Irritability, Negative Life Events and the Course of Anxiety and Depressive Symptoms in a Clinical Sample of Youth: A Longitudinal Study.

Objective: Irritability, the tendency to react with anger, and the experience of negative life events (NLE) have independently been associated with the emergence of anxiety and depression. Here, we investigate how irritability and cumulative effects of NLE interactively predict the course of anxiety and depression in the context of common psychiatric disorders. Method: 432 youth with no psychiatric diagnosis, or a diagnosis of an anxiety disorder, Attention-Deficit/ Hyperactivity Disorder (ADHD), or Disruptive Mood Dysregulation Disorder (DMDD), participated in this study. At baseline, we assessed NLE, parent and youth reports of irritability and anxiety, and youth reports of depression. Symptoms were annually reassessed for up to four years. Results: In youth without psychiatric diagnoses but with elevated baseline irritability, the presence of NLE predicted decreasing anxiety, while the absence of NLE predicted increasing anxiety. In youth with an anxiety disorder, elevated baseline irritability predicted decreasing anxiety independent of NLE, while a large cumulative effect of NLE predicted increasing depression. NLE predicted persisting mild anxiety in ADHD and persisting mild depressive symptoms in DMDD. Conclusion: Our findings suggest that, particularly in non-referred samples, NLE might moderate the relationship between irritability and future anxiety such that irritability/ anger in the context of NLE can positively affect the course of anxiety. Future work replicating this finding while repeatedly measuring NLE and rigorously controlling for potentially confounding effects of treatment, is warranted.