A 52-year-old man with Major Depressive Disorder has been on fluoxetine 40 mg daily for 6 weeks with partial response. His psychiatrist is considering augmentation strategies. Which of the following augmentation agents is NOT supported by robust evidence in treatment-resistant depression?

Question

Accepted Answer

A. Benzodiazepines (alprazolam or lorazepam). ## Augmentation Strategies in Treatment-Resistant MDD

### Evidence-Based Augmentation Agents

**Key Point:** Augmentation (adding a second agent to an SSRI/SNRI) differs from switching. The three evidence-based augmentation strategies for treatment-resistant depression are:

| Augmentation Agent | Evidence Level | Mechanism | Typical Dosing |
| --- | --- | --- | --- |
| **Aripiprazole** | Strong (RCTs) | D2/5-HT1A partial agonist | 5–15 mg/day |
| **Lithium** | Strong (meta-analyses) | Enhances serotonergic neurotransmission, neuroprotection | 600–1200 mg/day (0.6–1.2 mEq/L) |
| **Thyroid hormone (T3)** | Moderate–Strong | Enhances antidepressant efficacy, increases receptor sensitivity | 25–50 mcg/day |
| **Benzodiazepines** | Weak (no RCT evidence) | GABA-A agonist; anxiolytic only | Variable |

### Why Benzodiazepines Are NOT Recommended for Augmentation

**High-Yield:** Benzodiazepines (alprazolam, lorazepam) are NOT evidence-based augmentation agents for MDD:

1. **No RCT evidence** — No randomized controlled trials demonstrate that benzodiazepines augment SSRI efficacy for core depressive symptoms (mood, anhedonia, guilt).

2. **Symptomatic relief only** — Benzodiazepines address anxiety and insomnia (common comorbidities in MDD) but do NOT treat the underlying depressive disorder.

3. **Dependence and tolerance** — Chronic benzodiazepine use carries risks of dependence, cognitive impairment, and paradoxical depression with long-term use.

4. **Not first-line** — Current guidelines (APA, NICE) recommend aripiprazole, lithium, or T3 augmentation before considering benzodiazepines, which are reserved for acute anxiety/insomnia management.

**Clinical Pearl:** A common clinical error is prescribing benzodiazepines to depressed patients with anxiety, assuming they "augment" antidepressant therapy. In reality, benzodiazepines are adjunctive for symptom control, not disease-modifying augmentation.

**Warning:** Do NOT confuse "adjunctive use" (benzodiazepines for anxiety/sleep) with "evidence-based augmentation" (aripiprazole, lithium, T3 for core depression). The question asks specifically about augmentation for treatment-resistant depression, where benzodiazepines lack RCT support.

Answer

B. Aripiprazole (atypical antipsychotic)

Answer

C. Lithium (mood stabilizer)

Answer

D. Thyroid hormone (T3 or T4)

A 52-year-old man with Major Depressive Disorder has been on fluoxetine 40 mg daily for 6 weeks with partial response. His psychiatrist is considering augmentation strategies. Which of the following augmentation agents is NOT supported by robust evidence in treatment-resistant depression?

Explanation

Augmentation Strategies in Treatment-Resistant MDD

Evidence-Based Augmentation Agents

Why Benzodiazepines Are NOT Recommended for Augmentation

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Augmentation Agent	Evidence Level	Mechanism	Typical Dosing
Aripiprazole	Strong (RCTs)	D2/5-HT1A partial agonist	5–15 mg/day
Lithium	Strong (meta-analyses)	Enhances serotonergic neurotransmission, neuroprotection	600–1200 mg/day (0.6–1.2 mEq/L)
Thyroid hormone (T3)	Moderate–Strong	Enhances antidepressant efficacy, increases receptor sensitivity	25–50 mcg/day
Benzodiazepines	Weak (no RCT evidence)	GABA-A agonist; anxiolytic only	Variable