Biomedical subjects

Frank H Wilhelm

Publications and source records attributed to Frank H Wilhelm.

At least 19 recordsLinked to original sources

PubMed2006

Reduced heart rate responding to trauma reliving in trauma survivors with PTSD: correlates and consequences.

The authors investigated whether heart rate (HR) responses to voluntary recall of trauma memories (a) are related to posttraumatic stress disorder (PTSD), and (b) predict recovery 6 months later. Sixty-two assault survivors completed a recall task modeled on imaginal reliving in the initial weeks postassault. Possible cognitive modulators of HR responsivity were assessed; dissociation, rumination, trauma memory disorganization. Individuals with PTSD showed a reduced HR response to reliving compared to those without PTSD, but reported greater distress. Notably, higher HR response but not self-reported distress during reliving predicted greater symptom reduction at follow-up in participants with PTSD. Engagement in rumination was the only cognitive factor that predicted lower HR response. The data are in contrast to studies using trauma reminders to trigger memories, which have found greater physiological reactivity in PTSD. The authors' observations are consistent with models of PTSD that highlight differences between cued or stimulus-driven retrieval and intentional trauma recall, and with E. B. Foa and M. J. Kozak's (1986) hypothesis that full activation of trauma memories facilitates emotional processing.

Adolescent↗

PubMed2006

Effects of lifestyle modification on the progression of coronary atherosclerosis, autonomic function, and angina--the role of GNB3 C825T polymorphism.

BACKGROUND: Given the multimodal medical and interventional treatment options in coronary artery disease, the additional value of intensified lifestyle modification is unclear. We have therefore examined the effects of lifestyle modification on top of current treatment and also associated with the GNB3 C825T polymorphism, which has established association to sympathetic activation and the precipitation of angina. METHODS: One hundred one patients with established coronary artery disease were randomized to a 1-year lifestyle modification group (lifestyle group [LG]) or an advice group. Risk factors, coronary calcification (electron beam tomography), heart rate variability, baroreflex sensitivity, anginal symptoms, and quality of life (QOL) were assessed on entry and after 1 year. RESULTS: Patients in LG had excellent program adherence, but lifestyle modification had no impact on metabolic risk factors and coronary calcification. Changes in heart rate, heart rate variability, and blood pressure were only slightly favoring LG. Baroreflex sensitivity increased by 2 (0.79-3.13) ms/mm Hg in the LG but decreased by -0.10 (-1.11 to 0.92) in the advice group (P = .013). Lifestyle modification led to improved physical QOL, reductions of anginal attacks (-54% vs 11%, P = .01), and dose reductions in 30% of anti-ischemic medications (P = .004). *825T allele carriers had a more pronounced reduction of heart rate and improvement of angina and QOL. The beneficial effect on reduction of medication was seen in *825T allele carriers only. CONCLUSIONS: In the presence of modern treatments, comprehensive lifestyle modification provides no additional benefits on progression of atherosclerosis but improves autonomic function, angina, and QOL with concomitant reduced need of medication. These responses are more pronounced in GNB3*825T allele carriers.

Aged↗

PubMed2006

Respiratory sinus arrhythmia, emotion, and emotion regulation during social interaction.

Respiratory sinus arrhythmia (RSA) figures prominently in emotional responding, but its exact role remains unclear. The present study tests two hypotheses: (1) Between-person differences in resting RSA are related to emotional reactivity, and (2) within-person changes in RSA are related to regulatory efforts. Pairs of women watched an upsetting film and discussed it. One woman in each of the experimental dyads was asked to either suppress or to reappraise during the conversation. Their partners and both members of the control dyads conversed naturally. Between-person differences in resting RSA were assessed with paced breathing, and within-person changes in RSA were calculated from baseline to the conversation accounting for respiration. Women with higher resting RSA experienced and expressed more negative emotion, and women who attempted to regulate their emotions either by suppressing or reappraising showed larger increases in RSA than controls.

Adolescent↗

PubMed2006

How to bite your tongue without blowing your top: implicit evaluation of emotion regulation predicts affective responding to anger provocation.

People frequently have to control their emotions to function in life. However, mounting evidence suggests that deliberate emotion regulation often is costly. This presents a dilemma: Is it better to let emotions go or to pay the price of exerting costly control? In two studies, the authors explore whether emotion regulatory processes associated with implicit positive evaluation of emotion regulation might provide the benefits of successful emotion regulation without the costs. In Study 1, the authors introduce a measure of implicit evaluation of emotion regulation (ER-IAT). Study 2 examined whether this measure is associated with actual emotional responses to an anger provocation. It was found that greater ER-IAT scores were associated with lesser anger experience, fewer negative thoughts, lessened self-reported effortful emotion regulation, and an adaptive pattern of cardiovascular responding. These findings suggest that implicit positive evaluation of emotion regulation is associated with successful, automatic, and physiologically adaptive down-regulation of anger.

Adaptation, Psychological↗

PubMed2006

Identifying anxiety states using broad sampling and advanced processing of peripheral physiological information.

Advances in biosignal acquisition and processing have provided an effective window to the complex peripheral physiology related to human emotions. Numerous cardiovascular measures have been used for assessing the activity of the sympathetic and parasympathetic branches of the autonomic nervous system. More recently, respiratory parameters have shown promise for the assessment of anxiety. Current theoretical accounts of anxiety recommend a broad assessment of anxiety responses involving measures from the physiological, behavioral and verbal-cognitive domain. However, practical and statistical considerations put restrictions on the number of dependent variables used in studies on emotion. In a laboratory experiment we assessed a large number of psychophysiological parameters to identify their relative utility for differentiating between a neutral (quiet sitting) and an anxious state induced by threat of shock. High effect sizes were found in all psychophysiological systems with electrodermal and behavioral responses demonstrating the highest, and respiratory and cardiovascular responses yielding medium and small effect sizes. A linear combination of the six most powerful variables was highly significant in distinguishing the neutral from the anxious state and resulted in 83.3% correct classification. Results demonstrate the necessity to include measures from multiple response domains for an adequate assessment of anxiety states. Furthermore, our results point to the significance of respiratory parameters in anxiety assessment.

Adult↗

PubMed2006

Reliability of respiratory tidal volume estimation by means of ambulatory inductive plethysmography.

Ambulatory monitoring of ventilatory parameters in everyday life, field research and clinical situations may offer new insights into respiratory functioning in health and disease. Recent technological advances that employ ambulatory inductive plethysmography could make monitoring of respiration outside the clinic and laboratory feasible. Inductive plethysmography provides a method for nonintrusive assessment of both timing (e.g. respiration rate) and volumetric parameters (e.g. tidal volume and minute ventilation), by which tidal volume is initially calibrated to direct measures of volume. Estimates of tidal volume assessed by this technique have been validated in laboratory investigations, usually examining within-individual relations to direct measures over a large range of tidal volume variation. However, the reliability of individual differences in tidal volume or other breathing parameters has not been tested under naturalistic measurement conditions using inductive plethysmography. We examined the test-retest reliability of respiration rate, tidal volume and other volumetric parameters of breathing over a period of six weeks of repeated measurements during baseline conditions and breathing exercises with 16 healthy freely moving volunteers in a Yoga course. Reliability of measurement was evaluated by calculating the average week-to-week between-subject correlation coefficients for each physiological measure. Additionally because body-mass index has been previously positively correlated to tidal volume, we also assessed this relationship as an external criterion of validity of tidal volume estimation. Regarding the latter, similar correlations to those previous studies were found (r = 0.6). Furthermore, reliability estimates were high and consistent across respiratory measures (typically r's = 0.7-0.8). These results suggest the validity of ambulatory inductive plethysmographic measurement of respiration, at least under relatively sedentary conditions. Findings also point to the stability of individual differences in respiratory parameters over consecutive weeks.

Activities of Daily Living↗

PubMed2006

Distinguishing emotional from physical activation in ambulatory psychophysiological monitoring.

Ambulatory monitoring has gained powerful new tools due to recent electronic and computer advances. The capability simultaneously to monitor numerous physiological parameters and behavior enhances the ecological validity of field assessment, but methodological challenges abound that can compromise attempts to understand biobehavioral relations in the real world. A major obstacle is that physiological dysregulation or emotion effects can be masked by variation in physical activity. Using a multi-channel ambulatory recording system, a wide array of self-report, physiological and environmental measurements was collected from 28 participants during quiet sitting, physical exercise and an emotion induction consisting of a short commercial flight. Half of the participants were selected to respond to flying with intense anxiety, the other half, with moderate excitement. Recorded channels included ECG, EDA, calibrated respiration pattern, and skin temperature, from which 17 physiological parameters were calculated. Accelerometry and self-report in an emotion diary served as manipulation checks. Results indicate that many parameters, including heart rate, respiratory sinus arrhythmia, and skin conductance level and its fluctuation rate, were strongly and nonspecifically affected by both anxiety and exercise. However, parameters of respiratory volume were particularly responsive to exercise, while certain parameters of irregularity in breathing were to anxiety. Several respiratory timing parameters were responsive to both exercise and excitement. We conclude that physiological measures provide information helping to distinguish emotional from physical activation. However, additional context awareness is necessary for confident data interpretation in ambulatory recording. This can be achieved by specific channels such as accelerometry, items in an electronic diary, semi-structured protocols, and statistical modeling.

Diagnosis, Computer-Assisted↗

PubMed2005

Cell aging in relation to stress arousal and cardiovascular disease risk factors.

We previously reported that psychological stress is linked to and possibly accelerates cellular aging, as reflected by lower PBMC telomerase and shortened telomeres. Psychological stress is a major risk factor for cardiovascular disease (CVD), with multiple behavioral and physiological mediators. Telomere shortness has been associated with CVD, but the relationship between low telomerase activity, a potential precursor to telomere shortening, and CVD risk factors has not been examined in humans. Here we examine whether telomere length and telomerase in leukocytes are associated with physiological signs of stress arousal and CVD risk factors in 62 healthy women. Low telomerase activity in leukocytes was associated with exaggerated autonomic reactivity to acute mental stress and elevated nocturnal epinephrine. Further, low telomerase activity was associated with the major risk factors for CVD -smoking, poor lipid profile, high systolic blood pressure, high fasting glucose, greater abdominal adiposity-as well as to a composite Metabolic Syndrome variable. Telomere length was related only to elevated stress hormones (catecholamines and cortisol). Thus, we propose that low leukocyte telomerase constitutes an early marker of CVD risk, possibly preceding shortened telomeres, that results in part from chronic stress arousal. Possible cellular mechanisms by which low telomerase may link stress and traditional risk factors to CVD are discussed. These findings may implicate telomerase as a novel and important mediator of the effects of psychological stress on physical health and disease.

Adaptation, Psychological↗

PubMed2005

Mechanisms of virtual reality exposure therapy: the role of the behavioral activation and behavioral inhibition systems.

J. A. Gray's (1975) theory distinguishes between two motivational systems, which he refers to as the behavioral activation system (BAS) and the behavioral inhibition system (BIS). D. C. Fowles (1980) has shown that heart rate responses reflect activity of the BAS, and electrodermal responses reflect activity of the BIS. Both BAS and BIS are reliably activated during in-vivo exposure to fearful situations (F. H. Wilhelm & W. T. Roth, 1998). However, due to the constraints imposed by virtual reality (VR), we hypothesized that VR exposure to fearful situations would activate the BIS alone. To test this hypothesis, a VR free-standing elevator simulation was presented to participants selected for high and low fear of heights. As predicted, the high-anxious group strongly responded electrodermally (effect size d = 1.53), but showed only minimal HR elevations during exposure (d = 0.12), and little other cardiovascular or respiratory changes. The low-anxious control group showed little electrodermal and HR reactivity (d = 0.28 and 0.12). A comparison with data from a previous study demonstrated that this pattern was in stark contrast to the large electrodermal and cardiovascular response observed during situational in-vivo exposure outside the laboratory. We conclude that the BIS, but not BAS, is selectively activated during VR exposure, causing discordance between self-report and commonly used physiological measures of anxiety. Results are discussed within the framework of E. B. Foa & M. J. Kozak's (1986) emotional processing theory of fear modification, suggesting different mechanisms underlying VR and in-vivo exposure treatments.

Adolescent↗

PubMed2005

Voluntary hyperventilation in the treatment of panic disorder--functions of hyperventilation, their implications for breathing training, and recommendations for standardization.

Hyperventilation has numerous theoretical and empirical links to anxiety and panic. Voluntary hyperventilation (VH) tests have been applied experimentally to understand psychological and physiological mechanisms that produce and maintain anxiety, and therapeutically in the treatment of anxiety disorders. From the theoretical perspective of hyperventilation theories of anxiety, VH is useful diagnostically to the clinician and educationally to the patient. From the theoretical perspective of cognitive-behavior therapy, VH is a way to expose patients with panic disorder to sensations associated with panic and to activate catastrophic cognitions that need restructuring. Here we review panic disorder treatment studies using breathing training that have included VH. We differentiate the roles of VH in diagnosis, education about symptoms, training of breathing strategies, interoceptive exposure, and outcome measurement--discussing methodological issues specific to these roles and VH test reliability and validity. We propose how VH procedures might be standardized in future studies.

Anxiety Disorders↗

PubMed2005

Psychophysiological assessment during exposure in driving phobic patients.

A comprehensive assessment of fear or anxiety requires measurement of both self-report and physiological responses. Respiratory abnormalities have been rarely examined during real-life exposure, although they are an integral part of fear. Twenty-one women with a specific driving phobia and 17 nonphobic women were psychophysiologically monitored during 2 highway-driving sessions; phobic women completed an additional session. Respiratory movements, end-tidal partial pressure of carbon dioxide, an electrocardiogram, skin conductance, and skin temperature were recorded. Phobic patients differed from control participants both physiologically and experientially before, during, and after exposure. Effect size during exposure was large for the authors' measure of hyperventilation. Discriminant analysis indicated that multiple physiological measures contributed nonredundant information and correctly classified 95% of phobic and control participants. Thus, selected respiratory and autonomic measures are valid diagnostic and therapeutic outcome criteria for this situational phobia.

Adult↗

PubMed2005

Are current theories of panic falsifiable?

The authors examine 6 theories of panic attacks as to whether empirical approaches are capable of falsifying them and their heuristic value. The authors conclude that the catastrophic cognitions theory is least falsifiable because of the elusive nature of thoughts but that it has greatly stimulated research and therapy. The vicious circle theory is falsifiable only if the frightening internal sensations are specified. The 3-alarms theory postulates an indeterminate classification of attacks. Hyperventilation theory has been falsified. The suffocation false alarm theory lacks biological parameters that unambiguously index dyspnea or its distinction between anticipatory and panic anxiety. Some correspondences postulated between clinical phenomena and brain areas by the neuroanatomical hypothesis may be falsifiable if panic does not depend on specific thoughts. All these theories have heuristic value, and their unfalsifiable aspects are capable of modification.

Cognition↗

PubMed2005

The tie that binds? Coherence among emotion experience, behavior, and physiology.

Emotion theories commonly postulate that emotions impose coherence across multiple response systems. However, empirical support for this coherence postulate is surprisingly limited. In the present study, the authors (a) examined the within-individual associations among experiential, facial behavioral, and peripheral physiological responses during emotional responding and (b) assessed whether emotion intensity moderates these associations. Experiential, behavioral, and physiological responses were measured second-by-second during a film that induced amusement and sadness. Results indicate that experience and behavior were highly associated but that physiological responses were only modestly associated with experience and behavior. Intensity of amusement experience was associated with greater coherence between behavior and physiological responding; intensity of sadness experience was not. These findings provide new evidence about response system coherence in emotions.

Adolescent↗

PubMed2005

Adaptive and wavelet filtering methods for improving accuracy of respiratory measurement.

Respiratory activity is commonly measured by chest and abdomen bands using respiratory inductive plethysmography (RIP) or similar techniques. Such respiratory signals pose special challenges to adequate processing since the range of natural breathing frequencies is wide, and movement artifacts are common during periods of physical activity and even during sleep. Presented are novel linear and nonlinear signal processing algorithms that enable the decomposition of the range of artifact generated by non-respiratory sensor movement, enabling the respiratory component to be retrieved. We evaluated the performance of these techniques for improved processing of human respiratory signals. We demonstrate that, in contrast to conventional low-pass filters that attenuated higher frequency breathing and swift respiratory events such as cough episodes, a soft thresholding technique applied to a set of wavelet filterbanks effectively denoised the signal without attenuating respiratory information. Another type of artifact, low frequency noise generated from walking or running motion, can appear as breathing at the pace frequency making it difficult to differentiate a breath from a heel strike. Since this artifact often resides in the respiratory frequency band it cannot be removed by classical or wavelet filtering methods. We introduce an adaptive filtering technique that uses an upward body acceleration signal as a reference to resolve the respiratory component. A real-life data set acquired with a novel ambulatory and sleep monitoring system (LifeShirt, VivoMetrics, Inc., Ventura, CA, USA) demonstrates the utility of these respiratory filtering approaches and indicates that accurate respiratory volume and timing information can be collected noninvasively in physically active subjects in- and outside the laboratory or clinic.

Algorithms↗

PubMed2005

Classification of locomotor activity by acceleration measurement: validation in Parkinson disease.

The number of steps per time period is an important ambulatory measure describing an individual's locomotor function with implications for psychological and physical health. Key applications in neurology, psychiatry, psychopharmacology, and sports, behavior or rehabilitation medicine make it desirable to improve step detecting devices. Several pedometer or wrist actigraphy monitors exist today, but are insensitive or confounded by movement style, which may vary for different diagnoses and applications. Presented is an algorithm that detects, classifies and counts steps related to walking, running and shuffling motion. Data is recorded using a novel ambulatory monitoring system (LifeShirt, VivoMetrics, Inc., Ventura, CA, USA) which captures breathing information from respiratory inductive plethysmography (RIP) sensors embedded in a light garment, and acceleration signals from a dual axis accelerometer attached close to the center of body mass. The vertical accelerometer axis measures upward acceleration generated by walking and running, while the other axis measures movement common with shuffling gait. Since these signals often contain noise and artifact due to soft tissue movement or external vibrations they are filtered and autocorrelated using unbiased estimates. The autocorrelation coefficients allow for clearer detection and classification of the cyclic motion during walking, running and shuffling movements. The algorithm is tested during various levels of exercise in healthy individuals and patients suffering from Parkinson disease, which is often characterized by shuffling gait. The results demonstrate an effective locomotor-monitoring algorithm that can produce accurate estimates of frequency and intensity of steps and shuffles and help classify daily locomotor activities.

Acceleration↗

PubMed2005

Assessment of heart rate variability during alterations in stress: complex demodulation vs. spectral analysis.

Complex demodulation (CDM) has been proposed as a method for the analysis of high- and low-frequency variabilities of heart rate and blood pressure under non-stationary conditions. In contrast to power spectral analysis, CDM provides time-dependent changes in signal amplitude and frequency on a continuous basis and may yield insights into short-term alterations in autonomic regulation. In particular, CDM may be uniquely suited for quantifying changes in respiratory sinus arrhythmia (RSA) at the onset of acute physical or mental stress conditions. In a simulation analysis we generated R-R interval time series within a normal physiological range that represented different typical sources of non-stationarity present during varying stress. Sources of non-stationarity included abrupt changes in a) mean level (from 1000 to 500 ms within 60 sec), b) oscillatory amplitude (from 50 to 10 ms), c) oscillatory frequency (from 0.2 to 0.4 Hz), and d) a combination of the above. In general, CDM-estimated amplitude and frequency accurately reproduced characteristics of the simulation data under all conditions, even after substantial noise and a 0.09 Hz oscillation were added. However, during some transitions CDM estimates fluctuated around the true values for up to 15 sec before they stabilized. Compared to CDM, power spectral analysis results were less informative since they did not allow the disentangling of unique contributions of distinct amplitudes and frequencies at different time points. Our analyses indicate that CDM provides a powerful means of continuously assessing time-dependent changes in RSA during varying physical or mental stress. CDM may also hold promise for a range of physiological and environmental non-steady state conditions where rapid dynamic alterations in autonomic control are likely to occur.

Algorithms↗

PubMed2004

Respiratory feedback for treating panic disorder.

Panic disorder patients often complain of shortness of breath or other respiratory complaints, which has been used as evidence for both hyperventilation and false suffocation alarm theories of panic. Training patients to change their breathing patterns is a common intervention, but breathing rarely has been measured objectively in assessing the patient or monitoring therapy results. We report a new breathing training method that makes use of respiratory biofeedback to teach individuals to modify four respiratory characteristics: increased ventilation (Respiratory Rate x Tidal Volume), breath-to-breath irregularity in rate and depth, and chest breathing. As illustrated by a composite case, feedback of respiratory rate and end-tidal pCO2 can facilitate voluntary control of respiration and reduce symptoms. Respiratory monitoring may provide relevant diagnostic, prognostic, and outcome information.

Biofeedback, Psychology↗

PubMed2004

Increased high-frequency heart rate variability during insulin-induced hypoglycaemia in healthy humans.

Despite causing sympathetic activation, prolonged hypoglycaemia produces little change in HR (heart rate) in healthy young adults. One explanation could be concurrent parasympathetic activation, resulting in unchanged net effects of autonomic influences. In the present study, hypoglycaemic (2.7 mmol/l) and normoglycaemic (4.7 mmol/l) hyperinsulinaemic clamp studies were performed after normoglycaemic baseline clamp periods with 15 healthy volunteers (seven male; mean age, 27 years) on two occasions in a randomized single-blind cross-over design. Non-invasive indices of cardiac autonomic activity and hormones were measured at baseline and 1 h after the beginning of hypoglycaemia or control normoglycaemia. Plasma insulin levels and mean HR were similar during both conditions. During hypoglycaemia, there was a 485% increase in plasma adrenaline (epinephrine). A shortening of the pre-ejection period by 45% suggested strong sympathetic cardiac activation. High-frequency (0.15-0.45 Hz) HRV (HR variability) increased, indicating a concomitant increase in parasympathetic tone. Thus, during hypoglycaemia-induced sympathetic cardiac activation in healthy adults, parasympathetic mechanisms are involved in stabilizing mean HR.

Adult↗