What are the primary symptoms and treatment options for a major depressive episode?

Psychiatric Symptomatology in Major Depressive Episode

A major depressive episode requires at least five symptoms present during a 2-week period, with at least one being either depressed mood or anhedonia (loss of interest/pleasure), plus four additional symptoms from the following: significant weight/appetite changes, sleep disturbance, psychomotor agitation or retardation, fatigue, worthlessness/guilt, concentration difficulties, or recurrent thoughts of death/suicidal ideation. 1, 2

Core Diagnostic Criteria

The American Psychiatric Association defines MDD as requiring symptoms that last at least 2 weeks and cause significant functional impairment in daily activities 1, 2. The two cardinal symptoms are:

• Depressed mood - A prominent and relatively persistent depressed or dysphoric mood that interferes with daily functioning nearly every day 1, 3
• Anhedonia - Loss of interest or pleasure in nearly all activities that were previously enjoyable 1, 4

At least one of these two core symptoms must be present for diagnosis 1, 2.

Associated Symptoms (Require 4 of the Following 8)

Neurovegetative Symptoms

• Appetite/weight changes - Significant weight loss when not dieting, weight gain, or marked changes in appetite 1, 3
• Sleep disturbance - Insomnia or hypersomnia occurring nearly every day 1, 3
• Psychomotor changes - Observable agitation or retardation nearly every day (not merely subjective feelings) 1, 3
• Fatigue - Loss of energy or increased fatigue nearly every day 1, 3

Cognitive and Affective Symptoms

• Worthlessness/guilt - Feelings of worthlessness or excessive/inappropriate guilt (may be delusional) 1, 3
• Concentration difficulties - Diminished ability to think or concentrate, or marked indecisiveness nearly every day 1, 3
• Suicidal ideation - Recurrent thoughts of death (not just fear of dying), recurrent suicidal ideation without a specific plan, or a suicide attempt or specific plan for committing suicide 1, 3

Severity Classification

Depression severity is determined by symptom count, intensity of symptoms, and degree of functional impairment 2:

• Mild depression - Fewer symptoms, minimal functional impairment 2
• Moderate depression - Intermediate symptom burden and functional impairment 2
• Severe depression - High symptom count, severe intensity, marked functional impairment, or presence of high-risk features (active suicidality, psychotic features) 2

Assessment Tools for Symptom Measurement

• Patient Health Questionnaire-9 (PHQ-9) - Validated screening tool with cutoff ≥8 indicating clinically significant depression requiring treatment 1, 2, 5
• Hamilton Depression Rating Scale (HAM-D) - Clinician-administered scale where score ≤7 typically indicates remission 1, 2
• Montgomery-Åsberg Depression Rating Scale (MADRS) - Recommended for assessing depression severity 2

Treatment response is typically defined as ≥50% reduction in measured severity using these validated tools 1, 2.

Critical Diagnostic Pitfalls to Avoid

• Failing to assess functional impairment - Symptoms must cause clinically significant distress or impairment in social, occupational, or other important areas of functioning 1
• Missing suicidality assessment - Always evaluate for suicidal ideation, intent, and plan, especially during initial assessment and early treatment 2
• Overlooking medical causes - Rule out mood disorder due to another medical condition or substance/medication-induced depressive disorder before diagnosing primary MDD 6
• Inadequate duration assessment - Symptoms must persist for at least 2 weeks; transient sadness or grief reactions do not meet criteria 1, 2

Treatment Implications Based on Symptom Profile

For mild depression with prominent anhedonia, initiate cognitive behavioral therapy (CBT) with behavioral activation as first-line treatment 5. For moderate to severe depression, either CBT or second-generation antidepressants (SSRIs/SNRIs) are equally effective first-line options 1, 2. The American College of Physicians strongly recommends selecting between these two options after discussing treatment effects, adverse effects, cost, accessibility, and patient preferences 1.

Treatment should continue for 4-9 months after satisfactory response for first episodes, and ≥1 year for recurrent episodes to prevent relapse 2, 3.