Sympathetic neural and cardiovascular responsiveness to involuntary stress-induced crying.

Acute and chronic emotional distress is associated with an elevated risk of adverse cardiovascular events in humans. However, our understanding of how complex emotional states impact autonomic and cardiovascular regulation in humans remains limited. The purpose of the present case study was to characterize muscle sympathetic nerve activity (MSNA) and peripheral hemodynamic responses to an involuntary mental stress-related lacrimation (i.e., crying) in a healthy, young female participant (age: 22 years; BMI: 27 kg/m²). Continuous heart rate (HR, electrocardiogram), beat-to-beat blood pressure (finger plethysmography), and MSNA (microneurography) were monitored during a 3-minute resting baseline and subsequent mental arithmetic task during which an unanticipated and involuntary crying was observed after 1 minute of the stress task. Sympathetic and hemodynamic reactivity during the first minute of mental arithmetic were quantified and compared to a retrospective dataset of healthy individuals in whom mental stress reactivity was similarly assessed (31 male, 30 female; age: 21±3 years; BMI: 25±6 kg/m²). Changes in systolic (SBP; Δ3 mmHg) and diastolic (DBP; Δ9 mmHg) blood pressure were comparable to the comparator group (SBP: Δ4±6 mmHg; DBP: Δ5±5 mmHg), while HR reactivity appeared slightly higher (Δ32 beats/min) than the comparator group (Δ22±11 beats/min). In contrast, MSNA burst frequency (BF: Δ22 bursts/min), incidence (BI: Δ20 bursts/100heartbeats), and total area (Δ971%) reactivity was substantially elevated relative to the comparator group (BF: Δ2±7 bursts/min; BI: Δ-3±11 bursts/100heartbeats; total area: Δ132±285%). These findings suggest that involuntary stress-induced crying is associated with substantial sympathetic activation beyond that observed during standard laboratory mental stress, despite modest changes in hemodynamic variables.