Stress Response Pattern of Heart Rate Variability in Patients with Functional Somatic Syndromes.

Functional somatic syndromes (FSSs) represent a clinically important group of disorders that are often stress-related. Their autonomic pathophysiology, including reduced heart rate variability (HRV), has been reported. However, the response pattern to mental stress and recovery in FSSs remains unclear. Thus, we aimed to clarify the pattern of autonomic stress response and recovery to mental arithmetic stress in patients with FSS compared to that in healthy controls. This cross-sectional study included 79 patients with FSS who visited the Department of Psychosomatic Medicine at a university hospital in Japan and 39 healthy controls. Following a mood questionnaire and obtaining epidemiologic information, HRV was measured during three periods (5 min each): relaxation baseline resting, stress (mental arithmetic task), and post-stress recovery period. The HRV analysis included inter-beat interval, low frequency power, and high frequency power. Compared to healthy controls, patients with FSS exhibited significantly higher scores on the mood questionnaire, prolonged duration of illness, and decreased functionality in daily activities. While the healthy control group showed a pronounced stress response pattern with a significant decrease in vagal HRV and recovery, the FSS group showed a "flat" vagal stress response pattern, and the HRV in the FSS group was lower at relaxation baseline, remained low during the stress, and did not change post stress. Patients with severe FSS exhibit an altered stress response pattern. Our results could provide significant clues for the diagnosis and treatment of such patients, as well as useful insights into the relationship between stress and illness.

Interoception and alexithymia are related to differences between the self-reported and the objectively measured physical activity in patients with chronic musculoskeletal pain.

OBJECTIVE: Patients with chronic musculoskeletal pain (CMP) have difficulty estimating their level of physical activity (PA). Factors associated with this difficulty have yet to be identified; however, identification could allow for increased accuracy in large-scale PA surveys, and enhanced self-management. The purpose of this study was to determine the relationship of interoception and alexithymia with differences between self-reported and objectively measured PA, and investigate factors as they relate to accurately self-reporting PA. METHODS: A cross-sectional survey of 33 patients with CMP and 32 healthy individuals was conducted from July 2018 to June 2019. We measured differences in Moderate to Vigorous Physical Activity (D-MVPA) using an accelerometer and self-report. A heartbeat tracking task (HTT) was used to measure interoception, and alexithymia was measured using the 20-item Toronto Alexithymia Scale (TAS-20). RESULTS: The CMP group (median 43.5 min/day, IQR 20.6-77.6) showed significantly higher D-MVPA values than the control group (median 22.5 min/day, IQR 6.7-34.9) (p < .001). In patients with CMP, D-MVPA positively correlated with TAS-20 (rho = 0.470, p = .006) and correlated negatively with HTT (rho = -0.390, p = .025). CONCLUSION: Inaccurate self-reported measurements of PA in patients with CMP are associated with alexithymia and interoception. This finding suggests that behavioral interventions targeting alexithymia and interoception in CMP patients could lead to improved self-monitoring.