Editorial: Mood Instability: What It Is, Why It Matters, and What to Do About It.

Mood instability, defined as frequent, sudden, and unpredictable alterations in irritability, elation/activation, and anxiety/depression, is associated with psychopathology in youth and adults. While transdiagnostic, mood instability has unique associations with bipolar disorder (BD) and can occur inter-episodically. Mood instability is a risk for BD type 1 or type 2 in high-risk individuals.