A middle aged man presented with pain in back, lack of interest in recreational activities, low mood, lethargy, decreased sleep and appetite for two months. There was no history suggestive of delusions of hallucinations. He did not suffer from any chronic medical illness. There was no family history of psychiatric illness. Routine investigations including haemogram, renal function tests, liver function tests electrocadiogram did not reveal any abnormality. This patient should be treated with :

**Core Concept**
The patient's presentation suggests a diagnosis of Major Depressive Disorder (MDD), a mood disorder characterized by persistent and intense feelings of sadness, hopelessness, and a lack of interest in activities, which significantly impair daily functioning.

**Why the Correct Answer is Right**
The patient's symptoms, such as low mood, lethargy, decreased sleep and appetite, lack of interest in recreational activities, and lack of delusions or hallucinations, are consistent with a diagnosis of MDD. The absence of chronic medical illness and family history of psychiatric illness further supports this diagnosis. The patient's symptoms have been present for two months, which meets the duration criteria for a diagnosis of MDD. Selective serotonin reuptake inhibitors (SSRIs) are a first-line treatment for MDD due to their efficacy and relatively favorable side-effect profile.

**Why Each Wrong Option is Incorrect**

* **Option B:** While atypical antipsychotics may be used as adjunctive therapy in treatment-resistant depression, they are not typically used as first-line treatment for MDD.
* **Option C:** Mood stabilizers, such as lithium, are primarily used to treat bipolar disorder, and are not typically used as first-line treatment for MDD.

**Clinical Pearl / High-Yield Fact**
SSRIs are a first-line treatment for MDD due to their efficacy and relatively favorable side-effect profile, but they may take 2-4 weeks to start showing clinical benefit.

**Correct Answer:** A.

✓ Correct Answer: B. Seraline.