A 28-year-old man from Mumbai presents with a 4-year history of intense, irrational fear of heights. He avoids tall buildings, bridges, and even climbing stairs beyond the second floor, which has significantly impaired his work as an architect. He acknowledges that his fear is excessive and unreasonable, but when he approaches a height, he experiences acute anxiety, dizziness, and trembling. He has never had a panic attack or agoraphobic avoidance. His anxiety is limited to the height-related situation and resolves completely when he moves away from the height. He denies any traumatic fall or previous injury. What is the most likely diagnosis?

Explanation

## Diagnosis: Specific Phobia (Acrophobia) ### Core Features of Specific Phobia **Key Point:** Specific phobia is marked by intense, irrational fear of a **circumscribed object or situation**, with anxiety that is **triggered by and proportional to exposure** to that specific stimulus. This patient exhibits: 1. **Discrete phobic stimulus** — heights (acrophobia, from Greek *akron* = peak, *phobos* = fear) 2. **Immediate anxiety response** — trembling, dizziness, and acute anxiety triggered reliably by exposure to heights 3. **Avoidance behavior** — avoidance of tall buildings, bridges, stairs beyond second floor 4. **Insight** — acknowledges the fear is excessive and irrational 5. **Situational resolution** — anxiety resolves completely when stimulus is removed or distance is increased 6. **No panic attacks** — no unexpected, spontaneous panic episodes 7. **No agoraphobic avoidance** — avoidance is limited to height-related situations, not crowds or public spaces 8. **Functional impairment** — occupational impact (architect unable to work at heights) ### Diagnostic Criteria (DSM-5) | Criterion | Present in Case | | --- | --- | | Marked fear or anxiety about a specific object or situation | ✓ (heights) | | Phobic stimulus almost always provokes immediate anxiety | ✓ (trembling, dizziness) | | Avoidance or endurance with intense distress | ✓ (avoids tall buildings) | | Anxiety is out of proportion to actual danger | ✓ (acknowledged as irrational) | | Duration ≥6 months | ✓ (4 years) | | Causes clinically significant distress or functional impairment | ✓ (occupational impairment) | | Not better explained by another disorder | ✓ (no panic attacks, no agoraphobia) | **High-Yield:** The **stimulus-bound, circumscribed nature** of anxiety and **complete relief upon removal of the stimulus** are hallmarks of specific phobia and distinguish it from panic disorder (spontaneous) and GAD (pervasive). ### Common Specific Phobias (DSM-5 Subtypes) | Subtype | Example | | --- | --- | | **Animal type** | Fear of dogs, spiders, snakes | | **Natural environment type** | Fear of heights (acrophobia), storms, water | | **Blood-injection-injury type** | Fear of needles, medical procedures, blood | | **Situational type** | Fear of flying, driving, enclosed spaces (claustrophobia) | | **Other type** | Fear of choking, vomiting, loud sounds | **Clinical Pearl:** Acrophobia (fear of heights) is one of the most common specific phobias, affecting ~5% of the population. It may have evolutionary roots in threat detection at heights. ### Pathophysiology **Mnemonic: CER** — **Conditioning** (traumatic or observational learning), **Evolutionary preparedness** (innate predisposition to fear certain stimuli), and **Reinforcement** (avoidance reduces anxiety, negatively reinforcing the phobia). In this case, no trauma is reported, suggesting innate predisposition or observational learning. ### First-Line Treatment **Key Point:** **Exposure therapy (in vivo or virtual reality)** is the gold-standard, evidence-based treatment. Cognitive-behavioral therapy (CBT) and systematic desensitization are also effective. SSRIs are second-line for comorbid anxiety or depression. [cite:DSM-5 Diagnostic and Statistical Manual of Mental Disorders]