What is the likely diagnosis and treatment for a 24-year-old female medical student with loss of interest in daily activities, constant low mood, low self-esteem, and difficulty maintaining friendships and social interactions?

Major Depressive Disorder

This 24-year-old medical student meets diagnostic criteria for Major Depressive Disorder (MDD) and should be started on combination treatment with an SSRI (sertraline 50mg daily or fluoxetine 20mg daily) plus cognitive-behavioral therapy, after ruling out suicidal ideation and medical causes. 1, 2, 3, 4

Diagnostic Assessment

Confirm the diagnosis by establishing that she has at least 5 of the following symptoms present for at least 2 weeks, with at least one being depressed mood or loss of interest: 5, 1, 6

• Depressed mood most of the day, nearly every day (she has constant low mood) 5
• Markedly diminished interest or pleasure in activities (she has loss of interest in daily activities) 5
• Low self-esteem/feelings of worthlessness (she has very low self-esteem) 5
• Difficulty maintaining social relationships (she cannot maintain friendships) 5
• Impaired concentration affecting academic performance (affecting her studies) 5

This patient's age and presentation are epidemiologically typical—MDD peaks in late adolescence and early adulthood, and the American Academy of Pediatrics recommends depression screening for all individuals ages 11-21 years. 1

Critical Safety Assessment

Before proceeding with any treatment plan, you must directly ask about suicidal ideation using specific language: 5, 2

• Ask: "Have you ever wished you were dead?" 5
• Follow immediately with: "Have you ever done anything on purpose to hurt or kill yourself?" 5
• If positive responses, ask: "If you were to kill yourself, how would you do it?" and assess for firearms in the home 5
• If any risk of self-harm is identified, immediately refer for emergency psychiatric evaluation, facilitate one-to-one observation, and implement harm-reduction interventions—safety takes precedence over confidentiality. 2

Rule Out Medical Causes First

Before attributing symptoms to MDD, exclude the following medical conditions that can mimic depression: 5, 2

• Hypothyroidism (check TSH) 5, 2
• Anemia or vitamin deficiencies 2
• Medication side effects 2
• Substance abuse 5
• Delirium from infection or electrolyte imbalance 5, 2

Treatment Algorithm

First-Line Pharmacotherapy

Start with an SSRI as first-line medication: 3, 4

• Sertraline 50mg daily (FDA-approved for MDD in adults, can titrate up to 200mg daily) 3
• Alternative: Fluoxetine 20mg daily (FDA-approved for MDD in adults and adolescents, established efficacy in 5-6 week trials) 4

The goal is complete remission—all symptoms must be treated until undetectable, not just improvement in mood. 7, 8

Concurrent Psychotherapy

Initiate cognitive-behavioral therapy (CBT) or psychoeducational therapy delivered by appropriately trained individuals alongside medication. 5

• CBT targets cognitive distortions that accompany depression, particularly hopelessness 5
• Psychotherapy addresses inappropriate coping styles like catastrophizing 5

Monitoring and Follow-Up

Assess treatment response at 6-8 weeks using validated instruments: 5

• PHQ-9 (Patient Health Questionnaire-9): 9-item self-report scale assessing DSM-IV criteria for MDD 5
• BDI (Beck Depression Inventory): Scores ≥20 suggest clinical depression 5
• HAM-D (Hamilton Rating Scale for Depression): Score 7-17 = mild, 18-24 = moderate, ≥25 = severe depression 5

Document functional impairment in work (studies), relationships (friendships), and daily activities—this is essential for tracking treatment response. 2

If Inadequate Response After 6-8 Weeks

For patients who do not achieve remission after adequate treatment trials: 7

1. Evaluate adherence to medication 7
2. Screen for comorbid psychiatric disorders (anxiety, substance abuse) 5, 7
3. Consider switching to a different SSRI or SNRI 7
4. Consider augmentation strategies (add bupropion, mirtazapine, or atypical antipsychotic) 7
5. Refer to psychiatry if treatment-resistant 7

Common Pitfalls to Avoid

Do not dismiss irritability as "just stress"—in young adults, MDD frequently presents with irritability rather than classic depressed mood. 5, 1

Do not rely solely on symptom counts without assessing functional impairment and duration—she has 6 months of symptoms affecting her studies and relationships, which confirms clinical significance. 2

Never omit the suicidal ideation assessment, even if the patient appears low-risk—this artificially lowers risk detection and misses critical safety information. 2

Do not attribute all symptoms to academic stress without formal evaluation—medical students are at high risk for MDD and require the same diagnostic rigor as any other patient. 1

Recognize that residual symptoms (particularly sleep disturbance, fatigue, and cognitive dysfunction) often persist despite mood improvement and require continued treatment adjustment. 7, 8