A 24-year-old woman with blood-injection-injury type specific phobia develops marked bradycardia and syncope when exposed to needles. This vasovagal response is preceded by which initial cardiovascular change?
- A Sustained bradycardia from the outset
- B Isolated hypertension without heart rate change
- C Initial tachycardia followed by parasympathetic overcompensation ✓
- D Ventricular arrhythmia
Correct answer: C. Initial tachycardia followed by parasympathetic overcompensation
Explanation
Blood-injection-injury phobia is unique among specific phobias because it shows a biphasic cardiovascular response: initial sympathetic activation (tachycardia, hypertension) followed by parasympathetic overcompensation causing bradycardia and vasovagal syncope. Other phobias show only sustained sympathetic activation without the vasovagal drop.
Reference: Kaplan and Sadock's Comprehensive Textbook of Psychiatry, 11th ed.
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