Mental Arithmetic Stress Task Research Articles

Testing adverse childhood experiences (ACEs) as a potential moderator of the association between current chronic stress and cardiovascular reactivity

Motivated by mixed findings regarding the relationship between chronic stress and cardiovascular reactivity, the current study aimed to investigate whether adverse childhood experiences (ACEs) serve as a potential moderator of the association between current chronic stress and cardiovascular reactivity. Incidence of ACEs, levels of current chronic stress, and heart rate (HR) reactivity to a mental arithmetic stress task were measured in 111 participants (age = 20.83, 76 % female, 66 % White). ACEs were measured using the Childhood Trauma Questionnaire and current chronic stress was measured using the Perceived Stress Scale. Moderation analyses were conducted with HR reactivity as the outcome and ACEs as the moderator. Results indicated that a greater amount of current chronic stress was significantly associated with relatively blunted HR reactivity (β = −0.25, p = 0.03) even after controlling for sociodemographic variables. Exposure to ACEs was not significantly related to HR reactivity, (all p ≥ 0.66), and there was no significant interaction between current chronic stress and ACE exposure in predicting HR reactivity, (all p ≥ 0.44). These results show that current chronic stress is associated with relatively blunted HR reactivity and that exposure to ACEs does not moderate the relationship between chronic stress and cardiac stress reactivity.

Muscle Tension in Generalized Anxiety Disorder During a Stressful Mental Arithmetic Task

Introduction: The purpose of this study was to compare muscle tension between individuals with and without generalized anxiety disorder (GAD) during a resting state and a stressful mental arithmetic task. Methods: A total of 95 undergraduate students (68 females and 27 males; mean age=19.6, SD=3.5) completed an online survey on GAD symptoms and pathological worry, a diagnostic interview, and two laboratory tasks (resting and mental arithmetic tasks) while electromyography (EMG) signals were being recorded. Results: We found a significant main effect of condition, F(1,93) = 24.13, p<.001, and group, F(1,93) = 4.55, p=.036. Furthermore, there was a significant interaction effect between condition and group, F(1,93) = 5.85, p=.017. A post-hoc analysis revealed that the increase in EMG activity from the resting period, 95% CI [.002398 .003474], to the mental arithmetic task, 95% CI [.003850 .005086], was significant for the GAD group, but not for the non-GAD group. Conclusions: Individuals with and without GAD did not show significant differences in physiologically measured muscle tension at baseline. However, the GAD group showed higher levels of muscle tension during stressful situations when compared to the non-GAD group.

Effect of Positive Mental Imagery Stimuli on Anhedonic Depressive Symptoms

This study aimed to investigate the effect of the intervention of positive mental imagery on anhedonia and the underlying reward mechanism in depression, and to explore the sustainability of the impact of the intervention following stress induction. Participants reporting anhedonic depressive symptoms (N=54) were randomly assigned to either a positive mental imagery condition or a verbalization condition, the former utilizing positive imagery stimuli only, and the latter utilizing language-based on meaning. Participants in both the conditions completed a computerized picture-word task for imagery generation and mental arithmetic stress task for stress induction. The results showed that both intervention conditions significantly reduced anhedonia and negative affect and that the mental imagery intervention was not superior to verbalization intervention. After stress induction, there was no significant difference between the two conditions in terms of the sustainability of the impact of the intervention on mood, reward subcomponents, and anhedonia. These findings provide preliminary evidence of the effectiveness of positive mental imagery in improving anhedonia. Furthermore, this study emphasizes the importance of repetitive imagery intervention due to the unsustainable impact of brief interventions after stress induction.

Effect of short-term mental stress on time- domain indices of heart rate variability in obese individuals – A case- control study


 Introduction and Aim: Mental stress may impact dramatically on dynamic autonomic control on heart. Many studies have demonstrated association of high body mass index (BMI) with greater risk for cardiovascular disease with disturbance in autonomic neuronal activity. Analysis of Heart rate variability (HRV)during acute mental stress assesses the autonomic status of the individual. Hence, we aimed to study the effect of acute mental stress on time domain measures in obese adults.
 
 Materials and Methods:Sixty male volunteers of 30 each in study group (obese individuals) and control group (non-obese individuals) were recruited for the study. A basal recording of ECG in lead II was done on all the individuals. Then they underwent mental arithmetic stress task for 5 minutes during which again ECG was recorded. The change in time domain measures of HRV during rest and stress task was analyzed and compared between both the groups.
 
 Results: Analysis of time domain measures of HRV revealed a statistically significant increase (p ? 0.001) in mean heart rate in both obese and non-obese individuals, while rMSSD(root mean square differences of successive RR interval) and SDNN (standard deviation of all NN intervals) showed a statistically significant (p? 0.001) decrease in obese individuals and non-obese individuals did not show any statistically significant change during the mental stress task.
 
 Conclusion: In response to acute mental stress there was increased heart rate in both the groups. But the autonomic neuronal activity differed by way of sympathetic dominance in non-obese individuals and parasympathetic withdrawal in obese individuals.

0162 Mental Stress Compromises Human Sleep Through a Biological, Not Psychological, Pathway

Abstract Introduction The extent to which mental stress causes sleep disturbance is unknown as experimental studies of stress and sleep have yielded mixed results. Potential mechanisms linking stress to poor sleep are also poorly characterized. The current study aimed to 1) assess the impact of experimentally-induced mental stress on daytime sleep and 2) test candidate mechanisms including physiological and emotional stress reactivity, stress rumination, attentional threat bias, and insensitivity to future consequences. Methods Participants (N=30) were randomized to a control (n=14) or stress group (n=16). Both groups were given a 60-minute nap opportunity at midday (≈13:30). Prior to sleep, participants in the stress group completed a socially evaluative mental arithmetic stress task and were instructed that they would be required to give a brief speech upon awakening. Sleep was monitored with polysomnography and scored according to standard AASM criteria. Measures of heart rate (HR), blood pressure (BP) and self-reported stress were recorded during the stress task. Self-reported stress rumination was measured upon awakening. Attentional threat bias was measured using an emotional dot probe and performance on the Iowa Gambling Task quantified insensitivity to future consequences. Results Acute mental stress significantly increased HR and BP (all p<.001, all Cohen’s d>1.24) and participants reported significant increases in self-reported stress (p<.001). The stress group exhibited longer sleep latency (p=.038, d=.82), shorter sleep duration (p=.044, d=.78), and worse sleep continuity (p=.045, d=.79). Subjective sleep quality was not different across groups (p=.39, d=.32). Of all candidate mechanisms, physiological reactivity was the only one significantly related to sleep measures. Greater HR reactivity predicted longer sleep latency (r=.37), shorter sleep duration (r=-.59), and worse sleep continuity (r=-.59). Conclusion Acute mental stress caused significant disturbances in a single episode of daytime sleep. The degree of disturbance was, to an extent, predicted by the amount of physiological reactivity to stress. Support This work was supported a Washington and Lee University Summer Lenfest Grant and the Summer Research Scholars Program.

Exploring How Trait Mindfulness Relates to Perceived Stress and Cardiovascular Reactivity.

Mindfulness interventions have been associated with less global perceived stress as well as attenuated cardiovascular reactivity. The aim of the present study was to evaluate whether high levels of trait mindfulness would also be associated with these benefits. Participants were 99 healthy young adults aged 18-25years. Self-report measures included the Five Facet Mindfulness Questionnaire and the Perceived Stress Scale. Participants completed a laboratory stress protocol comprised of a resting baseline, a mental arithmetic stress task, and a resting recovery period. Blood pressure, heart rate, and heart rate variability were measured throughout the protocol. Regressions were used to analyze whether trait mindfulness predicted global perceived stress, cardiovascular reactivity, and cardiovascular recovery. Two trait mindfulness facets were found to be associated with less global perceived stress, Acting with Awareness (β= - .306, p= .002) and Nonjudgment (β= - .342, p< .001). Exploratory analyses also revealed an interaction between the Observe and Nonreactivity facets (p= .002), such that the Observe facet was associated with less stress only when Nonreactivity scores were also high. Although trait mindfulness was not a significant predictor of the physiological variables (p> .05, Cohen's f2< .060), exploratory analyses revealed an interaction between the Awareness and Nonjudgment facets (p< .001), such that Awareness is associated with lower diastolic blood pressure reactivity only when Nonjudgment scores are also high. Like mindfulness interventions, trait mindfulness is associated with less global perceived stress. Interactions between trait mindfulness facets that reflect attention monitoring and acceptance might predict physiological reactivity in certain contexts, though a mindful state might be necessary for most real-time cardiovascular benefits.

Cardiac autonomic modulation in response to stress in normotensive young adults with parental history of hypertension.

Background Hypertension is the major health burden associated with increased cardiovascular morbidity and mortality. Positive family history and stress are the risk factors for hypertension. The present study aims to evaluate the effect of acute stress on the cardiac autonomic modulation in normotensive individuals with parental history of hypertension. Methods Sixty healthy male volunteers (30 with parental history of hypertension-NTPH+ group and 30 without parental history of hypertension-NTPH- group) in the age group of 18-24 years were included in the study. Short-term baseline heart rate variability (HRV) evaluation was done in frequency domain. Volunteers performed mental arithmetic stress task (MAST). HRV was measured before MAST, during MAST, and recovery period. HRV in both groups were compared. Results Analysis showed a significant increase in heart rate (p-value = 0.038) and systolic blood pressure (p-value = 0.01) in NTPH+ group compared to the NTPH- during MAST. NTPH+ group showed significantly higher LFnu (p-value = 0.03) and LF/HF ratio (p-value = 0.02) during MAST. Reduction in HFnu (p-value = 0.027) was significantly higher in the study group. ANOVA analysis demonstrated significant increase in LFnu [F(2.602, 75.46) = 18.60; p < 0.001; ηp2 = 0.391] and LF/HF ratio [F(1.76, 51.043) = 29.952; p < 0.001; ηp2 = 0.508] during MAST and 10 min of recovery period from baseline value in NTPH+ group. HFnu has significantly reduced during MAST and 5 min recovery period from baseline value in NTPH+ group [F(2.78, 80.72) = 12.77; p = 0.033, ηp2 = 0.28]. Conclusions Acute mental stress leads to exaggerated sympathetic response and vagal suppression in healthy individuals with parental history of HTN. This study concludes that HRV, which reflects autonomic flexibility, is lower during acute mental stress and post-stress recovery period in normotensive males with parental history of HTN.

Higher levels of Depressive Symptoms are Associated with Increased Resting-State Heart Rate Variability and Blunted Reactivity to a Laboratory Stress Task among Healthy Adults.

Laboratory stress tasks induce strong changes in linear and non-linear indices of heart rate variability (HRV) among healthy adults, due to a task-induced parasympathetic withdrawal. Previous findings suggested that negative affectivity and its correlates (i.e., depressive symptoms, anxiety, hostility, type D personality, and situational stress) could profoundly affect autonomic activity. However, to date no studies considered these psychological dimensions simultaneously while trying to disentangle their acute effects on HRV during a laboratory stress task. A total of 65 healthy participants completed a battery of questionnaires and later underwent a psychosocial stress protocol, which involves a stressful and a non-stressful mental arithmetic task, with the latter serving as a control condition for the former. During the entire procedure, autonomic activity was recorded through a portable ECG device. We analysed longitudinal changes in HRV indices using Mixed Models, taking into account respiration rates and the associations between psychophysiological variables through bivariate Pearson's r (partial) correlation indices. We found significant changes in linear (e.g., HF power, RMSSD) and non-linear (e.g., Poincaré Plot and Correlation Dimension D2) HRV indices during the procedure, with the lowest point reached during the stressful mental arithmetic task. Interestingly, only depressive symptomatology was significantly and positively related to a higher resting-state HRV and to a blunted reactivity to the stress task, even after controlling for baseline values. Results suggest that healthy individuals with higher levels of depressive symptoms could experience atypical cardiovascular responses to stressful events: several speculative interpretations, considering autonomic, behavioral, and motivational dysregulations, are discussed.

Acute hydrocortisone administration reduces cardiovagal baroreflex sensitivity and heart rate variability in young men.

Key points A surge in cortisol during acute physiological and pathophysiological stress may precipitate ventricular arrhythmia and myocardial infarction.Reduced cardiovagal baroreflex sensitivity and heart rate variability are observed during acute stress and are associated with an increased risk of acute cardiac events.In the present study, healthy young men received either a single iv bolus of saline (placebo) or hydrocortisone, 1 week apart, in accordance with a randomized, placebo‐controlled, cross‐over study design.Hydrocortisone acutely increased heart rate and blood pressure and reduced cardiovagal baroreflex sensitivity and heart rate variability in young men.These findings suggest that, by reducing cardiovagal baroreflex sensitivity and heart rate variability, acute surges in cortisol facilitate a pro‐arrhythmic milieu and provide an important mechanistic link between stress and acute cardiac events Surges in cortisol concentration during acute stress may increase cardiovascular risk. To better understand the interactions between cortisol and the autonomic nervous system, we determined the acute effects of hydrocortisone administration on cardiovagal baroreflex sensitivity (BRS), heart rate variability (HRV) and cardiovascular reactivity. In a randomized, placebo‐controlled, single‐blinded cross‐over study, 10 healthy males received either a single iv bolus of saline (placebo) or 200 mg of hydrocortisone, 1 week apart. Heart rate (HR), blood pressure (BP) and limb blood flow were monitored 3 h later, at rest and during the sequential infusion of sodium nitroprusside and phenylephrine (modified Oxford Technique), a cold pressor test and a mental arithmetic stress task. HRV was assessed using the square root of the mean of the sum of the squares of differences between successive R‐R intervals (rMSSD). Hydrocortisone markedly increased serum cortisol 3 h following infusion and also compared to placebo. In addition, hydrocortisone elevated resting HR (+7 ± 4 beats min−1; P < 0.001) and systolic BP (+5 ± 5 mmHg; P = 0.008); lowered cardiovagal BRS [geometric mean (95% confidence interval) 15.6 (11.1–22.1) ms/mmHg vs. 26.2 (17.4––39.5) ms/mmHg, P = 0.011] and HRV (rMSSD 59 ± 29 ms vs. 84 ± 38 ms, P = 0.004) and increased leg vasoconstrictor responses to cold pressor test (Δ leg vascular conductance −45 ± 20% vs. −23 ± 26%; P = 0.023). In young men, an acute cortisol surge is accompanied by increases in HR and BP, as well as reductions in cardiovagal BRS and HRV, potentially providing a pro‐arrhythmic milieu that may precipitate ventricular arrhythmia or myocardial infarction and increase cardiovascular risk.

Heart rate and high frequency heart rate variability during stress as biomarker for clinical depression. A systematic review.

The interaction of physical and mental vulnerability and environmental constraints is thought to foster the development of psychiatric disorders such as major depressive disorder (MDD). A central factor in the development of psychopathology is mental stress. Despite some evidence for parasympathetic withdrawal and sympathetic overactivity in MDD, the psychophysiological response to stress in depression is not clear-cut. Given the growing interest in heart rate and heart rate variability as indicators for remote monitoring of patients, it is important to understand how patients with MDD react to stress in a laboratory-controlled environment. We conducted a systematic review of studies using electrocardiography to derive heart rate and heart rate variability during stress in patients with clinical depression. We focused on well-validated stress tasks- the mental arithmetic stress task, the Trier social stress task and public speaking task- to minimize confounding effects due to the nature of the stressor. The majority of studies found hypo-reactivity during stress as a hallmark of depression as evidenced by lower fluctuation in heart rate and heart rate variability in the high-frequency band. We address the potential underlying biological mechanisms, the influence of covariates on these measures and briefly discuss the specificity and potential for remote monitoring by using these variables.

Classification of Mental Stress Levels by Analyzing fNIRS Signal Using Linear and Non-linear Features

Background: Mental stress is known as one of the main influential factors in development of different diseases including heart attack and stroke. Thus, quantification of stress level can be very important in preventing many diseases and in human health. Methods: The prefrontal cortex is involved in body regulation in response to stress. In this research, functional near infrared spectroscopy (fNIRS) signals were recorded from FP2 position in the international electroencephalographic 10–20 system during a stressful mental arithmetic task to be calculated within a limited period of time. After extracting the brain’s hemodynamic response from fNIRS signal, different linear and nonlinear features were extracted from the signal which are then used for stress levels classification both individually and in combination. Results: In this study, the maximum accuracy of 88.72% was achieved in classification between high and low stress levels, and 96.92% was obtained for the stress and rest states. Conclusion: Our results showed that using the proposed linear and nonlinear features it is possible to effectively classify stress levels from fNIRS signals recorded from only one site in the prefrontal cortex. Comparing to other methods, it is shown that the proposed algorithm outperforms other previously reported methods using the nonlinear features extracted from the fNIRS signal. These results clearly show the potential of fNIRS signal as a useful tool for early diagnosis and quantify stress.

The effect of resilience on task persistence and performance during repeated exposure to heat pain.

The Pain Resilience Scale was recently developed to assess dimensions of resilience critical to pain-related adaptation and was found to predict experimental pain sensitivity in a pain-free population. Pain resilience has also been theoretically linked to behavioral persistence despite pain. To date, however, this hypothesis has not been experimentally tested. To address this gap in the literature, in the current study 105 healthy young adults underwent a baseline administration of the Paced Auditory Serial Addition Test (PASAT), a stressful mental arithmetic task, delivered with somatosensory distraction (i.e. detection of warm and cool thresholds), and finally simultaneous administration of the PASAT and a series of five heat pain threshold assessments. Results of hierarchical multiple linear regressions indicated that, after controlling for scores on a baseline PASAT and pain sensitivity, pain resilience was positively related to task persistence, B=0.12, p=0.04, and task performance, B=0.14, p=0.04, on the PASAT. These findings provide novel support for the relationship between pain resilience and behavioral perseverance.

Cardiovascular reactions to psychological stress and abuse history: the role of occurrence, frequency, and type of abuse

ABSTRACTBackground and objectives: Extreme cardiovascular reactions to psychological stress have been associated with traumatic life experiences. Previous studies have focused on the occurrence or frequency of abuse rather than type of abuse. We examined how occurrence, frequency, and the type of abuse history are related to cardiovascular reactivity (CVR) to acute psychological stress. Design: The study consisted of between group and continuous analyses to examine the association between occurrence, type, and frequency of abuse with cardiovascular reactions to acute psychological stress. Methods: Data from 64 participants were collected. Heart rate, systolic blood pressure, and diastolic blood pressure were measured at baseline and during a standard mental arithmetic stress task. Results: Individuals who experienced abuse showed diminished CVR to acute psychological stress; this was driven specifically by the history of sexual abuse. Frequency of abuse did not relate to stress reactions. Conclusions: These findings accord with previous work suggesting a relationship between traumatic life experience and hypoarousal in physiological reactivity and extend previous findings by suggesting the relationship may be driven by sexual abuse.

Prolonged Reaction to Mental Arithmetic Stress in First-Degree Relatives of Schizophrenia Patients

Several studies have reported abnormal heart rate variability (HRV) in schizophrenia patients, suggesting a pathophysiological link between central autonomic dysfunction and symptoms of schizophrenia and that these could be heritable. This study aimed at evaluating cardiac autonomic response to mental arithmetic stress in first-degree relatives of schizophrenia patients (FDRS) employing HRV analysis. HRV measures were computed for 25 healthy FDRS and 25 age- and gender-matched controls during rest, mental arithmetic stress task and recovery period. Subtracting serial sevens from 700 for five minutes formed the stress task. Recovery period lasted five minutes starting from the termination of the stress task. Both groups showed similar alterations during the stress task. After stress termination, recovery to the basal values was observed in controls but not in patients' relatives, maintaining a pattern similar to that during the stress task. Poor recovery from cardiac autonomic functions (CAF) alterations induced by arithmetic stress may be a heritable trait marker of schizophrenia. Our report supports endophenotypic potential of HRV in schizophrenia research.

Underlying inflammation has no impact on the oxidative stress response to acute mental stress

Mental stress is considered to be a trigger for acute myocardial infarction (MI), with inflammation thought to provide a mechanism. Inflammation is reciprocally linked to oxidative stress, which has also been implicated in MI. The purpose of this study was to assess the effects of experimentally-induced inflammation on the oxidative stress response to mental stress in healthy participants. Healthy males undertook one of two inflammatory stimuli: typhoid vaccination (Vaccination paradigm, N=17) or eccentric exercise (Eccentric exercise paradigm, N=17). All participants completed a mental arithmetic stress task twice (within-subject design): 6h after the inflammatory stimulus, and during a control non-inflammation condition. Blood samples were taken before, immediately and 30min after the stress task. Plasma was assessed for interleukin-6 (IL-6), protein carbonyls (PC), lipid hydroperoxides (LOOH), total antioxidant capacity (TAC) and nitric oxide metabolites (NOx). Vaccination paradigm: IL-6, PC and NOx were significantly higher in the vaccination condition, relative to the control condition (p<.05). PC, TAC, LOOH and NOx were unchanged in response to mental stress in both the vaccination and control conditions. Eccentric Exercise paradigm: IL-6 and TAC were significantly higher in the eccentric exercise condition (p<.05), relative to the control condition. PC, TAC and NOx were unchanged in response to mental stress in both the eccentric exercise and control conditions. Two different inflammatory paradigms were successful in increasing selective plasma markers of inflammation and oxidative stress prior to a mental stress task. However, experimentally induced transient inflammation had no impact on mental stress-induced changes in plasma LOOH, PC, TAC or NOx in young healthy participants.

Disordered eating behaviour is associated with blunted cortisol and cardiovascular reactions to acute psychological stress

Research suggests a potential dysregulation of the stress response in individuals with bulimia nervosa. This study measured both cardiovascular and cortisol reactions to a standardised laboratory stress task in individuals identified as showing disordered eating behaviour to determine whether dysregulation of the stress response is characteristic of the two branches of the stress response system. Female students (N=455) were screened using two validated eating disorder questionnaires. Twelve women with disordered eating, including self-induced vomiting, and 12 healthy controls were selected for laboratory stress testing. Salivary cortisol and cardiovascular activity, via Doppler imaging and semi-automatic blood pressure monitoring, were measured at resting baseline and during and after exposure to a 10-min mental arithmetic stress task. Compared to controls the disordered eating group showed blunted cortisol, cardiac output, heart rate, and stroke volume reactions to the acute stress, as well as an attenuated vasodilatory reaction. These effects could not be accounted for in terms of group differences in stress task performance, subjective task impact/engagement, age, BMI, neuroticism, cardio-respiratory fitness, or co-morbid exercise dependence. Our findings suggest that disordered eating is characterised by a dysregulation of the autonomic stress-response system. As such, they add further weight to the general contention that blunted stress reactivity is characteristic of a number of maladaptive behaviours and states.

Blunted as well as exaggerated cardiovascular reactivity to stress is associated with negative health outcomes1

AbstractThe reactivity hypothesis implicates exaggerated cardiovascular reactions to acute psychological stress in the development of hypertension and other cardiovascular disease outcomes. However, exaggerated cardiovascular reactivity has also been suggested as a mediator between a variety of psychosocial and behavioral risk factors and cardiovascular disease. Recent data analyses from the West of Scotland Twenty‐07 study and our own group are discussed together, to show that blunted as well as exaggerated cardiovascular reactivity to stress may be associated with negative health outcomes. Blood pressure and heart rate were assessed at rest and during an acute mental arithmetic stress task. We show that depression and obesity are associated with blunted rather than exaggerated reactivity. These seemingly paradoxical results are discussed in terms of implications for the reactivity hypothesis.

High perceived stress in relation to life events is associated with blunted cardiac reactivity

The current study examined whether the perception of life stress related to cardiovascular reactivity. Participants (n=100) completed the Perceived Stress Scale, the Undergraduate Stress Questionnaire, and undertook a standard mental arithmetic stress task. Blood pressure and pulse rate were measured at baseline, during, and following stress task exposure. Reactivity was the difference between stress and baseline cardiovascular activity. A perceived stress difference score (PSDS) was calculated by subtracting the Undergraduate Stress Questionnaire scores from the Perceived Stress Scale scores. Two groups were created: high PSDS (n=15; PSDS at least 1SD above the mean) and low PSDS (n=15; PSDS at least 1SD below the mean). There was a significant difference between groups in pulse rate reactivity, F(1,28)=8.73, p=.006, η2=.24. High PSDS scores were associated with significantly lower pulse rate reactions to stress. Those who perceived their lives as more stressful than their actual stress exposures justified would appear to be characterised by blunted cardiac reactivity.

Sigh rate and respiratory variability during mental load and sustained attention

Spontaneous breathing consists of substantial correlated variability: Parameters characterizing a breath are correlated with parameters characterizing previous and future breaths. On the basis of dynamic system theory, negative emotion states are predicted to reduce correlated variability whereas sustained attention is expected to reduce total respiratory variability. Both are predicted to evoke sighing. To test this, respiratory variability and sighing were assessed during a baseline, stressful mental arithmetic task, nonstressful sustained attention task, and recovery in between tasks. For respiration rate (excluding sighs), reduced total variability was found during the attention task, whereas correlated variation was reduced during mental load. Sigh rate increased during mental load and during recovery from the attention task. It is concluded that mental load and task-related attention show specific patterns in respiratory variability and sigh rate.

Preliminary evidence that exercise dependence is associated with blunted cardiac and cortisol reactions to acute psychological stress

Low or blunted cardiovascular and cortisol reactions to acute psychological stress have been shown to characterise those with a tobacco or alcohol dependency. The present study tested the hypothesis that exercise dependency would be similarly associated with blunted reactivity. Young female exercisers (N = 219) were screened by questionnaire for exercise dependence. Ten women with probable exercise dependence and 10 non dependent controls were selected for laboratory stress testing. Cardiovascular activity and salivary cortisol were measured at rest and in response to a 10-min mental arithmetic stress task. The exercise dependent women showed blunted cardiac reactions to the stress task and blunted cortisol at 10, 20, and 30 minute post stress exposure. These effects could not be accounted for in terms of group differences in stress task performance, nor could the cardiac effects be attributed to group differences in cardio-respiratory fitness. It would seem that low stress reactivity is characteristic of a wide range of dependencies, and is not confined to substance dependence. Our results offer further support for the hypothesis that blunted stress reactivity may be a peripheral marker of a central motivational dysregulation.