Medically unexplained symptoms and between-group differences in 24-h ambulatory recording of stress physiology

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.

Psychobiological Mechanisms in Somatic Symptom Disorder and Depressive Disorders: An Ecological Momentary Assessment Approach

OBJECTIVE

Persistent somatic symptoms cause strong impairment in persons with somatic symptom disorder (SSD) and depressive disorders (DDs). Specific negative psychological factors (NPFs), such as catastrophizing, negative affectivity, and behavioral avoidance, are assumed to contribute to this impairment and may maintain symptoms via dysregulations of biological stress systems. We examined the associations between NPF and somatic symptoms in the daily life of women with SSD or DD and investigated the mediating role of psychobiological stress responses.

METHODS

Twenty-nine women with SSD and 29 women with DD participated in an ecological momentary assessment study. For 14 days, intensity of and impairment by somatic symptoms, NPF, and stress-related biological measures (cortisol, alpha-amylase) were assessed five times per day using an electronic device and saliva samples. Multilevel models were conducted.

RESULTS

The greater the number of NPF, the higher the concurrent and time-lagged intensity of and impairment by somatic symptoms in both groups (12.0%-38.6% of variance explained; χ2(12) p < .001 for all models). NPFs were associated with higher cortisol levels in women with DD and with lower levels in women with SSD (interaction NPF by group: B = -0.04, p = .042 for concurrent; B = -0.06, p = .019 for time-lagged). In women with SSD, lower cortisol levels were associated with higher intensity at the next measurement time point (group by cortisol: B = -1.71, p = .020). No mediation effects were found.

CONCLUSIONS

NPFs may be considered as transdiagnostic factors in the development and treatment of impairing somatic symptoms. Our findings will allow the development of new treatment strategies that use ecological momentary intervention approaches focusing on NPF.

Structural alterations in functional neurological disorder and related conditions: a software and hardware problem?

Functional neurological (conversion) disorder (FND) is a condition at the interface of neurology and psychiatry. A “software” vs. “hardware” analogy describes abnormal neurobiological mechanisms occurring in the context of intact macroscopic brain structure. While useful for explanatory and treatment models, this framework may require more nuanced considerations in the context of quantitative structural neuroimaging findings in FND. Moreover, high co-occurrence of FND and somatic symptom disorders (SSD) as defined in DSM-IV (somatization disorder, somatoform pain disorder, and undifferentiated somatoform disorder; referred to as SSD for brevity in this article) raises the possibility of a partially overlapping pathophysiology. In this systematic review, we use a transdiagnostic approach to review and appraise the structural neuroimaging literature in FND and SSD. While larger sample size studies are needed for definitive characterization, this article highlights that individuals with FND and SSD may exhibit sensorimotor, prefrontal, striatal-thalamic, paralimbic, and limbic structural alterations. The structural neuroimaging literature is contextualized within the neurobiology of stress-related neuroplasticity, gender differences, psychiatric comorbidities, and the greater spectrum of functional somatic disorders. Future directions that could accelerate the characterization of the pathophysiology of FND and DSM-5 SSD are outlined, including “disease staging” discussions to contextualize subgroups with or without structural changes. Emerging neuroimaging evidence suggests that some individuals with FND and SSD may have a “software” and “hardware” problem, although if structural alterations are present the neural mechanisms of functional disorders remain distinct from lesional neurological conditions. Furthermore, it remains unclear whether structural alterations relate to predisposing vulnerabilities or consequences of the disorder.

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Transdiagnostic systematic review of structural MRI studies in FND and SSD

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Sensorimotor-striatothalamic-limbic-paralimbic circuits implicated in both conditions.

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Some small sample size FND studies did not show group-level structural alterations.

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MRI alterations may relate to risk factors, compensatory changes or disease mechanisms.

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Early-phase discussion on disease-staging algorithms outlined as a future direction.

Symptoms and the body: Taking the inferential leap

The relationship between the conscious experience of physical symptoms and indicators of objective physiological dysfunction is highly variable and depends on characteristics of the person, the context and their interaction. This relationship often breaks down entirely in the case of "medically unexplained" or functional somatic symptoms, violating the basic assumption in medicine that physical symptoms have physiological causes. In this paper, we describe the prevailing theoretical approach to this problem and review the evidence pertaining to it. We then use the framework of predictive coding to propose a new and more comprehensive model of the body-symptom relationship that integrates existing concepts within a unifying framework that addresses many of the shortcomings of current theory. We describe the conditions under which a close correspondence between the experience of symptoms and objective physiology might be expected, and when they are likely to diverge. We conclude by exploring some theoretical and clinical implications of this new account.

Intragenerational social mobility and functional somatic symptoms in a northern Swedish context: analyses of diagonal reference models

BACKGROUND

Research indicate that social class mobility could be potentially important for health, but whether this is due to the movement itself or a result of people having been integrated in different class contexts is, to date, difficult to infer. In addition, although several theories suggest that transitions between classes in the social hierarchy can be stressful experiences, few studies have empirically examined whether such movements may have health effects, over and above the implications of "being" in these classes. In an attempt to investigate whether intragenerational social mobility is associated with functional somatic symptoms in mid-adulthood, the current study tests three partially contrasting theories.

METHOD

The dissociative theory suggests that mobility in general and upward mobility in particular may be linked to psychological distress, while the falling from grace theory indicates that downward mobility is especially stressful. In contrast, the acculturation theory holds that the health implications of social mobility is not due to the movement itself but attributed to the class contexts in which people find themselves. Diagonal Reference Models were used on a sample of 924 individuals who in 1981 graduated from 9^th grade in the municipality of Luleå, Sweden. Social mobility was operationalized as change in occupational class between age 30 and 42 (measured in 1995 and 2007). The health outcome was functional somatic symptoms at age 42, defined as a clustering self-reported physical symptoms, palpitation and sleeping difficulties during the last 12 months.

RESULTS

Overall mobility was not associated with higher levels of functional somatic symptoms compared to being immobile (p = 0.653). After controlling for prior and current class, sex, parental social position, general health, civil status, education and unemployment, the association between downward mobility was borderline significant (p = 0.055) while upward mobility was associated with lower levels of functional somatic symptoms (p = 0.03).

CONCLUSION

The current study did not find unanimous support for any of the theories. Nevertheless, it sheds light on the possibility that upward mobility may be beneficial to reduce stress-related health problems in mid-life over and above the exposure to prior and current class, while downward mobility can be of less importance for middle-age health complaints.

Are Cardiac Autonomic Nervous System Activity and Perceived Stress Related to Functional Somatic Symptoms in Adolescents? The TRAILS Study

Objective

Stressors have been related to medically insufficiently explained or functional somatic symptoms (FSS). However, the underlying mechanism of this association is largely unclear. In the current study, we examined whether FSS are associated with different perceived stress and cardiac autonomic nervous system (ANS) levels during a standardized stressful situation, and whether these associations are symptom-specific.

Methods

We examined 715 adolescents (16.1 years, 51.3% girls) from the Dutch cohort study Tracking Adolescents’ Individual Lives Sample during the Groningen Social Stress Test (GSST). FSS were assessed by the Youth Self-Report, and clustered into a cluster of overtiredness, dizziness and musculoskeletal pain and a cluster of headache and gastrointestinal symptoms. Perceived stress levels (i.e. unpleasantness and arousal) were assessed by the Self-Assessment Manikin, and cardiac ANS activity by assessing heart rate variability (HRV-HF) and pre-ejection period (PEP). Perceived stress and cardiac ANS levels before, during, and after the GSST were studied as well as cardiac ANS reactivity. Linear regression analyses were used to examine the associations.

Results

Perceived arousal levels during (beta = 0.09, p = 0.04) and after (beta = 0.07, p = 0.047) the GSST, and perceived unpleasantness levels before (beta = 0.07, p = 0.048) and during (beta = 0.12, p = 0.001) the GSST were related to FSS during the past couple of months. The association between perceived stress and FSS was stronger for the FSS cluster of overtiredness, dizziness and musculoskeletal pain than for the cluster of headache and gastrointestinal symptoms. Neither ANS activity levels before, during, and after the GSST, nor maximal HF-HRV and PEP reactivity were related to FSS.

Conclusions

This study suggests that perceived stress levels during social stress are related to FSS, whereas cardiac ANS activity and reactivity are not related to FSS.

Psychophysiological Assessment of Stress Under Ecological Settings

Abstract. Stress can negatively impact one’s health and well-being, however, despite the recent evolution in stress assessment research methodologies, there is still little agreement about stress conceptualization and assessment. In an attempt to summarize and reflect on this evolution, this paper aims to systematically review research evidence of ecological approaches on psychophysiological stress assessment. Thus, a literature search of electronic databases was conducted spanning 22 years (1990–2012) and 55 studies were reviewed. Studies were considered for inclusion if they contemplated both psychological and physiological measures of stress under ecological settings. This review focuses on five themes: methodology terminology, research population, study design, measurement, and technology. Findings support the need to use a common methodology terminology in order to increase scientific rigor. Additionally, there seems to be an increasing tendency for the use of these methods by multidisciplinary teams among both clinical and nonclinical populations aiming to understand the relationship between stress and disease. Most of the studies reviewed contemplated a time-based protocol and different conceptualizations of stress were found, resulting in the use of different subjective measures. Findings reinforce the importance of combining subjective and objective measures while also controlling for possible time- or situation-dependent confounders’. Advances in technology were evident and different assessment techniques were found. The benefits and challenges of ecological protocols to assess stress are discussed and recommendations for future research are provided, aiming to overcome previous limitations and advance scientific knowledge in the area.

Design of an ecological momentary assessment study of exposure to radiofrequency electromagnetic fields and non-specific physical symptoms

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.

Inducing symptoms in high symptom reporters via emotional pictures: the interactive effects of valence and arousal

OBJECTIVE

Processing unpleasant emotional cues induces elevated reporting of physical symptoms, especially in people with high habitual symptom reporting. The present study examined the role of valence and arousal of emotional pictorial cues on this effect.

METHODS

Female participants (N=45; 21 high/24 low habitual symptom reporters) viewed six series of emotional pictures with a homogeneous affective content: low arousal/positive, high arousal/positive, low arousal/negative, high arousal/negative-disgust, high arousal/negative-threat and neutral. Heart rate (HR) and skin conductance level (SCL) were recorded during picture viewing and a symptom checklist and valence and arousal ratings were completed after each trial.

RESULTS

High habitual symptom reporters reported more symptoms than low habitual symptom reporters overall, but this difference was more pronounced when processing unpleasant high arousing cues. No group differences were found on physiological measures for any of the conditions, while perceived valence and arousal both moderated the relationship between habitual symptom reporting and symptom induction.

CONCLUSION

These findings show an interactive effect of unpleasantness and high arousal on elevated symptom reporting in high habitual symptom reporters, suggesting that different characteristics of emotional cues contribute to a somatic memory activation process leading to the experience of elevated symptoms.

Associations between mental disorders and the common cold in adults: a population-based cross-sectional study

OBJECTIVE

To investigate the association between specific mental disorders and the common cold.

METHODS

Negative binomial regression analyses were applied to examine cross-sectional associations of a broad range of mental disorders according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) employing the standardized Munich Composite International Diagnostic Interview, with the self-reported number of occurrences of the common cold during the past 12 months in a representative population sample of 4022 German adults aged 18-65 years.

RESULTS

After adjustment for covariates including age, gender, and marital and socioeconomic status, having any 12-month DSM-IV mental disorder (incidence rate ratio [IRR]=1.44, 95% confidence interval [CI]=1.29-1.60), any substance abuse or dependence (IRR=1.32, 95% CI=1.14-1.52), possible psychotic disorder (IRR=1.43, 95% CI=1.09-1.87), any mood disorder (IRR=1.35, 95% CI=1.16-1.56), any anxiety disorder (IRR=1.40, 95% CI=1.23-1.59), or any somatoform disorder (IRR=1.38, 95% CI=1.18-1.62) was shown to be positively associated with the number of occurrences of a cold during the past 12 months.

CONCLUSION

The presence of a DSM-IV mental disorder was associated with a 44% higher risk of having experienced a cold in the past 12 months. Further studies are needed to explore potential common risk factors for incidence of mental disorders and the common cold, since the pathway connecting them has not been fully determined.

Food Deprivation Sensitizes Pain Perception

While food deprivation has known effects on sympathovagal balance, little is known about hunger’s influence on the perception of pain. Since autonomic activities influence many cognitive and emotional processes, this suggests that food deprivation should interact with the perception of pain. This study analyzed the possible effects of short-term food deprivation on pain sensitivity in healthy female participants. This study was comprised of 32 healthy female participants who underwent a 48-hr inpatient hospital investigation. Prior to testing, heart rate and heart rate variability were assessed. After a standardized breakfast, day 1 measurements were taken. Food intake was then not allowed again until the following evening for 22 participants (experimental group), while 12 participants were served standard meals (control group). Pain threshold and tolerance were assessed at 10:00 a.m. on both days using a pressure algometer. Additionally pain experience was examined. Food deprivation significantly reduced pain thresholds and tolerance scores in the experimental group. Additionally, the sympathovagal balance changed, characterized by a decrease in parasympathetic activation. Higher vagal withdrawal after food deprivation was associated with higher pain sensitivity in the experimental group. Furthermore, perceived unpleasantness and pain intensity increased for threshold and tolerance stimuli in the experimental group. We conclude that short-term food deprivation sensitized pain perception in healthy females. An imbalance in sympathovagal activation evoked by food deprivation accounted for this effect. Our results might be a pathogenic mechanism for the development of emotional difficulties associated with disturbed eating behavior.

Autonomic imbalance is associated with reduced facial recognition in somatoform disorders

OBJECTIVES

Somatoform disorders are characterized by the presence of multiple somatic symptoms. While the accuracy of perceiving bodily signal (interoceptive awareness) is only sparely investigated in somatoform disorders, recent research has associated autonomic imbalance with cognitive and emotional difficulties in stress-related diseases. This study aimed to investigate how sympathovagal reactivity interacts with performance in recognizing emotions in faces (facial recognition task).

METHODS

Using a facial recognition and appraisal task, skin conductance levels (SCLs), heart rate (HR) and heart rate variability (HRV) were assessed in 26 somatoform patients and compared to healthy controls. Interoceptive awareness was assessed by a heartbeat detection task.

RESULTS

We found evidence for a sympathovagal imbalance in somatoform disorders characterized by low parasympathetic reactivity during emotional tasks and increased sympathetic activation during baseline. Somatoform patients exhibited a reduced recognition performance for neutral and sad emotional expressions only. Possible confounding variables such as alexithymia, anxiety or depression were taken into account. Interoceptive awareness was reduced in somatoform patients.

CONCLUSIONS

Our data demonstrate an imbalance in sympathovagal activation in somatoform disorders associated with decreased parasympathetic activation. This might account for difficulties in processing of sad and neutral facial expressions in somatoform patients which might be a pathogenic mechanism for increased everyday vulnerability.

Blunted autonomic reactivity and increased pain tolerance in somatoform patients

Somatoform disorders are characterized by the presence of multiple somatic symptoms. Patients often experience different pain syndromes, and recent research suggests that sympathovagal balance is disturbed in somatoform patients, which could be related to alteration in pain sensitivity. This study analyzed how proposed sympathovagal imbalance interacts with objective pain assessment and the imagination of pain in somatoform disorders. Twenty-one patients (4 men) with diagnosed multisomatoform disorder were included in the study and matched to healthy control subjects. Autonomic measures and heart rate variability were assessed during baseline; pain perception was assessed by means of a pressure algometer and pain imagination. We found evidence for a sympathovagal imbalance in somatoform disorders characterized by low parasympathetic activation and high sympathetic activation during all conditions. Additionally, somatoform patients had reduced pain tolerance. Vagal withdrawal during pain assessment was more pronounced for healthy control subjects and correlated positively with assessed pain tolerance. During imagination somatoform, patients reported higher pain unpleasantness and higher pain intensity as compared to control subjects. We conclude that our data demonstrate an imbalance in sympathovagal activation and a hyposensitivity to pain tolerance stimuli in somatoform disorders. Parasympathetic reactivity might form crucial information when judging pain-associated affective-motivational components. Our results might be attributable to a deficient detection of visceral signals and might be a pathogenetic mechanism for the development of emotional difficulties and increased everyday vulnerability in somatoform patients.

Deviations in the endocrine system and brain of patients with fibromyalgia: cause or consequence of pain and associated features?

The brain and endocrine system are crucial interfaces responding to pathological and psychological processes. This review discusses whether endocrine deviations and structural and functional changes in the brain are a cause or consequence of fibromyalgia. Studies in patients with fibromyalgia virtually uniformly observed subtle alterations in hypothalamic pituitary adrenal functioning, hyporeactive autonomic nervous system responsiveness to stressors, and structural and functional changes in the brain. Our model proposes that predisposing factors, such as genetic vulnerability and trauma, have led to an alteration of the nociceptive system including several neuroendocrine changes. The resulting pain and associated symptoms, such as sleep disturbance, low fitness, fatigue, stress, and distress, are a cause of new neuroendocrine changes. The model predicts that favorable neuroendocrine changes are to be expected after successful pharmacological or non-pharmacological interventions that target pain and associated symptoms.

Emotional disorders: cluster 4 of the proposed meta-structure for DSM-V and ICD-11

BACKGROUND

The extant major psychiatric classifications DSM-IV, and ICD-10, are atheoretical and largely descriptive. Although this achieves good reliability, the validity of a medical diagnosis would be greatly enhanced by an understanding of risk factors and clinical manifestations. In an effort to group mental disorders on the basis of aetiology, five clusters have been proposed. This paper considers the validity of the fourth cluster, emotional disorders, within that proposal.

METHOD

We reviewed the literature in relation to 11 validating criteria proposed by a Study Group of the DSM-V Task Force, as applied to the cluster of emotional disorders.

RESULTS

An emotional cluster of disorders identified using the 11 validators is feasible. Negative affectivity is the defining feature of the emotional cluster. Although there are differences between disorders in the remaining validating criteria, there are similarities that support the feasibility of an emotional cluster. Strong intra-cluster co-morbidity may reflect the action of common risk factors and also shared higher-order symptom dimensions in these emotional disorders.

CONCLUSION

Emotional disorders meet many of the salient criteria proposed by the Study Group of the DSM-V Task Force to suggest a classification cluster.

Dysfunction of the hypothalamic-pituitary-adrenal axis and functional somatic symptoms: a longitudinal cohort study in the general population

In persons with functional somatic symptoms (FSS), no conventionally defined organic pathology is apparent. It has been suggested that complex interactions of psychological, physiological, and social factors are involved in the etiology of FSS. One of the physiological mechanisms that may contribute to FSS is the function of the hypothalamic-pituitary-adrenal (HPA)-axis. This study investigates the association of HPA-axis function with cross-sectional presence and prospective development of FSS in the general population. This study was performed in a population-based cohort of 741 male and female adults (mean age 53.1, S.D. 10.9). Participants completed the somatization section of the Composite International Diagnostic Interview (CIDI) in which the presence of 43 FSS is surveyed. In addition to the total number of FSS, bodily system FSS clusters with musculoskeletal, gastrointestinal, cardiorespiratory, and general symptoms were constructed. HPA-axis function was assessed by measuring 24-h urinary free cortisol (24-h UFC) excretion. Follow-up measurements were performed approximately 2 years later. All analyses were adjusted for age, gender, body mass index, smoking, alcohol use, depression, exercise frequency, and urinary volume. Regression analysis detected no cross-sectional association between 24-h UFC excretion and the number of FSS (beta=-0.021, t=-0.521, p=0.603). In addition, 24-h UFC excretion was not associated with any of the bodily system FSS clusters (all p>0.050). Furthermore, 24-h UFC excretion did not predict new-onset FSS in the 2-year follow-up period (beta=0.021, t=0.566, p=0.572). We conclude that this study does not provide evidence for an association between altered HPA-axis function, as indexed by 24-h UFC, and FSS in the general population. We conclude that this study does not provide evidence for an association between altered HPA-axis function, as indexed by 24-h UFC, and FSS in the general population.

Noninvasive Psychophysiological Ambulatory Recordings

Rapid technical developments have greatly facilitated noninvasive 24-hour recording of physiological signals at relatively low costs, including blood pressure, activity of the autonomic nervous system, respiratory behavior, and activity of the hypothalamic-pituitary-adrenocortical axis. Ambulatory noninvasive recordings can be used to study the baseline levels of these physiological variables as well as their reactivity to naturalistic stressors. Levels and reactivity can be compared across groups differing in exposure to risk factors (e.g., stress, genotypes) or used to sharpen the clinical profile of individual subjects (e.g., in panic or somatoform disorders). The focus of the current paper is on the importance of a priori choices in study design and data analysis strategies when ambulatory recording specifically targets the reciprocal relationship between physiological and psychological events. These choices are illustrated with ambulatory-assessed indices of the cardiac autonomic nervous system, blood pressure, respiration, and cortisol secretion.

High symptom reporters are less interoceptively accurate in a symptom-related context

OBJECTIVE

We investigated the role of a symptom interpretation frame on the accuracy of interoception and on retrospective symptom reporting in nonclinical high and low reporters of medically unexplained symptoms.

METHODS

All participants (N=74) went through two subsequent trials of the Rebreathing Test, inducing altered respiration and other physical sensations as a result of a gradually increasing pCO(2) level in the blood. Each trial consisted of a baseline (60 s), a rebreathing phase (150 s), and a recovery phase (150 s). In one trial, the sensations were framed in a neutral way ("the gas mixture might alter breathing behavior and induce respiratory sensations"). In the other trial, a symptom frame was induced ("the gas mixture might alter breathing behavior and induce respiratory symptoms"). Breathing behavior was continuously monitored, subjective sensations were rated every 10 s, and after each trial, participants filled out a symptom checklist. Within-subject correlations between the subjective rating and its physiological referent were calculated for the rebreathing phase and recovery phase of each trial separately.

RESULTS

High symptom reporters had more (retrospective) complaints than low symptom reporters, especially in the symptom trial. Only in the symptom frame were high symptom reporters less accurate than low symptom reporters. The reduction in interoceptive accuracy (IA) in high symptom reporters was most striking in the recovery phase of the symptom frame trial.

CONCLUSION

A contextual cue, such as a reference to symptoms, reduced IA in high symptom reporters and this was more so during recovery from the symptom induction.

Salivary cortisol, stress and mood in healthy older adults: the Zenith study

The aims of this study were to investigate the relationship between salivary cortisol, stress and mood and to look at the circadian rhythms of positive (PA) and negative (NA) mood in older adults. The participants were 41 healthy adults aged 55-69 years, recruited in Northern Ireland as part of the European Commission-funded Zenith project. Salivary cortisol samples were obtained twice a day (2.30 p.m. and 10.30 p.m.) for 7 consecutive days in conjunction with momentary measures of positive (PA) and negative mood (NA), using PANAS and a trait measure of perceived stress (Perceived Stress Scale). Salivary cortisol levels were measured using an enzyme-linked immunoassay kit. Higher perceived stress levels were associated with lower afternoon PA (r=-0.46, p=0.003) and higher afternoon (r=0.43, p=0.007) and evening (r=0.45, p=0.004) NA. Lower afternoon PA was correlated with higher evening cortisol concentrations (r=-0.47, p=0.002). Greater afternoon PA variability was associated with higher evening cortisol concentrations (r=0.38, p=0.015). A high intra-class correlation between cortisol and positive mood was found (r=0.67, p=0.009). Previously established rhythms for positive and negative mood were confirmed. Interestingly, there was no association between salivary cortisol levels and perceived stress in these healthy older adults. Further, more extensive research is required to better understand the apparent interplay between these variables and ageing.