Neurophysiological Markers of Pediatric Irritability and Its Response to Intervention

There has been an increasing focus on the adverse impacts of irritability, defined as increased tendency towards anger. Irritability worsens peer relationships, family functioning, academic performance and is a risk factor for depression, suicide and substance use and is one of the main reasons why children get referred for treatment. It has been identified as transdiagnostic entity meriting investigation as a treatment target for personalized intervention given its prevalence and morbidity. Most children with prominent irritability also meet criteria for Attention Deficit Hyperactivity Disorder (ADHD) but only a subset of children with ADHD manifest impairing levels of irritability. Irritability levels are only minimally correlated with severity of ADHD symptoms suggesting that irritability is not simply a manifestation of severe ADHD. The first line treatment for irritability in children with ADHD is to optimize the dose of the CNS stimulant. However, there is great heterogeneity in response, with baseline mood lability being the best marker for both improving and worsening irritability. In addition, increased irritability is one of the most common reasons why parents stop these medications. The unpredictability in response to CNS stimulants has led to the increasing use of antipsychotics and other non-evidence based treatments for ADHD. It is unknown what drives this heterogeneity in response in part because little is known about the underlying causal mechanisms for irritability in youth with ADHD. Two areas theorized to contribute to irritability include impairments in learning from experience (instrumental learning) and sensitivity to reward and loss.1 There are objective methods for measuring these domains in children through the use of even-related potentials (ERPs)- synchronous neural activity in response to a stimulus. Reward positivity (RewP) is an ERP component occurring in response to feedback on task performance that can be broken down to separate rewar