Retrospective memory for symptoms in patients with medically unexplained symptoms.

OBJECTIVE: Clinical assessment and diagnostic processes heavily rely on memory-based symptom reports. The current study investigated memory for symptoms and the peak-end effect for dyspnea in patients with medically unexplained symptoms and healthy participants. METHODS: Female patients with medically unexplained dyspnea (MUD) (n=22) and matched healthy controls (n=22) participated in two dyspnea induction trials (short, long). Dyspnea ratings were collected: (1) continuously during symptom induction (concurrent with respiratory measures), (2) immediately after the experiment, and (3) after 2weeks. Symptoms, negative affect, and anxiety were assessed at baseline and after every trial. The mediating role of state anxiety in symptom reporting was assessed. The peak-end effect was tested with forced-choice questions measuring relative preference for the trials. RESULTS: Compared to controls, dyspnea induction resulted in higher levels of symptoms, anxiety, concurrent dyspnea ratings, and minute ventilation in the patient group. In both groups, immediate retrospective ratings were higher than averaged concurrent ratings. No further increase in dyspnea ratings was observed at 2-week recall. Retrospective dyspnea ratings were mediated by both state anxiety and concurrent dyspnea ratings. Patients did not show a peak-end effect, whereas controls did. CONCLUSION: The findings show that patients' experience of a dyspneic episode is subject to immediate memory bias, but does not change over a longer time period. The results also highlight the importance of affective state during symptom experience for both symptom perception and memory.

Peak-end memory bias in laboratory-induced dyspnea: a comparison of patients with medically unexplained symptoms and healthy controls.

OBJECTIVE: Memory for unpleasant experiences is dominated by intensity at the experience's peak and end, with a relative neglect for its duration. Therefore, unpleasant somatic experiences are expected be remembered as less aversive when they end gradually rather than abruptly, even when they last longer (i.e., the "peak-end effect"). We investigated the peak-end effect for dyspnea in healthy participants and in patients with medically unexplained dyspnea (MUD). METHODS: Two aversive dyspnea-inducing tasks were administered to a clinical MUD sample (n = 29) and a matched healthy control group (n = 29) using a rebreathing paradigm (60-second room air, 150-second rebreathing). In a short trial, the breathing system (mouthpiece) was removed immediately after peak dyspnea. In a long trial, breathing was switched to room air after peak dyspnea and continued in the breathing system for 150 seconds (order was counterbalanced across participants). Respiratory parameters were continuously measured, and dyspnea was rated every 10 seconds. Relative unpleasantness of the dyspneic episode was assessed with forced choice questions. RESULTS: More than 70% of the healthy group found the short episode worse than the long one despite equal maximal dyspnea (p = .02). Patients with MUD did not show this peak-end effect (p = .58). The latter had deficient recovery of dyspnea compared with the controls (42.08 [21.86] versus 17.51 [11.18], p < .001), which could not be explained by differences in respiratory physiology. CONCLUSIONS: The peak-end effect in dyspnea has important implications for dyspnea measurement. Its absence in patients with MUD suggests a critical role of distorted perceptual-cognitive processing of aversive somatic sensations in patients with medically unexplained symptoms.

Sensitization in medically unexplained dyspnea: differential effects on intensity and unpleasantness.

BACKGROUND: The present study investigated alterations in both the sensory (intensity) and the affective (unpleasantness) components of dyspnea in patients with medically unexplained dyspnea during repeated hypercapnic challenges. METHODS: The sensory and affective components were assessed every 20 s during the baseline, rebreathing, and recovery phases of three subsequent trials in patients (n = 17) and matched healthy control subjects (n = 5). Fractional end-tidal carbon dioxide was monitored simultaneously and continuously. Peak intensity and unpleasantness were compared, and intraindividual linear regression slopes between the dyspnea components and fractional end-tidal carbon dioxide were calculated. RESULTS: Both intensity and unpleasantness of dyspnea perception were higher in patients than in healthy control subjects. Additionally, the regression slopes were steeper, but this was more prominent for the affective than for the sensory component in patients. Moreover, across-trial increases in unpleasantness of peak dyspnea and slopes of both components were observed in patients. CONCLUSIONS: Patients with medically unexplained dyspnea are particularly hypersensitive to the unpleasantness of dyspnea. The elevated breathlessness further increases across repeated challenges, documenting sensitization and suggesting that basic learning mechanisms contribute to exaggerated response to respiratory challenges.

Dyspnea perception in COPD: association between anxiety, dyspnea-related fear, and dyspnea in a pulmonary rehabilitation program.

BACKGROUND: A growing body of research connects anxiety with poorer outcomes in COPD. However, more specific measures of dyspnea-related fear may be more closely related to critical processes involved in pulmonary rehabilitation (perception of dyspnea and avoidance of physical activity) and may have a predictive value for COPD outcome beyond general anxiety measures. METHODS: In this naturalistic outcome study, we investigated the effects of baseline anxiety and dyspnea-related fear on perceived dyspnea and other outcomes of a well-established pulmonary rehabilitation program for COPD. RESULTS: Seventy-three patients participated in the study. At baseline, higher dyspnea-related fear was associated with higher levels of dyspnea during ergometer exercise, but also with a steeper decrease of exercise dyspnea during the course of pulmonary rehabilitation, whereas lower dyspnea-related fear was associated with an increase in exercise dyspnea, even when controlling for anxiety, lung function, and exercise intensity. Furthermore, higher dyspnea-related fear was associated with reduced quality of life (mastery subscale) and maximal exercise capacity at baseline, but also with a steeper increase in quality of life (emotions and mastery subscale) and exercise capacity during rehabilitation. However, the association of dyspnea-related fear with worse 6-min walking distance and impairment in daily activities persisted throughout rehabilitation. CONCLUSIONS: Results indicate a mediating effect of dyspnea-related fear on the association between anxiety and exercise-related dyspnea. Exercise in pulmonary rehabilitation in people with higher baseline dyspnea-related fear may act as a correction of excessive symptom reports through exposure to dyspneic situations.

Dyspnea-related anxiety: The Dutch version of the Breathlessness Beliefs Questionnaire.

Dyspnea-related anxiety may lead to reduced quality of life and functional disability through fearful avoidance of dyspnea-evoking activity. We describe the validation of a generic - diagnosis-independent - instrument assessing dyspnea-related anxiety. A total of 187 patients with respiratory diseases completed the Breathlessness Beliefs Questionnaire (BBQ), a 17-item questionnaire adapted from the Tampa Scale for Kinesiophobia (TSK), a measure of how harmful pain patients think painful movement is and to what extent they think activity should be avoided. Measures of negative and positive affectivity (PANAS), anxiety and depression (HADS), functional status (PFSDQ), and health-related quality of life (CRDQ) were also completed. Principal component analysis and item-total correlations suggested a reliable (reduced) 11-item BBQ (Cronbach's alpha = .85) with two factors converging with the TSK factors: a 'somatic focus' factor assessing the harmfulness of dyspnea and the underlying pathology and an 'activity avoidance' factor assessing beliefs that activity should be avoided. Correlational analyses support the construct validity of the BBQ: higher scores on the BBQ are associated with reduced health-related quality of life and functional status. Associations between 'somatic focus' and negative affectivity and anxiety and between 'activity avoidance' and positive affectivity and depression further supported the validity of the BBQ and its subscales. The BBQ is a valid, short, and useful instrument to assess respiratory patients' beliefs about the harmfulness of their disease and physical activities. Further research is needed to document to what extent BBQ scores are related to daily life activities and symptoms.

Distorted symptom perception in patients with medically unexplained symptoms.

The present study investigated differences in symptom perception between a clinical sample with medically unexplained symptoms (MUS) and a matched healthy control group. Participants (N = 58, 29 patients) were told that they would inhale different gas mixtures that might induce symptoms. Next, they went through 2 subsequent rebreathing trials consisting of a baseline (60 s room air breathing), a rebreathing phase (150 s, which gradually increased ventilation, PCO2 in the blood, and perceived dyspnea), and a recovery phase (150 s, returning to room air breathing). Breathing behavior was continuously monitored, and dyspnea was rated every 10 s. The within-subject correlations between dyspnea on the one hand and end-tidal CO2 and minute ventilation on the other were used to index the degree to which perceived dyspnea was related to specific relevant respiratory changes. The results showed that perceived symptoms were less strongly related to relevant physiological parameters in MUS patients than in healthy persons, specifically when afferent physiological input was relatively weak. This suggests a stronger role for top-down psychological processes in the symptom perception of patients with MUS.

Is there a link between 'pain-proneness' and 'action-proneness'?

The present study was designed to examine the premorbid 'action-proneness' of chronic pain patients without obvious organic etiology. Using a validated psychometric instrument (the HAB questionnaire), 3 clinical groups were compared: 30 patients with chronic 'non-organic' pain, 30 patients with chronic organic pathology and 30 hospitalized psychiatric patients without pain as a primary complaint. The results indicate that the chronic pain patients describe themselves retrospectively as more 'action-prone' than the patients of the two control groups. Using an analysis of covariance to have statistical control on age, occupational level and depression, the results were statistically significant on the 0.05 level. Although this study suggests that a strong tendency towards direct action may be a frequent and relatively specific premorbid feature of chronic pain patients, the pathogenic implications of these findings remain uncertain.