What is the recommended treatment for a 19-year-old female patient with moderate to severe depression, as indicated by a Patient Health Questionnaire-9 (PHQ-9) score of 16, Generalized Anxiety Disorder (GAD) mood swings, and recent agitation, who does not smoke or consume alcohol?

Treatment Recommendation for 19-Year-Old with Moderate-Severe Depression and Anxiety

This patient requires immediate referral to psychology and/or psychiatry for formal diagnosis and high-intensity treatment, combined with either cognitive behavioral therapy or a second-generation antidepressant (SSRI), with close monitoring for suicidality given her age and symptom severity. 1, 2, 3

Severity Assessment and Risk Stratification

Your patient's PHQ-9 score of 16 places her in the moderate to severe depression category (15-19 range), indicating that most depressive symptoms are present and interfering moderately to markedly with functioning. 2, 3, 4 This severity level mandates professional mental health intervention, not watchful waiting or low-intensity approaches. 1, 3

Critical Safety Assessment Required

• Immediately assess PHQ-9 item 9 regarding self-harm thoughts - if any frequency is endorsed, emergency psychiatric evaluation is required regardless of total score. 1, 2, 4
• Evaluate for additional red flags: severe agitation (which she has), psychosis, confusion, or risk of harm to others. 1, 4
• Given her age (19 years), she falls into the highest-risk category for antidepressant-induced suicidality (ages 18-24), requiring enhanced monitoring if pharmacotherapy is initiated. 5

Recommended Treatment Algorithm

Step 1: Immediate Mental Health Referral (Mandatory)

Refer to psychology and/or psychiatry within 1-2 weeks for formal diagnostic assessment and treatment planning. 1, 3, 4 At this severity level (PHQ-9 ≥15), high-intensity interventions delivered by licensed mental health professionals are required. 1, 3

Step 2: Choose Initial Treatment Modality

Select between cognitive behavioral therapy (CBT) OR a second-generation antidepressant (SSRI) as first-line treatment after discussing treatment effects, adverse effects, cost, accessibility, and patient preference. 1 Both have equivalent efficacy for moderate-severe depression. 1

Option A: Cognitive Behavioral Therapy (Preferred if accessible)

• Individual CBT delivered by licensed mental health professional using treatment manuals that include cognitive change, behavioral activation, biobehavioral strategies, education, and relaxation techniques. 1, 3
• CBT is particularly appropriate given her comorbid GAD symptoms and mood swings, as it addresses both anxiety and depression. 6
• Requires weekly sessions initially with a trained therapist. 1

Option B: Second-Generation Antidepressant (If CBT unavailable or patient preference)

• SSRIs are first-line pharmacotherapy for both depression and comorbid GAD, making them ideal for this patient's presentation. 6, 7
• Common starting options: fluoxetine 20mg daily, sertraline 50mg daily, or escitalopram 10mg daily. 1
• Critical warning for this 19-year-old patient: Antidepressants increase risk of suicidal thinking and behavior in patients ages 18-24 during early treatment phases. 5

Step 3: Enhanced Monitoring Protocol (Essential for Age 18-24)

Weekly contact for the first 4 weeks, then biweekly for 8 weeks to monitor for: 5

• Clinical worsening or emergence of suicidality
• Anxiety, agitation, panic attacks, insomnia, irritability, hostility, aggressiveness, impulsivity, akathisia, hypomania, or mania 5
• These symptoms may represent precursors to emerging suicidality 5

Reassess PHQ-9 at each contact - a clinically meaningful improvement is ≥5 points reduction. 8 If no improvement after 6-8 weeks, consider switching or augmenting treatment. 8

Step 4: Address Comorbid GAD

Her GAD symptoms with mood swings require specific attention:

• GAD-7 screening should be completed to quantify anxiety severity (scores ≥10 indicate moderate-severe anxiety requiring treatment). 4, 9
• SSRIs treat both depression and GAD simultaneously, making them efficient for comorbid presentations. 6, 7
• If using CBT alone, ensure the protocol specifically addresses worry and anxiety symptoms, not just depression. 6

Common Pitfalls to Avoid

• Never omit the self-harm assessment (PHQ-9 item 9) - this artificially lowers scores and misses critical risk information. 2
• Do not underestimate PHQ-9 score of 16 - this represents significant clinical depression requiring professional intervention, not self-help or watchful waiting. 3
• Do not prescribe antidepressants without establishing close follow-up - the first 4-8 weeks carry highest risk for treatment-emergent suicidality in young adults. 5
• Do not fail to screen for bipolar disorder before initiating antidepressants - mood swings and agitation could represent bipolar disorder, where antidepressant monotherapy may precipitate mania. 1
• Do not treat depression alone while ignoring GAD - comorbid anxiety-depression causes greater disability than either condition alone and requires integrated treatment. 7

Special Considerations for This Patient

• Her "mood swings" and agitation warrant careful evaluation for bipolar disorder before starting antidepressants. 1
• GAD is highly prevalent in women over age 35 (10%), but also occurs in younger adults and frequently comorbid with depression. 7
• Her non-smoking, non-alcohol use is protective and eliminates substance-induced mood concerns. 1
• The chronic, waxing-waning course typical of GAD suggests she may need long-term treatment rather than acute intervention only. 7

Documentation and Family Involvement

Educate the patient and involve family/caregivers (with patient consent) to monitor for emergence of agitation, irritability, unusual behavior changes, and suicidality, with instructions to report immediately. 5 Prescribe the smallest quantity of medication consistent with good management to reduce overdose risk. 5