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A key diagnostic criterion of Somatic Symptom and related Disorders (SSD) comprises significant distress and excessive time-and-energy consuming thoughts, feelings, and behavior pertaining to somatic symptoms. This diagnostic criterion is lacking in central sensitivity syndromes (CSS), such as fibromyalgia, irritable bowel syndrome, and chronic fatigue syndrome. This strong emphasis on disturbed psychological processing of somatic symptoms, suggests that psychological flexibility is low in SDD. Psychological flexibility is defined as the ability to approach difficult or challenging internal states (thoughts, emotions, and bodily sensations) in a non-judgmental, mindful way, and being committed to pursue one's values. To clarify the potential significance of psychological flexibility in SSD, we examined its levels in 154 people referred to specialized treatment for SDD, as compared to reference groups from the general population encompassing 597 people with CSS and 1422 people without SSD or CSS (controls). Mean levels of psychological flexibility (adjusted for demographic covariates) were lowest for SSD and highest for controls (F = 154.5, p < 0.001, pη 2  = 0.13). Percentages of people with low psychological flexibility (<0.8 SD below the mean of controls) were: SSD 74%, CSS 42%, controls 21%. In SSD, higher psychological flexibility was associated with better mental health (β = 0.56, p < 0.001), but interaction analysis rejected that psychological flexibility preserved health when having more severe somatic symptoms (β ≤ 0.08, p ≥ 0.10). The results indicate that lower psychological flexibility is a prevalent problem in SSD that is associated with lower mental health. This suggests that it is worthwhile to take account of psychological flexibility in SSD in screening, monitoring, and therapy., Competing Interests: Declaration of competing interest The authors declare no conflicts of interest., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Background: Acceptance and Commitment Therapy (ACT) plays an important role in the treatment of patients with refractory Somatic Symptom Disorder and related disorders with complex problems and/or somatic or psychiatric comorbidity (complex SSD)., Aim: To gain insight into the possible role of (experiential) acceptance in improved quality of life during and after treatment., Method: Observational longitudinal study in 41 patients with complex SSD treated at Altrecht Psychosomatic Medicine Eikenboom. They completed online questionnaires around the start and completion of treatment and after six months of follow-up. Assessed were experiential acceptance (AAQ-II-NL) and three aspects of quality of life (RAND-36: mental health, physical functioning, general health perception). The associations between changes in acceptance and quality of life were determined., Results: Acceptance increased significantly from treatment initiation to follow-up. Mental health increased significantly between start and end of treatment, and general health perception increased significantly in the follow-up period. Physical functioning did not change. During treatment, an increase in acceptance was significantly associated with improvement in mental health and general health perception; during follow-up, an increase in acceptance was associated with an improvement in mental health., Conclusion: The current study demonstrates that an increase in experiential acceptance goes hand in hand with an improvement in mental health and general health perception. These results indicate the potential importance of acceptance-based treatment in patients with complex SSD. Experimental research with more frequent measurements is needed to test a temporal relationship between (first) increased acceptance and (then) improved quality of life.

Objective: Pre-to-post mean group differences of intermittently assessed generic outcome variables may not capture all relevant treatment-related changes in individual patients with somatic symptom disorder (SSD). Aim of this multiple single-case observational pilot project was to find out whether the Experience Sampling Method (ESM) and dynamic symptom networks may offer new opportunities in evaluating treatment outcomes for individual patients with SSD., Methods: Patients with SSD (N = 6 in study 1, N = 7 in study 2) received a self-compassion training in a tertiary care mental health expert center. Using a single-case pre-post treatment observational design, intensive longitudinal data were collected with ESM. A brief questionnaire was presented via the patient's smartphone three times per day for 16 weeks before, during and after the training in study 1, and for 5 weeks before and 5 weeks after the training in study 2. Eleven questions comprised somatic symptoms, functional disability, stress, self-compassion, and acceptance of affect; three personalized questions comprised self-chosen affects and an additional symptom., Results: Sufficient observations for means and network comparison were obtained for 11 and 10 patients, respectively. After the training, self-compassion was significantly increased in 10 patients, functional disability, stress and affect improved in 6 patients, and (although not a treatment goal) somatic symptoms decreased in 6 patients. Dynamic symptom networks significantly changed in 5 patients., Conclusion: Patient-specific changes in means and dynamic symptom networks were observed after self-compassion training. In future clinical trials, single-case ESM may offer new opportunities to evaluate treatment outcomes in patients with SSD., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background: Patients with mental health disorders often have difficulty perceiving associations between multiple symptoms, such as inter-relations between somatic and psychological symptoms. This difficulty may be particularly challenging in patients with complex disorders. Individual dynamic network analysis may provide novel diagnostic and treatment possibilities because it can create a starting point for a personalized approach in complex cases in tertiary mental health care expert centres, where standard protocolized interventions were insufficiently effective., Aim: To explore the possibilities provided by dynamic network technologies in the care of patients in tertiary care expert centres., Method: Overview of these possibilities, with a focus on somatic symptom disorder., Results: Intensive longitudinal data can be obtained using a short and personalized questionnaire that is presented via a patient's smartphone a few times per day during several weeks. These data are then converted to patient-specific dynamic symptom networks using time series analysis. These networks display how variations over time in somatic and mental symptoms and other factors (such as specific situations) mutually influence each other in daily life. They also provide information about cause-effect associations., Conclusion: Dynamic symptom networks provide insight into the associations between symptoms and other factors and can be used to personalize treatment goals and interventions in tertiary care expert centres. Furthermore, these networks create opportunities to examine the (patient-tailored) effects of personalized interventions.

The main objective of the study is to determine if non-specific physical symptoms (NSPS) in people with self-declared sensitivity to radiofrequency electromagnetic fields (RF EMF) can be explained (across subjects) by exposure to RF EMF. Furthermore, we pioneered whether analysis at the individual level or at the group level may lead to different conclusions. By our knowledge, this is the first longitudinal study exploring the data at the individual level. A group of 57 participants was equipped with a measurement set for five consecutive days. The measurement set consisted of a body worn exposimeter measuring the radiofrequency electromagnetic field in twelve frequency bands used for communication, a GPS logger, and an electronic diary giving cues at random intervals within a two to three hour interval. At every cue, a questionnaire on the most important health complaint and nine NSPS had to be filled out. We analysed the (time-lagged) associations between RF-EMF exposure in the included frequency bands and the total number of NSPS and self-rated severity of the most important health complaint. The manifestation of NSPS was studied during two different time lags - 0-1 h, and 1-4 h - after exposure and for different exposure metrics of RF EMF. The exposure was characterised by exposure metrics describing the central tendency and the intermittency of the signal, i.e. the time-weighted average exposure, the time above an exposure level or the rate of change metric. At group level, there was no statistically significant and relevant (fixed effect) association between the measured personal exposure to RF EMF and NSPS. At individual level, after correction for multiple testing and confounding, we found significant within-person associations between WiFi (the self-declared most important source) exposure metrics and the total NSPS score and severity of the most important complaint in one participant. However, it cannot be ruled out that this association is explained by residual confounding due to imperfect control for location or activities. Therefore, the outcomes have to be regarded very prudently. The significant associations were found for the short and the long time lag, but not always concurrently, so both provide complementary information. We also conclude that analyses at the individual level can lead to different findings when compared to an analysis at group level., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Objective: The aim of this concept mapping study was to identify the structure and alleged importance of perpetuating factors of functional somatic symptoms (FSS) from the perspective of professionals. Further, we examined to which extent these factors have been addressed in scientific literature., Methods: Ninety-nine perpetuating factors were sorted with respect to content using a card-sorting task by 61 experienced clinicians (62.3% psychologists, 75.4% female, mean age: 45.7 [SD: 10.6] years, mean duration of experience in treating FSS patients: 10.5 [SD: 7.6] years). These factors had been derived from in-depth interviews with 12 clinicians, with extensive experience in treating FSS. Thirty-eight clinicians rated the importance of the 99 factors on a scale ranging from 1 ('not important at all') to 10 ('extremely important')., Results: Hierarchical cluster analysis revealed three overarching domains of perpetuating factors: 'Hypochondria', 'Social and relational problems' and 'Symptom-related emotions and habits'. These domains comprised 16 clusters, which were rated on importance between 6.1, 'Adverse physical factors and counterproductive lifestyle', and 7.8, 'Frustration and despair regarding the symptoms'. All clusters have been addressed in scientific literature., Conclusions: This study revealed an encompassing hierarchical structure of somatic, emotional, cognitive, behavioral, and social factors of importance in the perpetuation of FSS based on expert opinions. This structure will guide the development of personalized treatment of FSS., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Based on the concept of somatization, psychological distress can be experienced as symptoms of physical illness. This suggests a close-fitting intra-individual association between bodily complaints and mood in patients with somatoform disorder (SFD). The contemporaneous day-to-day complaints-mood association was investigated in patients with severe chronic SFD using an ecological momentary assessment (EMA) design. Eleven patients, who had recently received specialized tertiary care treatment for severe chronic SFD, kept an online electronic diary for four consecutive weeks. They were prompted at intervals throughout the day to complete questions on their momentary primary symptoms (pain and fatigue), and mood state (negative and positive). For each measure, day-mean aggregated values were computed and analyzed using linear multilevel (mixed model) regression analysis. Fixed factor results showed that symptoms were associated with both negative mood state (β = 0.47) and positive mood state (β = -0.59). Random results, however, indicated large inter-individual differences, with correlations varying between 0.17 and 0.99 for negative affect, and between -0.88 and 0.14 for positive affect. A substantial day-to-day contemporaneous association between symptoms and affect across subjects, as well as large inter-individual differences in this association, were demonstrated in patients with severe chronic SFD. EMA-data showing the relationship between both negative and (inverse) positive mood and complaints has potential clinical relevance: providing SFD patients with feedback consisting of their personal day-to-day concurrency graph may promote their understanding of their own complaints in a broader context than the somatic area., (© 2015 Scandinavian Psychological Associations and John Wiley & Sons Ltd.)

Measurement error is omnipresent in psychological data. However, the vast majority of applications of autoregressive time series analyses in psychology do not take measurement error into account. Disregarding measurement error when it is present in the data results in a bias of the autoregressive parameters. We discuss two models that take measurement error into account: An autoregressive model with a white noise term (AR+WN), and an autoregressive moving average (ARMA) model. In a simulation study we compare the parameter recovery performance of these models, and compare this performance for both a Bayesian and frequentist approach. We find that overall, the AR+WN model performs better. Furthermore, we find that for realistic (i.e., small) sample sizes, psychological research would benefit from a Bayesian approach in fitting these models. Finally, we illustrate the effect of disregarding measurement error in an AR(1) model by means of an empirical application on mood data in women. We find that, depending on the person, approximately 30-50% of the total variance was due to measurement error, and that disregarding this measurement error results in a substantial underestimation of the autoregressive parameters.

Chronic severe somatoform disorder (SFD) is resistant to treatment. In a prospective observational study, we evaluated an intensive multidisciplinary treatment focusing on body-related mentalization and acceptance. Patients included in the study were 183 (146 women, 37 men) of 311 eligible patients with chronic severe SFD, referred consecutively to a specialized tertiary care center between 2002 and 2009. Primary outcome measures were somatic symptoms (SCL-90) and health-related quality of life (EuroQol 5-Dimensional [EQ-5D]). These measures were assessed four times before treatment (on intake, twice during an observation period, at start of treatment) and four times after treatment (during follow-up for 2 years). Multilevel analysis was used to separate effects of time (maturation) and treatment. Results revealed significant improvements in SCL-90 somatic symptoms (d = 0.51), EQ-5D index (d = 0.27), and EQ visual analogue scale (d = 0.56). Significant reductions were also observed in SCL-90 anxiety, depression, and overall psychopathology as well as in medical consumption associated with psychiatric illness (Trimbos/iMTA Questionnaire for Costs Associated With Psychiatric Illness). Large interindividual differences were found in treatment outcome. The long-term improvement seen in many patients suggests that intensive multidisciplinary tertiary care treatment is a useful approach to chronic severe SFD.

Introduction: Experimental animal studies provided evidence for a synergistic effect of immunological and psychological stressors on subsequent sickness behaviours. Up to now, little corroborating evidence for such synergy exists for humans, in whom it may provide a mechanism leading to the expression of functional somatic symptoms. The aim of the present study was to determine an interaction between stress(-vulnerability) and an immunological activation on experimental pain sensitivity, i.e., pressure pain threshold and tolerance in healthy humans., Methods: In healthy female participants (n=25, mean age 22.3 years), negative affectivity (NA) and experienced stress were assessed by questionnaire before receiving a Salmonella typhi vaccine or saline control in a randomized blinded cross-over design. Pressure pain threshold was assessed at the lower back and calves and pain tolerance was assessed at the thumbnail, before and six hours after each injection., Results: Vaccination induced leukocytosis (+100%) and increased serum IL-6 (+670%). NA predicted decreased pain tolerance after vaccination (β=-.57, p=.007), but not after placebo (β=.25, p=.26). Post-hoc analyses also demonstrated an association with administration order., Discussion: NA moderated the effects of inflammation on pain tolerance. This finding is consistent with a synergistic model whereby inflammation may lower the threshold for pain reporting in individuals with increased vulnerability for somatic symptom reporting., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Background: Factors that are associated with pain perception remain incompletely understood, especially in the visceral pain field. Therefore, the current study aimed to investigate possible psychological and biological predictors of visceral pain sensitivity in healthy subjects., Methods: In a sample of 59 healthy premenopausal female subjects on hormonal contraceptives, measures of gastrointestinal (GI) symptoms in daily life, trait and state anxiety, depression, serum cortisol concentrations and serum levels of interleukin-6 (IL-6) were obtained, followed by assessment of rectal distension pain sensitivity measures (i.e., rectal distension sensory threshold, pain threshold and pain ratings for discrete rectal distension stimuli)., Results: Regression analyses showed that more GI symptoms in daily life predicted a lower pain threshold. Higher levels of state anxiety predicted a lower pain threshold. Higher cortisol concentrations predicted lower pain ratings. IL-6 was positively related to GI symptoms but was a non-significant predictor of pain threshold in the multiple regression analysis., Conclusions: Similar to findings in patients with functional GI symptoms, we showed that subclinical GI symptoms predict visceral pain sensitivity. In line with somatic pain findings, state but not trait anxiety was found to predict visceral pain sensitivity. Our finding on serum cortisol as positive predictor of pain sensitivity might be interpreted in light of immunosuppressive effects of cortisol. Our finding on the role of IL-6 in GI symptoms is promising for understanding GI complaints in patients and needs further investigation., (© 2013 European Pain Federation - EFIC®)

Background: Although it is generally the severity of a patient's symptoms and impairments which determines the amount of care allocated to patients with somatoform disorders, comorbidity appears to be an additional relevant factor. A number of studies in different populations with somatoform disorders have shown that these disorders overlap with mood disorders, anxiety disorders, and personality disorders. So far, however, little is known about comorbidity in patients in tertiary care who are suffering from severe somatoform disorders., Aim: To determine comorbidity of mood, anxiety and personality disorders in patients in tertiary care suffering from severe somatoform disorders., Method: The study was based on a sample of 340 patients with dsm-iv-tr somatoform disorder who were awaiting treatment in a specialised care centre. The sample was examined by means of structured clinical assessment of dsm-iv-tr axis I and axis II disorders., Results: 49.4% of the 340 participants was diagnosed with a mood disorder, 62.1% with an anxiety disorder and 50.6% with a personality disorder., Conclusion: Patients in tertiary care suffering from (severe) somatic disorders show higher comorbidity of mood, anxiety and personality disorder than previously reported for somatoform disorder patients in primary and secondary care.

Background: Patients with severe somatoform disorder (in secondary and tertiary care) typically experience functional impairment associated with physical symptoms and mental distress. Although psychotherapy is the preferred treatment, its effectiveness remains to be demonstrated., Aims: To examine the effectiveness of psychotherapy for severe somatoform disorder in secondary and tertiary care compared with treatment as usual (TAU) but not waiting-list conditions., Method: Main inclusion criteria were presence of a somatoform disorder according to established diagnostic criteria and receiving psychotherapy for somatoform disorder in secondary and tertiary care. Both randomised and non-randomised trials were included. The evaluated outcome domains were physical symptoms, psychological symptoms (depression, anxiety, anger, general symptoms) and functional impairment (health, life satisfaction, interpersonal problems, maladaptive cognitions and behaviour)., Results: Ten randomised and six non-randomised trials were included, comprising 890 patients receiving psychotherapy and 548 patients receiving TAU. Psychotherapy was more effective than TAU for physical symptoms (d = 0.80 v. d = 0.31, P<0.05) and functional impairment (d = 0.45 v. d = 0.15, P<0.01), but not for psychological symptoms (d = 0.75 v. d = 0.51, P = 0.21). These effects were maintained at follow-up., Conclusions: Overall findings suggest that psychotherapy is effective in severe somatoform disorder. Future randomised controlled studies should examine specific interventions and mechanisms of change.

Objective: Somatoform disorders (SDs) are characterized by chronic multiple functional somatic (FS) symptoms. It has been suggested that infections may be triggers for FS symptoms to occur, pointing to the immune system as a pathogenic factor in their development. The current study aimed to compare the prevalence of infections (i.e., infection load) in the history of patients with SDs with that of matched controls., Methods: Samples (n = 185) were identified in the Psychiatric Case Register Middle Netherlands and the Julius General Practitioners Network. Patients with an SD diagnosis in the Psychiatric Case Register Middle Netherlands were compared with matched persons without somatoform complaints (controls) on their infection load in two periods before the date of the psychiatric diagnosis or a matched date for the controls (i.e., the total period for which data were available and a 3-year period). Infection load was defined as the total number of infections documented in the Julius General Practitioners Network., Results: Patients with SD had significantly more infections than did controls in both periods (total period: mean [standard error] = 0.87 [0.10] versus 0.51 [0.06], z = -3.08, p = .002; 3-year period: 3.44 [0.47] versus 2.15 [0.50], z = -2.91, p = .004)., Conclusions: Results show that patients with SD have a higher infection load preceding their diagnosis as compared with matched controls, implicating that infection load may indeed predispose for developing FS symptoms. These findings emphasize the importance of further research on immunological mechanisms in FS symptoms. Limitations of the study are discussed.

Objective: Patients with fibromyalgia have shown hyporeactive autonomic nervous system (ANS) responses to physical stressors, augmented pain to ANS changes, and heightened negative emotions, which can increase pain. This study examined ANS reactivity to negative emotions and its association with pain in fibromyalgia and control participants., Methods: Sixty-two women with fibromyalgia and 59 women in a control group recalled neutral, and anger- and sadness-eliciting experiences while ANS activity was monitored. Clinical and experimental pain were assessed in response to each emotion., Results: Compared with neutral recall, heart rate (p = .050), mean arterial pressure (p < .001), and high-frequency heart rate variability (p = .012) increased in response to sadness, whereas heart rate decreased (p = .002) and mean arterial pressure increased (p < .001) in response to anger; however, ANS responses did not differ between patients and control participants (all p > .29). Among patients only, decreased preejection period (anger-pain threshold: r = 0.31, p = .018) and total peripheral resistance in response to negative emotions (anger-pain tolerance: r = 0.35, p = .025; sadness-pain threshold: r = 0.51, p < .001; sadness-pain tolerance: r = 0.61, p < .001) correlated with more pain., Conclusions: These data suggest that the ANS is not hyporesponsive to elicited emotions in fibromyalgia; however, patients with a larger pain response showed an ANS response pattern reflecting heightened β-adrenergic and reduced α-adrenergic reactivity. Future research should test whether a specific ANS response pattern to emotions is a consequence of increased pain or whether it amplifies pain.

Introduction: Idiopathic Environmental Intolerance (IEI) attributed to electromagnetic fields (EMF) refers to self-reported sensitivity mainly characterised by the attribution of non-specific physical symptoms to low-level EMF exposure emitted from sources such as mobile phones. Scientific studies have not provided evidence for the existence of IEI-EMF, but these studies did not resemble the real-life situation or suffered from poor exposure characterisation and biased recall of health symptoms. To improve existing methods for the study of IEI-EMF, an Ecological Momentary Assessment (EMA) study is designed., Methods and Analysis: The study is an EMA study in which respondents carry personal exposure metres (exposimeters) that measure radiofrequency (RF) EMF, with frequent assessment of health symptoms and perceived EMF exposure through electronic diary registration during five consecutive days. Participants will be a selection from an epidemiological study who report to be sensitive to RF EMF. The exposimeters measure electric field strength in 12 frequency bands. Diary questions include the occurrence and severity of 10 non-specific physical symptoms, mood states and perceived exposure to (sources of) EMF. The relationship of actual and perceived EMF exposure and mood with non-specific physical symptoms will be analysed using multilevel regression analysis with time-shift models., Discussion: The study has several advantages over previous studies, including assessment of personal EMF exposure and non-specific physical symptoms by an ecological method with a minimised chance of recall bias. The within-person design reduces confounding by time-stable factors (eg, personal characteristics). In the conduct of the study and the analysis and interpretation of its outcomes, some methodological issues including a high participant burden, reactivity, compliance to the study protocol and the potential of chance findings due to multiple statistical testing will be accounted for and limited as much as possible.

Smartphones were used in an online Ecological Momentary Assessment (EMA) design to test prodromal functioning relative to the interictal state in migraine patients. Eighty-seven participants completed an electronic diary 4 times daily during 3-6 weeks to monitor their migraine attacks. Twice daily the diary additionally included 16 multi-answer questions covering physical symptoms (30 items), cognitive-affective functioning (25 items) and external factors (25 items). Eight clustered prodromal features were identified in the current study: sensory sensitivity, pain/stiffness, fatigue, cognitive functioning, positive affect, negative affect, effort spent and stressors encountered. Per feature, individual change scores with interictal control days--excluding 24-hour post-attack recovery--were computed for six 12-hour pre-attack time windows covering three prodromal days. Linear mixed model (fixed-effect) analysis established significant increases in sensory sensitivity, pain/stiffness and fatigue, and a tendency for increased negative affect, in the 12 hours prior to the attack. Positive affect and cognitive functioning were impaired both in the 25-36 hour and--more strongly--in the 12-hour time window before the attack. No effects were found for effort spent and stressors encountered. Exploratory (random effect) analysis revealed significant individual differences in the change scores in sensory sensitivity, pain/stiffness, fatigue and negative affect. It is concluded that the prodromal change in migraine--relative to interictal functioning--predominantly exists within the last 12 hours before attack onset. Individual diversity is large, however. Future research should zoom in to identify prodrome development within the 12 pre-attack hours as well as to isolate individual patterns.

Introduction Experimental pain studies can provide unique insight into the dimensions of pain and into individual differences in pain responsiveness by controlling different aspects of pain-eliciting stimuli and pain measures. In experimental pain studies, pain responsiveness can be assessed as pain threshold, pain tolerance or pain ratings. The test-theoretical qualities of these different measures, however, have not yet been completely documented. In the current study, several of these qualities were investigated in a pain experiment applying different algometric techniques. The objective of the study was to investigate the reliability (test-retest) and the convergent validity (correspondence) of the different methods found in the literature of measuring pressure-pain threshold, and the interrelationship between pressure-pain threshold, pressure-pain tolerance, and pressure-pain ratings. Methods Sixty-six healthy female subjects were enrolled in the study. All pressure stimuli were applied by a trained investigator, using a digital algometer with a 1 cm2 rubber tip. Pressure-pain thresholds were assessed repeatedly on six different body points (i.e. left and right calf one third of total calf muscle length below the popliteal space), the lower back (5 cm left and right from the L3), and left and right forearm (thickest part of brachioradialis muscle). Next, pressure-pain tolerance was measured on the thumbnail of the non-dominant hand, followed by rating affective and sensory components (on visual analogue scales) of a stimulus at tolerance level. Last, affective and sensory ratings were obtained for two pressure intensities. Results With intraclass correlations above .75 for pain responses per body point, test-retest reliability was found to be good. However, values obtained from all first measurements were significantly higher as compared with the two succeeding ones. Convergent validity of pain thresholds across different body points was found to be high for all combinations assessed (Cronbach's alpha values >.80), but the highest for bilateral similar body parts (>.89). Finally, principal components analysis including measures of threshold, tolerance and pain ratings yielded a three-factor solution that explained 81.9% of the variance: Moderate-level stimulus appraisal & pain tolerance; Pain threshold; Tolerance-level stimulus appraisal. Conclusion and implications Findings of the current study were used to formulate recommendations for future algometric pain studies. Concerning pressure-pain threshold, it is recommended to exclude first measurements for every body point from further analyses, as these measurements were found to be consistently higher compared with the following measurements. Further, no more than two consecutive measurements (after the first measurement) are needed for a reliable mean threshold value per body point. When combining threshold values of several body points into one mean-aggregated threshold value, we suggest to combine bilateral similar points, as convergent validity values were highest for these combinations. The three-factor solution that was found with principal components analyses indicates that pressure-pain threshold, subjective ratings of moderate intensity stimuli, and subjective ratings of the maximum (tolerance) intensity are distinct aspects of pain responsiveness. It is therefore recommended to include a measure of each of these three dimensions of pain when assessing pressure pain responsiveness. Some limitations of our study are discussed.

Background: Slow breathing and heart coherence training are being offered increasingly as treatments for anxiety, depression and stress-related mental and somatic complaints. Both of these interventions are aimed at influencing (i.e. increasing or optimising) heart rate variability and the mechanism involved is described in terms such as heart coherence, resonance breathing and heart-brain communication., Aim: To find out whether treatment effects are indeed based on the optimisation of heart rate variability., Method: Our literature search focused on 1) the assumption that poor mental health is definitely linked to deviant heart rate variability, and 2) the assumption that optimising heart rate variability leads specifically to a reduction of complaints and symptoms., Results: There is insufficient evidence to support these two assumptions., Conclusion: Slow breathing and heart coherence training probably achieve their effects as a result of non-specific psychological mechanisms.

A non-clinical group high on heterogeneous medically unexplained symptoms (MUS; n=97) was compared with healthy controls (n=66) on the within-subject relationships between physiological measures using multilevel path analysis. Momentary experienced somatic complaints, mood (tension and depression), cardiac autonomic activity (inter-beat intervals, pre-ejection period (PEP), and respiratory sinus arrhythmia (RSA)) and respiration (rate and partial pressure of CO(2) at the end of a normal expiration) were monitored for 24 h using electronic diary and ambulatory devices. Relationships between measures were controlled for diurnal variation and individual means. Only subtle group differences were found in the diurnal rhythm and in the within-subject relationships between physiological measures. For participants high on MUS, within-subject changes in bodily symptoms were related to changes in mood, but only marginally to the physiological measures. Results of the current path analysis confirm the subordinate role of cardiac autonomic and respiratory parameters in MUS.

The predictive value for spontaneous improvement in individuals suffering from medically unexplained symptoms (MUS) was explored of (1) anxiety and depression obtained from questionnaires, (2) negative affective states obtained from experience-sampling, and (3) ambulatory-assessed real-life physiological recordings. Sixty-seven individuals with MUS and 61 healthy controls were included. Twenty-four hour ambulatory recordings of cardiac autonomic activity, respiration, end-tidal CO(2) and saliva cortisol were combined with experience-sampling of somatic complaints and mood. Complaints were assessed again after one year. Although a reduction in symptoms (25%) was found, this could not be predicted from initial anxiety and depression. Improvement was somewhat related to relatively low diary reports of fatigue, especially in the late-afternoon and evening (3% variance explained). From the physiological measures only relatively high PetCO(2) values in the morning predicted improvement (5% explained). It was concluded that spontaneous recovery from MUS is hard to predict from self-reported distress and ambulatory physiological recordings.

It has been hypothesized that the ratio of heart rate variability in the low- (LF) and high- (HF) frequency bands may capture variation in cardiac sympathetic control. Here we tested the temporal stability of the LF/HF ratio in 24-h ambulatory recordings and compared this ratio to the preejection period (PEP), an established measure of cardiac sympathetic control. Good temporal stability was found across a period of 3.3 years (.46

Background: The Internet can facilitate diary monitoring (experience sampling, ecological momentary assessment) and behavioral coaching. Online digital assistance (ODA) is a generic tool for mobile Web-based use, intended as an adjuvant to face-to-face or Internet-based cognitive behavioral treatment based. A current ODA application was designed to support home-based training of behavioral attack prevention in chronic migraine, focusing on the identification of attack precursors and the support of preventive health behaviour., Objective: The aim was to establish feasibility of the ODA approach in terms of technical problems and participant compliance, and ODA acceptability on the basis of ratings of user-friendliness, potential burden, and perceived support of the training for behavioral attack prevention in migraine., Methods: ODA combines mobile electronic diary monitoring with direct human online coaching of health behavior according to the information from the diary. The diary contains three parts covering the following: (1) migraine headache and medication use, (2) attack precursors, and (3) self-relaxation and other preventive behavior; in addition, menstruation (assessed in the evening diary) and disturbed sleep (assessed in the morning diary) is monitored. The pilot study consisted of two runs conducted with a total of five women with chronic migraine without aura. ODA was tested for 8.5 days (range 4-12 days) per participant. The first test run with three participants tested 4-5 diary prompts per day. The second run with another three participants (including one subject who participated in both runs) tested a reduced prompting scheme (2-3 prompts per day) and minor adaptations to the diary. Online coaching was executed twice daily on workdays., Results: ODA feasibility was established on the basis of acceptable data loss (1.2% due to the personal digital assistant; 5.6% due to failing Internet transmission) and good participant compliance (86.8% in the second run). Run 1 revealed some annoyance with the number of prompts per day. Overall ODA acceptability was evident by the positive participant responses concerning user-friendliness, absence of burden, and perceived support of migraine attack prevention. The software was adapted to further increase the flexibility of the application., Conclusions: ODA is feasible and well accepted. Tolerability is a sensitive issue, and the balance between benefit and burden must be considered with care. ODA offers a generic tool to combine mobile coaching with diary monitoring,independently of time and space. ODA effects on improvement of migraine remain to be established.

It has been suggested that dysregulation of immune-to-brain communication plays a role in the biopsychological process underlying medically unexplained symptoms (MUS). Immune and non-immune stressors can both be involved in the activation of the central sickness-behavioural-system leading to complaints like malaise, pain and fatigue. We hypothesized increased pro-inflammatory and/or reduced anti-inflammatory cytokine activity to exist in MUS patients. Twenty-seven participants (4 male; 23 female) with heterogeneous MUS were compared with 27 healthy controls (6 male; 21 females). Blood samples were analysed for leukocyte subset cell counts, in vitro T-cell mitogen-stimulated cytokine production (IL-2, IL-4, IL-5, IL-6, IL-10, TNF-alpha and IFN-gamma) and in vitro monocyte cytokine release (IL-1beta, IL-6, IL-8, IL-10 and TNF-alpha) in response to increasing concentrations of LPS. No significant group differences were found for any of the cytokines measured. One unexpected exception was an elevation in the number of circulating B and NK-cells in participants high on MUS. Nonetheless, no support was found for the hypothesized immunological dysregulation in peripheral blood leukocyte function of MUS patients.

People with medically unexplained symptoms (MUS) often have a comorbid history of stress and negative affect. Although the verbal-cognitive and (peripheral) physiological stress systems have shown a great degree of independence, at the same time it is claimed that chronic stress and negative affect can result in a disregulated physiological stress system, which may lead to MUS. Previous studies could not demonstrate a straightforward between subject relationship between MUS and stress physiology, supporting the view of independence. The aim of the current study was to further explore this relationship using an improved methodology based on ecologically valid 24-h real-life ambulatory recordings. Seventy-four participants (19 male; 55 female) with heterogeneous MUS were compared with 71 healthy controls (26 male; 45 females). Momentary experienced somatic complaints and mood, heart rate, cardiac autonomic activity, respiration and saliva cortisol were monitored using electronic diary and ambulatory registration devices. Participants with MUS reported much more momentary complaints and negative affect as compared to controls. Although MUS seemed to be associated with elevated heart rate and reduced low and very-low frequency heart period variability, these effects disappeared after controlling for differences in sports behaviour. No group differences were found for cardiac autonomic activity, respiration, end-tidal CO(2) and saliva cortisol. Our 24-h real-life ambulatory study did not support the existence of a connection between MUS and disregulated peripheral stress physiology. Future studies may instead focus on central measures to reveal potential abnormalities such as deviant central processing of visceral signals in MUS patients.

The current study investigates the relationship between HPA-axis functioning and burnout symptoms by employing an electronic symptom diary. This diary method circumvents the retrospection bias induced by symptom questionnaires and allows to study relationships within-in addition to between-subjects. Forty two clinically burned-out participants completed the exhaustion subscale of the Maslach burnout inventory and kept an electronic diary for 2 weeks to assess momentary exhaustion and daily recovery through sleep. On 3 consecutive weekdays within the diary period, saliva was sampled to determine the cortisol awakening response (CAR), levels of dehydroepiandrosterone-sulphate (DHEAS) on the first 2 weekdays, and to conduct the dexamethasone suppression test (DST) on the third weekday. We found significant relationships between endocrine values and general momentary symptom severity as assessed with the diary, but not with the retrospective questionnaire-assessed burnout symptoms. Simultaneous assessments of endocrine values and burnout symptoms assessed with the diary after awakening rendered significant associations between persons, and a trend within persons. More severe burnout symptoms were consistently associated with a lower level and smaller increase of CAR, higher DHEAS levels, smaller cortisol/DHEAS ratios and a stronger suppression after DST. Burnout symptoms were significantly related to endocrine functioning in clinical burnout under the best possible conditions of symptom measurement. This adds support to the view that severity of burnout symptoms is associated with HPA-axis functioning.

Objective: When people report somatic complaints retrospectively, they depend on their memory. Therefore, retrospective reports can be influenced by general beliefs on sickness and health from semantic memory. We hypothesized that individuals with medically unexplained symptoms (MUS) would have recall biases stronger than those of people without complaints when reporting symptoms retrospectively, and that this effect would be a function of time between symptom experience and report., Methods: To compare two time frames, 37 participants who were high and low on MUS reported momentary symptoms combined by daily recall and weekly recall using an electronic diary., Results: Both groups reported more symptoms when recalling the entire week than what could be expected from average momentary reports. However, participants high on MUS also reported more symptoms when recalling a week than when recalling a day. For this group, recall bias was not associated with peak heuristic or symptoms variability., Conclusion: Symptom reports in people high on MUS increases as time passes by, probably as a results of a shift in memory retrieval strategy from using episodic knowledge to using semantic beliefs.

The extent to which various measures of ambulatory respiratory sinus arrhythmia (RSA) capture the same information across conditions in different subjects remains unclear. In this study the root mean square of successive differences (RMSSD), peak valley RSA (pvRSA), and high frequency power (HF power) were assessed during ambulatory recording in 84 subjects, of which 64 were retested after about 3 years. We used covariance structure modeling to test the equality of the correlations among three RSA measures over two test days and three conditions (daytime sitting or walking and nighttime sleep) and in groups with low, medium, and high mean heart rate (HR), or low, medium, and high mean respiration rate (RR). Results showed that ambulatory RMSSD, pvRSA, and HF power are highly correlated and that their correlation is stable across time, ambulatory conditions, and a wide range of resting HR and RR values. RMSSD appears to be the most cost-efficient measure of RSA.

The purpose of the current study was to validate the change in thoracic impedance (dZ) derived respiratory signal obtained from four spot electrodes against incidental spirometry. Additionally, a similar validation was performed for a dual respiratory belts signal to compare the relative merit of both methods. Participants were 38 healthy adult subjects (half male, half female). Cross-method comparisons were performed at three (paced) respiration frequencies in sitting, supine and standing postures. Multilevel regression was used to examine the within- and between-subjects structure of the relationship between spirometric volume and the respiratory amplitude signals obtained from either dZ or respiratory belts. Both dZ derived respiratory rate and dual belts derived respiratory rate accurately reflected the pacing frequencies. For both methods, fixed factors indicated acceptable but posture-specific regression on spirometric volume. However, random factors indicated large individual differences, which was supported by variability of gain analyses. It was concluded that both the dZ and dual belts methods can be used for measurement of respiratory rate and within-subjects, posture-specific, changes in respiratory volume. The need for frequent subject-specific and posture-specific calibration combined with relatively large measurement errors may strongly limit the usefulness of both methods to assess absolute tidal volume and minute ventilation in ambulatory designs.

The extent to which variation in posture and respiration can confound pre-ejection period and respiratory sinus arrhythmia (RSA) as indices of cardiac sympatho-vagal activity was examined. Within-subjects changes in these measures were assessed in 36 subjects during different postures and (paced) respiratory frequencies. Changes from supine to sitting to standing led to reduced RSA values and longer pre-ejection periods, reflecting the known decrease in vagal but not the increase of sympathetic activity. Multilevel path analysis showed that within-subjects changes in sympatho-vagal balance were faithfully reflected by changes in interbeat interval, but imperfectly by changes in RSA and pre-ejection period. It was concluded that pre-ejection period should be stratified for posture and RSA for respiratory frequency to reliably index changes in sympatho-vagal balance when these factors are prone to change (e.g., during 24-h ambulatory recording).

To investigate the role of the circadian pacemaker in autonomic modulation of base rate cardiac activity, 29 healthy subjects participated in a constant routine protocol. They were randomly divided into two groups in order to manipulate prior wakefulness. Group 1 started at 0900 hours immediately after a monitored sleep period, while group 2 started 12 h later. Measures of interbeat intervals (IBIs), respiratory sinus arrhythmia (RSA, an estimate of parasympathetic activity), pre-ejection period (PEP, an estimate of sympathetic activity), and core body temperature (CBT) were recorded continuously. Multilevel regression analyses (across-subjects) revealed significant 24- and/or 12-h sinusoidal circadian variation for CBT, IBI, and RSA, but not for PEP. Subject-specific 24+12 h sinusoidal fits demonstrated a convergence of phase distribution for IBI and RSA of group 1 similar to CBT, while PEP showed a relatively large (i.e. random) distribution of phase. In group 2, all cardiac measures showed large distributions of phase. Unexpected results in the cardiac measures were found in group 2, probably caused by group differences in prior activation. Also, effects of sleep deprivation were observed for IBI and RSA in group 2. Consequently, all cardiac measures revealed significant sinusoidal x group interactions, a result not shown in CBT. These findings were interpreted as an indication for circadian endogenous parasympathetic modulation of cardiac activity that is mainly confounded by prior wakefulness that extends 24 h, while the sympathetic modulation is relatively uncoupled from the endogenous circadian drive and mainly influenced by prior activation.

The hypothesis that biased symptom perception toward excessive symptoms is common when relatively normal chronic patients enter symptom-relating situations, irrespective of emotional variables, was tested in 19 women with severe asthma, 18 with somatization-like characteristics, and 18 controls. Each underwent three experimental conditions: mental stress, resting, and physical exercise. Each condition included three breathing conditions: breathing normally, normal compressed air, and 5.5% CO2-enriched compressed air. Results yielded no group differences in physiological measures, e.g. elevated CO2 in exhaled air (end-tidal partial pressure of CO2, PetCO2), or lung function. Asthma patients experienced more breathlessness, and somatization-like participants more breathlessness, miscellaneous symptoms, and subjective stress than controls. Although these differences suggested acquired biased symptom perception, as it turned out, breathlessness in asthmatics was more influenced by PetCO2 and less by subjective stress compared to controls. Likewise, breathlessness in somatization-like participants was similarly influenced by PetCO2 and subjective stress compared to controls, and miscellaneous symptoms were even more influenced by PetCO2 and less by subjective stress compared to controls. It was concluded that acquired sensitivity to physiological activity associated with habitual symptoms may account for excessive symptoms in patients with chronic health problems.

The role of endogenous circadian rhythmicity in autonomic cardiac reactivity to different stressors was investigated. A constant routine protocol was used with repeated exposure to a dual task and a cold pressor test. The 29 subjects were randomly divided into two groups in order to manipulate prior wakefulness. Group 1 started at 09:00 h immediately after a monitored sleep period, whereas group 2 started 12 h later. Measures of interbeat intervals (IBI), respiratory sinus arrythmia (RSA, a measure of parasympathetic activity), pre-ejection period (PEP, a measure of sympathetic activity), as well as core body temperature (CBT) were recorded continuously. Multilevel regression analyses (across-subjects) revealed significant (mainly 24 h) sinusoidal circadian variation in the response to both stressors for IBI and RSA, but not for PEP. Individual 24 + 12 h cosine fits demonstrated a relatively large interindividual variation of the phases of the IBI and RSA rhythms, as compared to that of the CBT rhythm. Sinusoidal by group interactions were found for IBI and PEP, but not for RSA. These findings were interpreted as an indication for endogenous circadian and exogenous parasympathetic (vagal) modulation of cardiac reactivity, while sympathetic reactivity is relatively unaffected by the endogenous circadian drive and mainly influenced by exogenous factors.

Objective: This study tested whether functional somatic symptoms are associated with exaggerated increases in self-reported anxiety and somatic complaints in response to stress and CO(2)-enriched air breathing, and whether this association exists in parallel to or in the absence of exaggerated physiological responses., Methods: Out of 499 young somatically healthy undergraduate women, 18 participants high in functional somatic symptoms (HSS group) and 18 participants low in symptoms (LSS) were selected. They were submitted to mental stress, mild physical exercise and relaxation during conditions of normal breathing, breathing compressed normal air, and breathing compressed 5% CO(2)-enriched air. In all conditions, self-reported anxiety and somatic symptoms and respiratory and autonomic responses were assessed., Results: HSS participants reported, as compared to LSS, more tenseness, anxiety, and somatic symptoms at baseline and increased responses to mental stress and during 5% CO(2) breathing, but not in response to exercise. However, no evidence was found for a corresponding exaggerated respiratory or autonomic response., Conclusions: A young, female, and nonclinical population with numerous functional somatic symptoms and high levels of anxiety is characterized by an exaggerated perception of a normal physiological response.

This study tested various sources of changes in respiratory sinus arrhythmia (RSA). Twenty-two healthy participants participated in three experimental conditions (mental stress, relaxation, and mild physical exercise) that each consisted of three breathing parts (normal breathing, breathing compressed room air, and breathing compressed 5% CO2-enriched air). Independent contributions to changes in RSA were found for changes in tonic vagal modulation of heart rate, central respiratory drive (i.e., PaCO2), respiratory depth, and respiratory frequency. The relative contributions to changes in RSA differed for mental stress and physical exercise. It is concluded that uncorrected RSA will suffice to index within-subject changes in tonic vagal modulation of heart rate in most situations. However, if the central respiratory drive is expected to change, RSA should ideally be corrected for changes in PaCO2, respiratory depth, and respiratory frequency.

Previous studies have demonstrated increased physiological-emotional responses despite relatively low self-reported affect for individuals with a repressive coping style, as compared to control groups. The main question in the current study was whether such group differences could also be demonstrated by using the picture perception methodology of Lang. A second question was whether differences between these groups could be found in the habituation of physiological and emotional responses. Repressors (n=14), 'truly' low anxious participants (n=14), and moderately high anxious participants (n=13) were selected with the Marlowe-Crowne Social Desirability Scale and the Taylor Manifest Anxiety Scale. Two sets of 27 pictures with alternating neutral, threatening and sexual content were presented whilst valence and arousal ratings, skin conductance, heart rate and facial muscle responses were measured. No straightforward group differences were found. However, the results suggest that differential habituation, and not a repressive coping style, may contribute to differential self-reported, facial and physiological-emotional responses.

The aim of this study was to assess the error made by violating the assumption of stationarity when using Fourier analysis for spectral decomposition of heart period power. A comparison was made between using Fourier and Wavelet analysis (the latter being a relatively new method without the assumption of stationarity). Both methods were compared separately for stationary and nonstationary segments. An ambulatory device was used to measure the heart period data of 40 young and healthy participants during a psychological stress task and during periods of rest. Surprisingly small differences (<1%) were found between the results of both methods, with differences being slightly larger for the nonstationary segments. It is concluded that both methods perform almost identically for computation of heart period power values. Thus, the Wavelet method is only superior for analyzing heart period data when additional analyses in the time-frequency domain are required.