**Question:** Treatment of choice in severe depression is -

A. Fluoxetine
B. Imipramine
C. Electroconvulsive therapy (ECT)
D. Vagus nerve stimulation (VNS)

**Core Concept:**
Depression is a mental health disorder characterized by persistent feelings of sadness, loss of interest, and disturbed mood. It can be managed through various pharmacological and non-pharmacological approaches, depending on the severity and clinical presentation.

**Why the Correct Answer is Right:**
In severe depression, Electroconvulsive therapy (ECT) is the treatment of choice due to its rapid and significant improvement in symptoms. ECT involves delivering controlled electrical stimulation to the brain while the patient is under general anesthesia, inducing a brief seizure that alters neurotransmitter levels and enhances synaptic plasticity. This leads to improvement in mood and overall functioning.

**Why Each Wrong Option is Incorrect:**
A. Fluoxetine (SSRI) and B. Imipramine (Tricyclic antidepressant) are both pharmacological options for treating depression, but they may take weeks to weeks to show significant improvement.
C. Vagus nerve stimulation (VNS) is a newer non-invasive therapy that stimulates the vagus nerve to modulate neurotransmitter release, but it is typically reserved for patients with treatment-resistant depression, and is not as effective as ECT in severe cases.

**Clinical Pearl:**
In severe depression, ECT should be considered alongside a thorough evaluation to determine if it is an appropriate treatment option, taking into account the patient's age, medical comorbidities, and personal preferences. The decision should be based on a collaborative discussion between the patient, the treating physician, and a psychiatrist.

**Correct Answer:** Electroconvulsive therapy (ECT)