Irritable Kids – Nuisance or Sign of Future Mental Illness?

By Cristina Mestre

As many parents know, children of all ages can be irritable at times.  Yet while some irritability in children is normal, very high levels of irritability (or even very low levels) may put kids at risk for mental illness. While we know that children with behavioral problems are at risk for mental illness later in life, we don’t know why irritability in particular puts kids at risk.

Susan Perlman, Ph.D., a cognitive neuroscientist at the University of Pittsburgh School of Medicine, is researching irritability in young kids (ages 3-6) in order to determine if these children will be “just fine” or if their irritability levels will predict future behavioral and psychological issues.  I.e., she wants to know, “why do some irritable kids end up with mental illness, and others just become irritable but normally functioning adults?”

Dr. Perlman’s work involves imaging the brains of children with varying levels of irritability while they perform tasks that generally provoke intense emotional reactions, in order to determine if neuroimaging can predict which children will develop normally and which children are on a trajectory towards psychopathology.  The technique she uses to image the brains of young children is called near-infrared spectroscopy (fNIRS).

The way this is done is by having kids wear what looks like a headband or swim cap– this device sends light into the brain while kids perform certain tasks on a computer.  It’s as safe as spending 20 minutes outside on a sunny day and measures bloodflow, similar to the measurement of a functional MRI, but it’s less sensitive to movement.  Plus, it is easy for the kids to use and fun, given that the kids play computer games, or interact with parents or a member of the research team, while wearing the device.

In a study published online this week in the journal NeuroImage, Dr. Perlman found that in a sample of children from community (kids not presenting with psychiatric problems), an area of the brain called the lateral prefrontal cortex is active during frustration. But, most importantly, the more parents reported high levels of irritability in their child, the more they used this region of the brain, which is associated with emotional control, when frustrated.

“We expected the opposite,” noted Dr. Perlman.  “We thought kids who were irritable wouldn’t be using the part of the brain that controls emotion. But our findings suggest kids with active lateral prefrontal cortexes may be less likely to develop mental illness because that area of the brain is working well.  In children diagnosed with psychiatric disorders, we expect dysfunction of this area during frustration.”

By characterizing the biological mechanisms underlying the wide range of irritability observed in early childhood, Dr. Perlman and colleagues hope to discover dysfunctional brain circuitry in irritable preschoolers which might predispose some irritable children towards a trajectory of mental illness as they enter the critical school years.  Her current studies use similar methodology to explore neural mechanisms for irritability in clinical samples across childhood.