Heart rate after trauma and the specificity of fear circuitry disorders

BACKGROUND: Fear circuitry disorders purportedly include post-traumatic stress disorder (PTSD), panic disorder, agoraphobia, social phobia and specific phobia. It is proposed that these disorders represent a cluster of anxiety disorders triggered by stressful events and lead to fear conditioning. Elevated heart rate (HR) at the time of an aversive event may reflect strength of the unconditioned response, which may contribute to fear circuitry disorders. METHOD: This prospective cohort study assessed HR within 48 h of hospital admission in 602 traumatically injured patients, who were assessed during hospital admission and within 1 month of trauma exposure for lifetime psychiatric diagnosis. At 3 months after the initial assessment, 526 patients (87%) were reassessed for PTSD, major depressive disorder, panic disorder, agoraphobia, social phobia, obsessive compulsive disorder and generalized anxiety disorder. RESULTS: At the 3-month assessment there were 77 (15%) new cases of fear circuitry disorder and 87 new cases of non-fear circuitry disorder (17%). After controlling for gender, age, type of injury and injury severity, patients with elevated HR (defined as ≥96 beats per min) at the time of injury were more likely to develop PTSD [odds ratio (OR) 5.78, 95% confidence interval (CI) 2.32-14.43], panic disorder (OR 3.46, 95% CI 1.16-10.34), agoraphobia (OR 3.90, 95% CI 1.76-8.61) and social phobia (OR 3.98, 95% CI 1.42-11.14). Elevated HR also predicted new fear circuitry disorders that were not co-morbid with a non-fear circuitry disorder (OR 7.28, 95% CI 2.14-24.79). CONCLUSIONS: These data provide tentative evidence of a common mechanism underpinning the onset of fear circuitry disorders.