Biomedical subjects

Omer Van den Bergh

Publications and source records attributed to Omer Van den Bergh.

At least 19 recordsLinked to original sources

PubMed2006

Differentiation between the sensory and affective aspects of histamine-induced bronchoconstriction in asthma.

Respiratory symptom perception research has focused mainly on respiratory sensations. Because dyspnea is multidimensional, affective aspects should be investigated. Patients with asthma (N=25) underwent a histamine provocation until a 20% fall in forced expiratory volume in 1s (FEV(1)). After each dose level, 6 symptoms of dyspnea intensity and 6 symptoms of dyspnea affectivity were rated. Individual perceptual sensitivity was determined by calculating the linear slope between the fall in FEV(1) and the increase in the total symptom score, and for affective and sensory symptoms separately [Bijl-Hofland, Folgering, van den Hoogen, et al. Perception of bronchoconstriction in asthma patients measured during histamine challenge test. Eur Respir J 1999;14:1049-54]. Trait anxiety, baseline state anxiety, daily asthma symptoms and catastrophizing during an asthma exacerbation were also assessed. Sensitivity was unrelated to physiological indices of disease severity (i.e., baseline FEV(1) and histamine dose level at 20% fall in FEV(1)), whereas it was positively related to trait anxiety, state anxiety, daily asthma symptoms and catastrophic thinking during an asthma exacerbation in daily life. These relationships were overall much stronger for affective than for sensory symptom slopes. In stepwise multiple regressions, state anxiety was the best predictor of the affective symptom slopes, whereas catastrophic thinking during an asthma exacerbation was the best predictor for the sensory symptom slopes. The differentiation between sensory and affective components of dyspnea adds to the understanding of respiratory symptom perception in asthma.

Adolescent↗

PubMed2006

The repeated confrontation with videotapes of spiders in multiple contexts attenuates renewal of fear in spider-anxious students.

In a treatment-analogue experiment, extinction of fear of spiders was investigated in a group of spider-anxious students. Two groups were created: in the single extinction group the extinction trials consisted of repeated presentations of a videotaped spider in one specific location of a house, whereas in the multiple extinction group the trials consisted of videotapes of the same spider in three different locations of a house. Also a control group was included that was exposed to videotapes of the location but without the spider. As reflected in skin conductance responses and self-report data, fear of spiders was significantly reduced in the two extinction groups compared to the control group. Moreover, when the extinction groups were confronted with the videotape of the spider in a new location, the single extinction group did not show generalisation of extinction, whereas the multiple extinction group did. These results corroborate the existing evidence for context dependence of extinction of fear and provide new evidence that the use of multiple contexts during extinction might improve the generalisability of extinction in humans. Implications for exposure therapy are discussed.

Adolescent↗

PubMed2006

Anxiety and respiratory variability.

Associations of inter- and intra-individual differences in anxiety and fear with within subject variability in breathing parameters were explored. Timing and volume components of respiration and FETCO(2) were measured non-intrusively before and during anxious and fearful imagery in 98 young women. Trait anxiety was associated with less variability in several breathing parameters during baseline preceding imagery. Significant decreases in the variability of expiratory time and inspiratory drive were also observed during anxious imagery. During fearful imagery, however, the variability of FETCO(2) increased compared to baseline. Results on anxiety are largely in agreement with models that posit that healthy systems are characterized by variability and flexibility. The paradoxical findings for fearful imagery enhance the importance of a distinction between fearful and anxious affects.

Adaptation, Physiological↗

PubMed2006

Association of substance-use behaviours and their social-cognitive determinants in secondary school students.

In two samples of Flemish secondary school students, co-occurrence of different types of substance use was observed: smoking was associated with marijuana use in Sample 1 (n = 597) and alcohol consumption in Sample 2 (n = 403). It was investigated whether social-cognitive determinants of these behaviours were also associated. Low to medium correlations were observed. Confirmatory factor analyses showed that a model with general social-cognitive factors (across different substances) did not have adequate fit. Substance use was mainly associated with variables referring to the specific substance under consideration, with the exception of self-efficacy in buying and smoking cigarettes; this factor was linked not only to smoking but also to alcohol and marijuana use. Adolescents who regularly used two substances generally held positions on social-cognitive scales that were more unfavourable than those who only used one substance. In order to change determinants of use, substance-specific cognitions and skills may be important targets.

Adolescent↗

PubMed2006

US-inflation in a differential odor-conditioning paradigm is not robust: relevance for medically unexplained symptoms.

Reported somatic symptoms without clear relation to physiological processes are studied. A learning paradigm was used with two odors (CSs) and the inhalation of CO(2)-enriched air (US), while measuring symptom levels and respiratory behavior. After paring one odor with the CO(2)-enriched air and the other odor with air, half of the participants received a US-inflation manipulation (information manipulation and enhanced US). Subsequently, all participants received both odors with air (test). A difference between the odor previously paired with CO(2)-enriched air and the odor previously paired with air was found for the symptom measure, US-expectancy ratings, and, to a lesser extent, for respiratory volume. No differences, however, were found between the group receiving the US-inflation manipulation and a group not receiving this manipulation. The results indicate that, despite a successful learning of reported symptoms, US-inflation does not seem to be robust.

Acetic Acid↗

PubMed2006

Air hunger and ventilation in response to hypercapnia: effects of repetition and anxiety.

We investigated the effects of anxiety on the intensity of air hunger during gradually increasing levels of CO2 until the end-tidal fractional concentration of CO2 was 7.9% or air hunger was intolerable. Normal high and low (trait) anxious participants (N=23) went through three rebreathing trials (15 min interval). Breathing behaviour was continuously monitored and air hunger was rated every 12 s. The threshold for responding to the increased CO2 was always lower for the subjective rating than for the ventilatory response. Habituation across trials was observed for both the ventilatory response and the air hunger rating regardless of anxiety. However, beyond the threshold, the slope in air hunger ratings decreased across trials in low anxious persons and tended to increase in high anxious persons (interaction P<0.05). No differences occurred in the slopes of the breathing responses. The findings documented uncoupling of the physiological and subjective responses during CO2-induced air hunger.

Adolescent↗

PubMed2005

Effects of long-acting bronchodilators and placebo on histamine-induced asthma symptoms and mild bronchusobstruction.

STUDY OBJECTIVE: Accurate perception of airway caliber remains an important issue in asthma management. The way bronchodilation is perceived is partly related to the perception of the efficacy of bronchodilators in relieving complaints. In the present study, we compared the effects of salmeterol, formoterol and placebo on relief of histamine-induced asthma symptoms and mild bronchusobstruction. METHODS: In this randomized controlled, double blind study, 30 asthmatics were challenged with histamine until forced expiratory volume in 1s (FEV(1)) fell with > or =20%. Subjects received salmeterol, formoterol or placebo after the histamine provocation. Pulmonary function (FEV(1)) and asthma symptoms (Asthma Symptom Checklist, Borg Dyspnea Scale) were assessed 5 and 20 min later. RESULTS: FEV(1) improved significantly more in the salmeterol and formoterol group than in the placebo group (P<0.001, P<0.001 and P<0.05, respectively). Salmeterol and formoterol were not different with regard to the pulmonary function recovery. No significant differences were found between the effects of salmeterol, formoterol and placebo on any of the symptom responses at the different time points. CONCLUSIONS: We conclude that after a histamine-induced mild bronchusobstruction, a similar asthma symptom recovery occurred when inhaling salmeterol, formoterol or placebo, despite better recovery of pulmonary function in the active drug conditions.

Adult↗

PubMed2005

Negative affectivity and enhanced symptom reports: differentiating between symptoms in men and women.

This study aimed to characterize individual bodily symptoms as regards their differential relationship with negative affectivity (NA). In a first step, 73 symptoms were rated by independent groups of raters (psychologists, medical doctors, healthy students) on the following characteristics: the extent to which a symptom (1) refers to a specific location in the body (vagueness), (2) may refer to both a physical condition and a negative emotional state (overlap), and (3) is likely to be a physiological manifestation of anxiety (anxiety). Each symptom was also rated on (4) the probability that it is caused by a clearly defined somatic pathology (somatic pathology), (5) how life-threatening or (6) compromising for the quality of life a symptom is, and (7) how worried one would be if the symptom were to be experienced in daily life (worrying). Two factors, severity and somatic versus psychic, explained 75% of the variance in the ratings on the symptom characteristics. Next, based on the data of 1017 university students (858 women), correlations of each individual symptom with NA were calculated for each gender. The pattern of correlation was highly variable and differed in important ways for men and women. Whereas the correlation of an individual symptom with NA could be predicted by both symptom factors in women (R(2)=52%), only the somatic versus psychic factor was a significant predictor in men (R(2)=11%). These results suggest that (1) NA should not be considered a general complaining factor, and (2) important gender differences exist regarding the type of symptoms that relate most strongly to NA.

Adolescent↗

PubMed2005

Olfactory classical conditioning in newborn mice.

Determining the behavioural phenotype of genetically altered mice is a valuable approach for elucidating the function of genes and their role in cognitive disorders. Methods for phenotyping newborn mice are scarce and generally confined to sensorimotor reflexes. Here, we describe a simple method for assessing associative abilities in newborn mice. We used a two-odour-choice classical conditioning paradigm in mice from the day of birth (post-natal age 0, P0) to P6. Acquisition required 20 trials: 10 trials during which the pups were placed over the conditioned stimulus (CS+) odour (lemon or peppermint) for 30s and simultaneously stroked gently with a paintbrush and 10 trials during which the pups were placed over the other odour (CS-) for 30s, without stroking. Then, the pups were subjected to five odour-preference trials to test for conditioning. This sequence of five trials was repeated after 5 and 24h to assess retention of the conditioned odour preference. During the immediate post-acquisition sequence, the pups spent significantly more time over the CS+ than over the CS- (p<0.0001). No extinction of the conditioned preference was observed during this test. No preference was observed after 5 or 24h, indicating that the conditioned response was promptly lost. Conditioning was effective as soon as P0-P1. Thus, conditioning may emerge in newborn mice sooner than previously reported. This paradigm is well suited to phenotyping of large samples of genetically altered mice and may shed light on the role for genes in paediatric cognitive impairments.

Age Factors↗

PubMed2005

Reinstatement of fear responses in human aversive conditioning.

The treatment of choice for a number of anxiety disorders is exposure therapy. However, successful reduction of fear through exposure is sometimes followed by a (partial) return of symptoms of fear (return of fear, ROF; Clin. Psychol. Rev. 9 (1989) 147). Several possible learning mechanisms have been suggested to explain ROF (e.g. mechanisms related to spontaneous recovery, renewal, reacquisition and reinstatement). The present study focuses on reinstatement, which refers to the observation that mere US-only presentations can 'reinstate' previously extinguished fear responses. Although animal research has repeatedly demonstrated this phenomenon, little is known about fear reinstatement in humans. The present study employed a differential aversive conditioning procedure: after acquisition and a subsequent extinction procedure, a series of four unpredicted US-only trials was scheduled in the reinstatement group. The control group did not receive additional US presentations. A significant reinstatement effect was observed for US-expectancy ratings and fear ratings in the reinstatement group, but not in the control group. No differences were observed in a reaction time measure of resource allocation to the conditioned stimuli. These findings constitute a first demonstration of reinstatement of conditioned fear responses in humans. Implications for exposure treatment and suggestions for future research are discussed.

Adult↗

PubMed2005

Accuracy of respiratory symptom perception in different affective contexts.

OBJECTIVE: The accuracy of respiratory symptom perception was investigated in different affective contexts in participants (N=48) scoring high or low for negative affectivity (NA). METHODS: Within-subject correlations were calculated between two subjective ratings and their respective physiological referent (the rating of "deeper breathing" and respiratory volume, and rating of "faster breathing" and breathing frequency) across nine consecutive breathing trials. Three different air mixtures were used: room air, air enriched with 7.5% CO(2), and with 10% CO(2). For half the participants, the trials were framed in a pleasant context, created by adding a pleasant odour to the air mixture in addition to information announcing pleasant feelings as a result of breathing the air mixtures. The other half received the trials in a distressing context: A foul smelling odour was added and the information announced unpleasant feelings. RESULTS: High-NA persons were overall less accurate than were low-NA persons in the perception of respiratory volume. For breathing frequency, high-NA persons were significantly less accurate in the distressing condition than in the pleasant one, whereas for low-NA persons, the information frame did not matter. CONCLUSION: The study shows that the accuracy of respiratory symptom reports is reduced in high-NA persons, especially in a distressing context.

Adolescent↗

PubMed2005

Respiratory complaints in Chinese: cultural and diagnostic specificities.

STUDY OBJECTIVES: We investigated the qualitative components of a wide range of Chinese descriptors of dyspnea and associated symptoms, and their relevance for clinical diagnosis. MEASUREMENTS: Sixty-one spontaneously reported descriptors were elicited in Chinese patients to make a symptom checklist, which was administered to new groups of patients with different cardiopulmonary diseases, to patients with medically unexplained dyspnea and to healthy subjects. RESULTS: Test-retest reliability was satisfactory for most of the descriptors. A principal component analysis on 61 descriptors yielded the following eight factors: dyspnea-effort of breathing; dyspnea-affective aspect; wheezing; anxiety; tingling; palpitation; coughing and sputum; and dying experience. Although the descriptors of dyspnea-effort of breathing resembled Western wordings and were shared by patients with a variety of diseases, the descriptors of dyspnea-affective aspect appeared to be more culturally specific and were primarily linked to the diagnosis of medically unexplained dyspnea, whereas wheezing was specifically linked to asthma. CONCLUSIONS: Three factors of breathlessness were found in Chinese. The descriptors of dyspnea-effort of breathing and wheezing appear to be similar to Western descriptors, whereas the dyspnea-affective aspect seems to bear cultural specificity.

Adolescent↗

PubMed2005

Understanding participation in an asthma self-management program.

STUDY OBJECTIVE: Asthma education programs improve asthma treatment results significantly. Low participation rate is a recurrent problem that impedes the efficiency of those programs. The purpose of this study was to investigate social cognitive determinants of the intention to participate in an asthma self-management program. DESIGN: Structured interview. SETTING: Outpatient clinic, University Hospital Gasthuisberg, Leuven, Belgium. PATIENTS: One hundred seven asthmatic outpatients (mean age 42 years; 35% male). INTERVENTIONS: Patients received a standard explanation about the asthma program, were invited to participate, and were questioned about their beliefs about the program offered. MEASUREMENTS AND RESULTS: A social cognitive framework (attitude, social influence, and self-efficacy model) was used to compose a structured interview that was administered to assess the patients' attitude toward the program (perceived benefits), their social influence, and self-efficacy expectations to participate (perceived barriers). Asthma-related health behavior and clinical and demographic characteristics were evaluated by means of questionnaires. Fifty-nine percent of the patients expressed the intention to participate. Logistic regression analysis resulted in a model explaining 72% of the variance of intentions (Nagelkerke R(2) = 0.72). Having few structural barriers to participate was a significant predictor of participation (odds ratio [OR], 12.5; 95% confidence interval, 5.2 to 19.3), next to believing in the personal benefits of the program (OR, 7.6; 95% confidence interval, 2.4 to 12.5), social influence (OR, 3.3; 95% confidence interval, 1.3 to 8.4), and education level (OR, 2.7; 95% confidence interval, 1.3 to 5.6). CONCLUSIONS: Recruitment of patients with asthma for an educational program should emphasize personal benefits of the program, should include patients' social network, and should consider the impact of structural barriers on participation behavior.

Adult↗

PubMed2004

Perceived relation between odors and a negative event determines learning of symptoms in response to chemicals.

BACKGROUND: We investigated the effects of worrying information about chemical pollution on subjective symptoms in response to an odor that was previously associated with symptom episodes. METHODS: Ammonia and butyric acid in harmless concentrations were used as odor cues, and 10% CO2-enriched air was used to induce symptoms. One of two odors was consistently mixed with CO2-enriched air while the other odor was presented in room air during 80 s breathing trials (three trials of each). Next, information framing the experiment in the context of possible health-damaging effects of chemical pollution of our environment was presented to half the participants, whereas no information was given to the other half. Finally, both odor cues were presented with room air. Symptom scores were used as the dependent variable. RESULTS: Unexpectedly, participants reported more symptoms in response to the odor previously presented with air than to the odor previously presented with CO2-enriched air. Post-hoc analyses suggested a crucial role for perceived rather than actual contingencies between odor and symptom episodes. Information manipulation had no effect. CONCLUSIONS: Believing that a specific odor cue was associated with a symptom episode was more important than the actual association in order to provoke symptoms in response to harmless odor cues.

Adolescent↗

PubMed2004

Contingency awareness in a symptom learning paradigm: necessary but not sufficient?

In previous studies, we found that bodily symptoms can be learned in a differential conditioning paradigm, using odors as conditioned stimuli (CSs) and CO2-enriched air as unconditioned stimulus (US). However, this only occurred when the odor CS had a negative valence (a selective conditioning effect), and tended to be more pronounced in persons scoring high for Negative Affectivity (NA). This paper considers the necessity and/or sufficiency of awareness of the CS-US contingency in three studies using this paradigm. The relation between contingency awareness and the selective conditioning effect, and between contingency awareness and NA was also considered. Both self reported symptoms and respiratory physiology served as dependent variables. A learning effect on symptoms was found only for participants aware of the CS-US contingency, but not all participants reporting contingency awareness showed a learning effect. No conditioning effects appeared on the physiological measures. Also contingency awareness did not account for the selective conditioning effect, and did not interact with NA. Overall, the necessity but insufficiency hypotheses can only be withhold for group data and not for individual data.

Adolescent↗

PubMed2004

Dyspnea: the role of psychological processes.

Breathlessness or dyspnea-the subjective experience of breathing discomfort-is a symptom in many pulmonary, cardiovascular, and neuromuscular diseases. It occurs in normals as well during intense emotional states and heavy labor or exercise. In clinical cases, it generally causes severe suffering. Dyspnea has multifactorial causes and the explanation for the symptom may differ largely among patients. Explanatory models imply the involvement of mechanisms at several levels of functioning, such as afferent signals from the respiratory muscles or blood gas levels related to hypercapnia and hypoxia. Depending on the relative involvement of specific mechanisms and their interactions, dyspnea may be experienced differently and subtypes can be distinguished. More recently, perceptual-cognitive and emotional processes related to symptom perception and interpretation have been investigated in the context of dyspnea. In this review, we focus on the psychological processes that play part in the perception of dyspnea and formulate some practical guidelines for those who are confronted with dyspnea.

Arousal↗

PubMed2004

Negative affectivity and the influence of suggestion on asthma symptoms.

OBJECTIVE: To investigate the effect of suggestion on subjective and objective asthma symptoms as a function of negative affectivity of the patients. METHODS: Asthmatics (n=32) took puffs from three separate placebo inhalers, being described as an inert (practice) substance, a bronchoconstrictor, and a bronchodilator. Negative affectivity, social desirability, probability of medication-intake, intensity of asthma symptoms and total respiratory resistance were measured at onset. The latter three measures were repeated after each trial. Heart rate, end tidal PCO(2), and breathing behaviour were measured during each trial. RESULTS: Asthmatics with high negative affectivity had overall more intense asthma symptoms. They also reported more airway obstruction after suggested bronchoconstriction and less after suggested bronchodilation, whereas persons with low negative affectivity did not show such variation. These effects were unrelated to social desirability. Respiratory symptoms correlated with the odds of medication intake. Neither negative affectivity nor suggestion influenced lung function and only breathing parameters under voluntary control changed as a function of suggestion. CONCLUSION: Self-reported symptoms of asthmatics with high negative affectivity are more influenced by suggestion than those of patients with low negative affectivity.

Adult↗

PubMed2002

Learning subjective health complaints.

Symptom episodes often show a spatio-temporal structure, that is, they occur in a specific context for a certain duration. Repeated experiences may therefore be construed as associative learning trials, in which context elements are turned into predictive cues, triggering anticipatory processes conducive to subjective health complaints. A series of experiments, using inhalations of air enriched with CO2 and external (odors) or internal (mental images) stimuli as cues, is discussed to show that subjective health complaints may occur upon presenting the cue alone. Learned symptoms may be unrelated to bodily responses and easily generalize to new related cues. Better learning occurs to cues with a negative affective valence and in participants scoring high for negative affectivity. Our findings are relevant to the understanding of medically unexplained ("functional") syndromes and the poor relationship between objective and subjective health indicators in general.

Humans↗