A patient shows a pattern of quick, disproportionate anger. Before revealing the answer, decide what distinguishes impulsive personality disorder from irritability.

Ask whether this is a lifelong personality pattern of explosive, poorly controlled action, or a sustained but potentially episodic lowering of the threshold for annoyance. Impulsive personality disorder differs from ordinary irritability or bad temper in the explosive, disproportionate, and poorly controlled nature of the outbursts, together with the characteristic build-up and remorse some people describe, and it is a longstanding trait pattern present since adolescence. Irritability, considered as a morbid disorder of emotion, is a sustained, pathological lowering of the threshold for annoyance or anger that can accompany either a low or an elevated mood state, and need not involve dramatic, explosive action or a build-up-and-remorse cycle, nor need it be a lifelong personality trait. Whether the pattern is a lifelong, explosive-action personality trait or a mood-linked lowering of the annoyance threshold is the key distinguishing feature.