What is a primary characteristic of persistent depressive disorder?

Persistent depressive disorder, also known as dysthymia, is characterized by a chronic state of depression that lasts for a significant period of time, specifically for at least two years in adults and one year in children and adolescents. A central feature of this condition is the absence of symptom-free intervals during this duration. This means individuals experience ongoing depressive symptoms without returning to a normal mood for longer than two months during the two-year period.

This distinguishes persistent depressive disorder from other types of depressive disorders, where symptoms can be more transient or episodic. The other options suggest short-lived or episodic symptoms, which do not align with the nature of persistent depressive disorder.