**Question:** A man hits his neighbour. Next day he feels that police is behind him and his brain is being controlled by radio waves by his neighbour. The probable diagnosis is

A. Acute Psychosis
B. Brainwave Synchronization Disorder
C. Hypnosis
D. Delusional Disorder

**Correct Answer:** .D. Delusional Disorder

**Core Concept:**
Delusional disorder is a mental health condition characterized by fixed, persistent beliefs (delusions) that are not based on reality and do not serve as a defense against anxiety or depression. These delusions can lead to abnormal behaviors and can cause significant distress or impairment in daily functioning.

**Why the Correct Answer is Right:**
In this case, the man experiences delusions about police being behind him and being controlled by radio waves. These delusions are not based on reality and do not arise as a defense mechanism against anxiety or depression. The core concept of delusional disorder fits the presented symptoms perfectly.

**Why Each Wrong Option is Incorrect:**

A. Acute Psychosis: Psychosis is a mental disorder characterized by a disordered thinking and perception. However, the correct diagnosis is delusional disorder as the man's symptoms are more specific and persistent, not transient or secondary to another condition.

B. Brainwave Synchronization Disorder: This disorder is not a known mental health condition and does not align with the presented symptoms. The correct diagnosis, delusional disorder, is a more suitable explanation for the man's experiences.

C. Hypnosis: Hypnosis is a state of heightened suggestibility, often used for therapeutic purposes or entertainment. The man's symptoms are persistent, not transient, and do not serve a purpose like reducing anxiety or depression.

**Clinical Pearl:**
Delusional disorder can be challenging to diagnose due to the presence of delusions, but it is essential to consider this possibility when assessing patients exhibiting persistent, distressing thoughts or beliefs not explained by other conditions.

In this scenario, the correct diagnosis is Delusional Disorder (Option D) because:
1. The symptoms are specific and persistent, not transient or secondary to another condition.
2. The delusions are not serving a purpose like reducing anxiety or depression.
3. The core concept of delusional disorder fits the presented symptoms better than the other options.