2014; Mikita et al 2015). …”

“…The authors did not find significant differences in HRV between TD and ASD groups, but there was a non-significant overall reduction in RSA in the ASD group at baseline and during all portions of the TSST-C, which parallels the present findings of reduced RSA. Another study used a stress test similar to the TSST, but, instead of a serial subtraction task, asked participants to complete the Rey–Osterrieth Complex Figure task (Mikita et al 2015). This study measured heart rate as a proxy for stress reactivity to the task, but did not measure HRV or PNS function per se.…”

“…This study measured heart rate as a proxy for stress reactivity to the task, but did not measure HRV or PNS function per se. The authors reported reduced heart rate to the stressor in children with ASD with co-occurring high anxiety compared to children with ASD and low anxiety, which they interpret as “stress induced physiological withdrawal” (Mikita et al 2015, p. 1124). Finally, Hollocks et al (2014) employed a variant of the TSST in a mixed sample of ASD children and adolescents with and without comorbid anxiety disorders.…”

“…In child and adult populations without neurodevelopmental disorders, the TSST has demonstrated reliable increases in the stress response using both neuroendocrine (for review, see Foley and Kirschbaum 2010) and psychophysiological markers of stress responsivity (for review, see Allen et al 2014). When the TSST has been implemented in neural-cardiac studies of children with ASD, findings have been mixed; two studies have reported reduced responsivity in ASD (Mikita et al 2015; Hollocks et al 2014) and one study found no differences (Levine et al 2012) from TD controls. This inconsistency in findings is likely due to methodological differences in study design, including differences in the type of physiological marker measured, as some studies have focused on group differences in RSA, and others on within-group heart rate changes between baseline and the task.…”

Longitudinal Study of High and Low Functioning Preschool Children with ASD and the Progress Made Following Therapeutic Intervention

“…In a study of 101 children (Salazar et al, 2015) aged 4.5-9.8 years with ASD, 90.5% of the sample presented with the following disorders: anxiety disorder, phobias, depression, ADHD, oppositional disorder and conduct disorder. A number of studies with older children and adolescents with ASD showed also high levels of psychiatric problems, e.g., depression and irritability (Joshi et al, 2014;Andersen et al, 2015;Mikita et al, 2015), as well as ADHD (Levy et al, 2010). Do these co-occurring difficulties exist in very young preschool children?…”