Autonomic reactivity during reading of a somatic distress script in patients with somatic symptom disorder

Subjective and physiological reactivity to emotional stressors in somatic symptom disorder

OBJECTIVE

We examined whether autonomic flexibility to experimentally presented stressors is reduced in somatic symptom disorder (SSD) as this would point to reduced vagal control as a proposed indicator of emotion regulation deficits.

METHOD

In this experimental study, the influence of health-related and social stressors on subjective and physiological reactivity was investigated in 29 subjects with SSD without any medical condition SSD(mc-), 33 subjects with SSD with medical condition SSD(mc+) and 32 healthy controls at the age from 18 to 70 years. Self-report and physiological variables were measured before and after/during stressor exposure, using state ratings of symptom intensity, disability, tension and mood, heart rate (HR), and heart rate variability (HRV).

RESULTS

Overall, the tension increased and the mood worsened after exposure to stressors compared to pre-exposure. Compared to HC, the two SSD groups showed higher symptom intensity, disability, tension and worse mood. The SSD(mc-) group revealed higher HR than HC (p = .012, d = -0.77). Compared to pre-exposure, symptom impairment increased after social stressor exposure in SSD(mc-) (p < .001, d = 1.36). HRV-root mean square of successive differences (RMSSD) only decreased in HC during exposure (p = .003, d = -1.09), not in the SSD groups. The two SSD groups did not differ in their reactivity to stressors.

CONCLUSION

HRV in SSD, seems to respond less flexibly to stressors, potentially reflecting overall physiological disturbance through reduced parasympathetic influence on HR. Stress reactivity in SSD(mc-) and SSD(mc+) do not seem to differ.

Clarifying the link between psychopathologies and heart rate variability, and the sex differences: Can neuropsychological features serve as mediators?

BACKGROUND

Patients with common mental disorders (depression, anxiety, and somatic symptoms) often exhibit lower heart rate variability (HRV) than healthy individuals. Under the hypothesis that disorder status affects cognitive function, we examined whether neuropsychological features can be mediators between psychopathologies and HRV and possible sex differences.

METHODS

We recruited 359 individuals (aged 42.47 ± 12.23) with and without common mental disorders. Questionnaires were used to measure their psychopathologies. Eight tests from the Cambridge Neuropsychological Test Automated Battery were selected to measure neuropsychological functions. Resting-state HRV measurements were obtained for 5 min. The associations among these constructs were analyzed using multiple linear regression analysis and structural equation modelling.

RESULTS

Among women, Reaction Time (RTI, a task of psychomotor speed) indicator mediated the relationship between depression and low-frequency power (LF); Emotion Recognition Task (ERT, a task of emotional regulation) indicator mediated the relationship between health anxiety and high-frequency power (HF). Among men, Intra-Extra Dimensional Set Shift (IED, a task of shifting) indicator mediated the relationship between depression and LF; Match to Sample Visual Search (MTS, a task of selective attention) indicator mediated the relationship between health cognition and HF. The depression-RTI-LF pathway in women tended to lower HRV; whereas health anxiety-ERT-HF in women, depression-IED-LF and health cognition-MTS-HF in men tended to increase HRV.

LIMITATIONS

Possible medication effects; not directly measuring brain activity; only gathering resting-state HRV.

CONCLUSION

Our findings support the notion that neuropsychological features mediate the relationship between psychopathologies and HRV, and that sex differences exist.

Heart Rate Variability, Autonomic Reactivity, and Emotion Regulation during Sadness Induction in Somatic Symptom Disorder

BACKGROUND

Preliminary evidence suggests altered heart rate variability (HRV) and impaired emotion regulation (ER) in somatic symptom disorder (SSD). Moreover, HRV can be considered an index of ER. Yet, to date, research on HRV and emotional reactivity in SSD is scarce and findings are inconsistent. Thus, this study aimed to examine ER differences, HRV at rest, and in response to emotion induction in persons with SSD compared to controls.

METHODS

The sample comprised 44 persons with SSD (DSM-5; 79.5% female, Mage = 45.7, SD = 14.7) and 41 persons without SSD (non-SSD; 78% female, Mage = 44.2, SD = 14.7). We assessed the participants' somatic symptom severity, ER, and control variables (e.g., depressive symptoms). Frequency and time domain HRV by ECG and subjective emotional states were measured at rest, under sadness induction, and during recovery periods. We evaluated baseline between-group differences with t-tests, and HRV and emotional reactivity and recovery with repeated measures ANOVAs.

RESULTS

We found no significant differences in resting state HRV between persons with and without SSD. Regarding reactivity and recovery, SSD group showed lower reactivity in SDNN (standard deviation of NN interval) than non-SSD group. Moreover, SSD group reported more maladaptive ER techniques (e.g. rumination) and a higher effort to regulate their emotions during the experiment than non-SSD group.

CONCLUSIONS

The study indicated impaired ER in persons with SSD. This finding showed more clearly in self-report than in HRV. Further research on HRV reactivity including tasks evoking other negative emotions in persons with SSD is required.

Use of machine learning to diagnose somatic symptom disorder: Are the biomarkers beneficial for the diagnosis?

OBJECTIVES

We used machine learning to incorporate three types of biomarkers (respiratory sinus arrhythmia, RSA; skin conductance, SC; finger temperature, FT) for examining the performance of diagnosing somatic symptom disorder (SSD).

METHODS

We recruited 97 SSD subjects and 96 controls without psychiatric history or somatic distress. The values of RSA, SC and FT were recorded in three situations (resting state, under a cognitive task and under paced breathing) and compared for the two populations. We used machine learning to combine the biological signals and then applied receiver operating characteristic curve analysis to examine the performance of diagnosing SSD regarding the distinct indicators and situations. Subgroup analysis for subjects without depression/anxiety was also conducted.

RESULTS

FT was significantly different between SSD patients and controls, especially in the resting state and under paced breathing. However, the biomarkers (0.75-0.76) did not reveal an area under the curve (AUC) comparable with the psychological questionnaires (0.86). Combining the biological and psychological indicators gave a high AUC (0.86-0.92). When excluding individuals with depression/anxiety, combining three biomarkers (0.79-0.83) and adopting psychological questionnaires (0.78) revealed a similar AUC.

CONCLUSIONS

The performance of RSA/SC/FT was unsatisfactory for diagnosing SSD but became comparable when excluding comorbid depression/anxiety.

A simple version of resting-state heart rate variability interpretation for patients with affective disorders: A four-pattern perspective

Heart rate variability (HRV) is often considered as a biomarker reflecting well-being, but the clinical meaning of short-term resting-state HRV is not sufficiently defined. We assume that combining several common HRV indices as "HRV patterns" and using the patterns for screening purposes are meaningful approaches. Resting-state 5-min HRV data of 424 subjects were analyzed. Four of the most commonly used HRV indices were considered: standard deviation of normal-to-normal RR intervals, low-frequency power, high-frequency power and the ratio of low-frequency to high-frequency power. According to these indices, four HRV patterns were defined: normal pattern, low HRV pattern, relatively high sympathetic pattern, and relatively high vagal pattern. The associations between the demographics, lifestyles, personality traits, psychological states, and HRV patterns were explored: the low HRV pattern was positively associated with age, body mass index, and depression; the relatively high sympathetic pattern was positively associated with age and negatively associated with exercise habit; and the relatively high vagal pattern was negatively associated with having a steady job and novelty seeking. The pattern perspective may provide a convenient and evidence-based way to interpret resting-state HRV for patients with affective disorders.

The association between heart rate variability and skin conductance: a correlation analysis in healthy individuals and patients with somatic symptom disorder comorbid with depression and anxiety

Objective

To investigate the correlations between heart rate variability (HRV) and skin conductance (SC) in two populations under three different situations.

Methods

This cross-sectional study enrolled patients with somatic symptom disorder comorbid with depression and anxiety and healthy individuals without a psychiatric history. The biological signals were measured under three conditions: resting state, during a cognitive task and during paced breathing. Pearson’s correlation analysis and the generalized estimating equation were used to examine the correlations between SC and HRV in the two populations under the three situations.

Results

The study enrolled 97 patients with somatic symptom disorder comorbid with depression and anxiety and 96 healthy individuals. In healthy individuals, the ratio of low-frequency power to high frequency power (LF/HF) and normalized LF (LF%) were significantly correlated with SC in the resting state and during a cognitive task, but the correlation coefficients were low level. In patients with somatic symptom disorder comorbid with depression and anxiety, LF/HF and LF% did not show significant correlations with SC under any situation.

Conclusions

The two different populations and three situations might have affected the significance of the LF/HF-SC and LF%-SC correlations. The generally low correlations indicate that LF/HF and LF% cannot fully reflect the sympathetic cholinergic activity represented by SC.

Somatic symptom disorder: a scoping review on the empirical evidence of a new diagnosis

BACKGROUND

In 2013, the diagnosis of somatic symptom disorder (SSD) was introduced into the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). This review aims to comprehensively synthesize contemporary evidence related to SSD.

METHODS

A scoping review was conducted using PubMed, PsycINFO, and Cochrane Library. The main inclusion criteria were SSD and publication in the English language between 01/2009 and 05/2020. Systematic search terms also included subheadings for the DSM-5 text sections; i.e., diagnostic features, prevalence, development and course, risk and prognostic factors, culture, gender, suicide risk, functional consequences, differential diagnosis, and comorbidity.

RESULTS

Eight hundred and eighty-two articles were identified, of which 59 full texts were included for analysis. Empirical evidence supports the reliability, validity, and clinical utility of SSD diagnostic criteria, but the further specification of the psychological SSD B-criteria criteria seems necessary. General population studies using self-report questionnaires reported mean frequencies for SSD of 12.9% [95% confidence interval (CI) 12.5-13.3%], while prevalence studies based on criterion standard interviews are lacking. SSD was associated with increased functional impairment, decreased quality of life, and high comorbidity with anxiety and depressive disorders. Relevant research gaps remain regarding developmental aspects, risk and prognostic factors, suicide risk as well as culture- and gender-associated issues.

CONCLUSIONS

Strengths of the SSD diagnosis are its good reliability, validity, and clinical utility, which substantially improved on its predecessors. SSD characterizes a specific patient population that is significantly impaired both physically and psychologically. However, substantial research gaps exist, e.g., regarding SSD prevalence assessed with criterion standard diagnostic interviews.

The interplay of self-critical rumination and resting heart rate variability on subjective well-being and somatic symptom distress: A prospective study

OBJECTIVE

The aim of this prospective study was to investigate the association of self-critical rumination, autonomic function (indexed by a time domain metric of resting heart rate variability-RMSSD), subjective well-being and somatic symptom distress.

METHOD

84 healthy participants (73 females; mean age = 23.56, SD = 3.35 years) completed the Somatic Symptom Severity Scale of the Patient Health Questionnaire and Mental Health Continuum Short Form at two timepoints (at baseline and six months later). Resting heart rate variability (HRV) was assessed at baseline, along with content specific rumination using the Self-Critical Rumination Scale. Four moderation analyses were performed to test these associations.

RESULTS

The interaction between resting HRV and self-critical rumination significantly explained somatic symptom distress at baseline. For those participants who had high resting HRV, somatic symptom distress was basically independent from the level of self-critical rumination. At the same time, lower resting HRV was associated with higher somatic symptom distress, especially in the presence of more ruminative thoughts. Prospectively, however, the interaction between rumination and resting HRV was not a significant predictor of somatic symptom distress. The association between resting HRV and self-critical rumination did not explain the variance on subjective well-being, but subjective well-being was negatively related to self-critical rumination.

CONCLUSION

Our findings potentially indicate that self-critical rumination could have a long-term negative impact on psychological functioning, even in a non-clinical sample, and highlight that a lower level of parasympathetic activation, assessed with RMSSD, might be an important factor in the relationship of self-critical rumination and somatic symptom distress.

Association between Stroop tasks and heart rate variability features in patients with somatic symptom disorder

OBJECTIVE

Patients with somatic symptom disorder (SSD) may have declined parasympathetic activity and selective attention to negative information. We combined Stroop tasks and heart rate variability (HRV) measurements to explore the brain mechanism of SSD.

METHODS

104 SSD patients (64 women) and 100 healthy adults (76 women) received three Stroop tasks (the "cognitive" color-word Stroop, "emotional" emotion Stroop, and "cognitive and emotional" face-word Stroop) with low and high interference conditions. The key HRV indexes included high-frequency power (HF) and standard deviation of normal to normal RR intervals (SDNN). The generalized estimating equation model was used to examine the effects of SSD on three Stroop tasks performance (accuracy and reaction time) and HRV (HF and SDNN) controlling for sex, age, body mass index, and the levels of anxiety and depression.

RESULTS

For Stroop tasks, the significant group difference in emotion Stroop task with the high level of interference (SSD patients had lower accuracy than healthy ones) was only found in women. As for HRV, only men during color-word Stroop, women during emotion Stroop revealed significant between-group differences; SDNN in SSD men was higher than healthy men, and HF in SSD women was lower than healthy women controlling for the confounding factors. The significantly longer reaction time in SSD women than in healthy women diminished in the adjusted analysis.

CONCLUSION

Emotion Stroop task and HRV helps distinguish SSD patients from healthy adults, particularly in women. Sex-specific measures for early detection and intervention for SSD are suggested.