The genesis and presentation of anxiety in disorders of autonomic overexcitation.

INTRODUCTION: We investigated the genesis and presentation of previously-reported anxiety in disorders of autonomic overexcitation in relation to interoception, body vigilance and trauma to test our hypothesis that patients with the postural tachycardia syndrome (PoTS), vasovagal syncope (VVS) and essential hyperhidrosis (EH) represent atypical anxiety phenotypes in whom affective symptoms are more related to apprehension and vigilance of physiological (interoceptive) feedback than neurotic or trauma-related factors.

METHODS: The Anxiety Sensitivity Index, Body Vigilance Scale, Self-consciousness Scale, Childhood Traumatic Events Scale and heartbeat tracking tasks were completed by 23 healthy controls, 21 PoTS, 20 EH and 20 VVS patients. Interoceptive accuracy (IA) was assessed during supine rest (9min), isometric exercise (3min), cold pressor (90s) and head up tilt (HUT) (9min).

RESULTS: In comparison to controls, PoTS, VVS and EH patients reported increased symptoms of somatic anxiety but not of social anxiety/self-consciousness or trauma. Autonomic patients' IA was diminished and consistently underestimated even during autonomic arousal compared to controls. Controls and EH IA negatively correlated with somatic anxiety/hypervigilance, whereas PoTS and VVS IA and somatic anxiety/vigilance positively correlated.

CONCLUSIONS: Affective symptoms in PoTS, VVS and EH appear to be driven by anxiety and vigilance of physical sensations/symptoms, rather than trauma or neurosis. Increased somatic vigilance/anxiety in PoTS and VVS may be due to interoception being anxiogenic in these cohorts. Diminished interoception may be due to a common central dysregulation, as both sudomotor and cardiovascular forms of autonomic dysfunction had comparable IA deficits. These findings provide a possible therapeutic pathway for psychological symptoms in PoTS, VVS and EH.