Diagnostic Differentiation of Major Depressive Episode and Persistent Depressive Disorder

Duration Criteria

Dysthymia (Persistent Depressive Disorder) requires depressive symptoms that persist for ≥ 2 years in adults (or ≥ 1 year in children/adolescents) and are less severe than those required for major depression【@1】.
A symptom duration of < 2 weeks does not meet criteria for either major depression or dysthymia; patients should be monitored for evolution of symptoms【@1】【@2】.
When symptoms last 2 weeks to 2 years and the full symptom count is met, the diagnosis is a major depressive episode【@1】.
Continuous symptoms for ≥ 2 years with severity below the major‑depression threshold suggest dysthymia【@1】.

A major depressive episode is diagnosed when ≥ 5 of the 9 DSM‑5 symptoms are present during the same 2‑week period, with at least one being depressed mood or markedly diminished interest/pleasure (anhedonia)【@1】【@2】.
The nine symptoms are: depressed mood, anhedonia, significant weight/appetite change, insomnia or hypersomnia, psychomotor agitation or retardation, fatigue, feelings of worthlessness or excessive guilt, diminished concentration, and recurrent thoughts of death【@1】.
< 5 symptoms persisting for ≥ 2 years meet criteria for dysthymia【@1】.
Prominent vegetative symptoms (sleep disturbance, appetite change, psychomotor changes, fatigue) and severe worthlessness or guilt favor a diagnosis of major depressive episode【@1】.
The presence of psychotic features, suicidal ideation with a concrete plan/intent, or severe psychomotor retardation indicates a major depressive episode even when the symptom count is borderline【@2】.

A major depressive episode must cause marked functional impairment in social, occupational, or other important areas【@1】.
Dysthymia typically produces less severe impairment on a day‑to‑day basis, though its chronic nature can lead to cumulative disability over time【@1】.

Step 1 – Assess Duration:
- < 2 weeks: No diagnosis; monitor.
- 2 weeks–2 years: If ≥ 5 symptoms with functional impairment → major depressive episode.
- ≥ 2 years: If symptom severity is below major‑depression threshold → dysthymia.【@1】
Step 2 – Count Symptoms & Assess Severity:
- ≥ 5 symptoms with marked impairment → major depressive episode, irrespective of chronicity.
- < 5 symptoms but persistent ≥ 2 years → dysthymia.【@1】
Step 3 – Evaluate Symptom Quality:
- Vegetative dominance → major depressive episode.
- Cognitive‑dominant (hopelessness, low self‑esteem, indecisiveness) with few vegetative signs → dysthymia.

Mild: 5–6 symptoms of mild intensity with minimal functional impairment【@2】.
Moderate: Symptom count and intensity between mild and severe【@2】.
Severe: All 9 symptoms present, or severe functional impairment, or presence of suicidal plan/intent, psychotic features, or marked psychomotor retardation【@2】.

In adolescents, irritable mood may substitute for depressed mood in both major depression and dysthymia【@2】.
Typical adolescent indicators include loss of interest in previously enjoyed activities, oppositional behavior, school refusal or poor performance, and talk of running away【@3】.

During normative grief, a diagnosis of major depression is withheld unless symptoms persist ≥ 1 month and at least one atypical grief symptom is present (e.g., extreme worthlessness unrelated to the loss, psychotic features, suicidal ideation, or psychomotor retardation)【@3】.
If symptoms continue > 2 months after the loss with functional impairment, full major‑depression criteria are applied【@3】.

Individuals with < 5 symptoms or symptom duration < 2 weeks do not meet criteria for major depression or dysthymia and are classified as having subsyndromal depression【@1】.
Subsyndromal depression carries a lower predictive value for future major depression compared with dysthymia, but recurrent brief episodes (< 2 weeks) warrant close monitoring【@1】.