Treatment-Resistant Depression

Treatment-Resistant Depression

Treatment-Resistant Depression

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Definition & Diagnosis - Spotting Stubborn Sadness

  • Treatment-Resistant Depression (TRD): Defined as Major Depressive Disorder (MDD) that fails to achieve satisfactory improvement despite ≥2 adequate trials of different antidepressant medications.
    • "Adequate trial": Sufficient dose (optimal range) for sufficient duration (typically 6-8 weeks).
    • Antidepressants should ideally be from different pharmacological classes, or include an augmentation strategy.
  • Critical Diagnostic Steps:
    • Confirm the primary diagnosis of MDD (using DSM-5 or ICD-11 criteria).
    • Thoroughly rule out pseudo-resistance:
      • Inadequate antidepressant dose or duration.
      • Poor patient adherence to treatment.
      • Presence of unaddressed comorbid medical conditions (e.g., hypothyroidism, anemia) or psychiatric conditions (e.g., anxiety disorders, substance use).
      • Misdiagnosis (e.g., Bipolar depression, personality disorder).
    • Assess overall illness severity and functional impairment.

⭐ Approximately 30-40% of individuals with MDD may not respond adequately to initial standard antidepressant treatments, potentially meeting criteria for TRD.

Evaluation & Workup - Digging Deeper Doc

  • 1. Confirm MDD & Severity:
    • Exclude Bipolar Disorder (e.g., MDQ).
    • Standardized scales (e.g., HAM-D, MADRS).
  • 2. Review Treatment History (📌 "2 D's & A"):
    • Duration: ≥ 6-8 weeks per trial.
    • Different Classes: ≥ 2 failed adequate trials.
    • Adherence & Adequate Dose.
  • 3. Screen for Confounders:
    • Medical: CBC, TSH, Vit B12/D.
    • Substance use.
    • Comorbid psychiatric conditions (anxiety, personality disorders).
  • 4. Psychosocial Assessment:
    • Stressors, social support.

⭐ A key criterion for TRD is failure to respond to at least two different antidepressant trials of adequate dose and duration (typically 6-8 weeks each).

Pharmacological Strategies - Pill Power-Ups

  • Optimization: Optimize current AD: Maximize dose & ensure adequate trial duration (4-6 weeks).
  • Switching: Switch AD: To another agent, intra-class or different class (e.g., SSRI to SNRI/TCA).
  • Augmentation Strategies:
    • Lithium: Target 0.6-1.2 mEq/L.
    • AAPs: e.g., Aripiprazole, Quetiapine XR, Olanzapine, Risperidone.
    • Thyroid Hormone (T3 - Liothyronine): 25-50 mcg/day.
    • Buspirone.
  • Combination Therapy: Combine ADs: Different mechanisms (e.g., SSRI + Mirtazapine/Bupropion). ⚠️ Serotonin Syndrome.
  • Novel Rapid-Acting Agents: Esketamine (intranasal)/Ketamine (IV): Rapid-acting agents for severe TRD or acute suicidal ideation.
  • MAOIs (e.g., Phenelzine, Tranylcypromine): Potent, but last-line. Strict dietary (tyramine) & drug interaction precautions. ⚠️ Hypertensive Crisis.

⭐ Lithium augmentation is a gold-standard TRD strategy; response often in 2-4 weeks at therapeutic levels (0.6-1.2 mEq/L).

Novel rapid treatments for depression

Non-Pharmacological Tx - Brain Boost & Banter

  • Electroconvulsive Therapy (ECT)
    • Indications: Severe TRD, psychotic features, catatonia, high suicide risk.
    • Procedure: 2-3 sessions/week for 6-12 total. Bilateral or RUL (Right Unilateral) placement.
    • Key SE: Transient memory loss (anterograde > retrograde), headache.

    ⭐ ECT has the most rapid antidepressant effect; often life-saving in severe cases with acute suicidality.

  • Psychotherapy ("Banter")
    • Cognitive Behavioural Therapy (CBT): Addresses negative thought patterns & maladaptive behaviours.
    • Interpersonal Psychotherapy (IPT): Focuses on relationship difficulties impacting mood.
    • Often adjunctive; improves coping, adherence & relapse prevention.
  • Other Neurostimulation
    • Repetitive Transcranial Magnetic Stimulation (rTMS): Non-invasive; targets Dorsolateral Prefrontal Cortex (DLPFC). Daily sessions for 4-6 weeks. Fewer cognitive SE than ECT.
    • Vagus Nerve Stimulation (VNS): Implanted device for chronic TRD; adjunctive.
    • Deep Brain Stimulation (DBS): Investigational; for highly refractory TRD.

High‑Yield Points - ⚡ Biggest Takeaways

  • TRD: Failure of ≥2 adequate antidepressant trials from different classes.
  • Augmentation strategies: Lithium, atypical antipsychotics (e.g., aripiprazole, quetiapine), thyroid hormone (T3).
  • Esketamine nasal spray: Rapid-acting NMDA antagonist for TRD.
  • ECT: Most effective for severe TRD, especially with psychotic features or suicidality.
  • rTMS: Non-invasive brain stimulation option.
  • Consider VNS for chronic TRD.
  • Always exclude pseudo-resistance (e.g., non-adherence, inadequate dose/duration).

Practice Questions: Treatment-Resistant Depression

Test your understanding with these related questions

A 30-year-old male was brought for evaluation, with a history of his 3-year-old son's death, 5 months prior, following a car accident. At the time of the accident, the patient was a witness. Since then, he has experienced symptoms of sadness, crying spells, feelings of hopelessness, poor sleep, and poor appetite. He has had suicidal thoughts on two occasions, but has not acted on them. He has not been attending work for the past 5 months. What is the likely diagnosis?

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Flashcards: Treatment-Resistant Depression

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Drug of choice for MDP is:

TAP TO REVEAL ANSWER

Drug of choice for MDP is:

Lithium

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