Persistent Depressive Disorder Duration
Persistent depressive disorder requires depressive symptoms present on most days for at least 2 years in adults. 1, 2
Diagnostic Duration Criteria
The minimum duration is 2 years of depressive symptoms on most days to meet diagnostic criteria for persistent depressive disorder (PDD), which distinguishes it from major depressive disorder that requires only 2 weeks of symptoms 1, 2
During this 2-year period, the patient must NOT meet full criteria for major depressive disorder - this is a critical distinction that separates PDD from chronic major depression 2
The American College of Physicians defines dysthymia (now subsumed under PDD in DSM-5) as a chronic depressive disorder characterized by depressed mood on most days for at least 2 years 1
Clinical Course Characteristics
PDD represents a persistent, chronic ailment rather than an episodic disorder, contrasting with major depressive disorder which presents as discrete episodes with interepisode remissions 2
The disorder encompasses several chronic presentations including dysthymia with or without superimposed major depressive episodes, chronic major depression, and recurrent major depression without recovery between episodes 3
Key Assessment Points
Direct patient and family interviews must specifically assess symptom onset, duration, and functional impairment patterns across various settings to accurately determine the 2-year chronicity requirement 2
Collateral information from family members or other observers about the longitudinal course of symptoms is essential to avoid misclassifying PDD as episodic major depressive disorder 2
Common Diagnostic Pitfalls
Failing to adequately assess the full 2-year duration leads to misclassification of PDD as episodic MDD, which has significant treatment implications given the different therapeutic approaches required 2
Clinicians must be vigilant about gathering thorough longitudinal history, as PDD can be difficult to detect in psychiatric and primary care settings until it intensifies with a superimposed major depressive episode 4, 3