Relationship between anxiety and dyspnea on exertion in patients with chronic obstructive pulmonary disease

Abstract

Dyspnea limits exercise in patients with chronic obstructive pulmonary disease (COPD) and is known to induce anxiety. Little is known whether anxiety contributes to exercise-induced dyspnea, which in turn might influence the outcome of diagnostic tests. The aim of the present study was to examine the relationship between general anxiety and dyspnea on exertion in patients with COPD.

Ninety patients with stable COPD participated; 44 men, mean age 61 (standard deviation (SD) 10.4), and mean forced expiratory volume in 1 second (%pred.) 40.5 (SD 16.9). All participants performed pulmonary function tests and an incremental cycle ergometry. The Modified Borg Scale was used to measure the level of dyspnea on exertion. Anxiety symptoms were assessed with the Hospital Anxiety and Depression Scale. Data were analyzed using Spearman's correlations and multivariate regression. Dyspnea on exertion was correlated with general anxiety (r=.31), age (r=–.30), and exercise capacity (r=.27). Regression analysis showed that general anxiety was associated with dyspnea on exertion, adjusted for sex, age, baseline dyspnea, and exercise capacity. Consequently, it is reasoned that results of exercise training and activities in daily living may be influenced negatively by anxiety-worsened dyspnea. Attention should be given to anxiety management in patients with COPD to optimize exercise training.     

Rapid Integration of Contour Fragments: From Simple Filling-in to Parts-based Shape Description

Line drawings are easy to recognize, although the only information to the visual system is the contour itself. Starting from information theory and a theory of decomposition in parts, we investigated whether certain regions of such a contour are perceptually more relevant than others, using a deletion detection paradigm. In this paradigm, high detectability means poor contour integration, and vice versa. Regions of interest were curvature singularities, namely positive maxima (M+), negative minima (m?) and inflection points (I), of smooth, closed contours. In Experiment 1, we performed a first exploration of the detectability of deletions around these three types of curvature singularities. M+ deletions were easier to detect than the deletions around the other two singularities, a result that is explained using a post hoc combination of both mentioned theoretical frameworks. In Experiment 2, we replicated these findings using figure-background reversal, so thatthe same physical deletions could either be M+ or m?. Again, the M+ deletions were easier to detect than m? deletions. Although both types of singularities involve regions of high curvature changes, they differ in that mdeletions create gaps that concur with spontaneous segmentation.     

Continuous time modelling with individually varying time intervals for oscillating and non‐oscillating processes

When designing longitudinal studies, researchers often aim at equal intervals. In practice, however, this goal is hardly ever met, with different time intervals between assessment waves and different time intervals between individuals being more the rule than the exception. One of the reasons for the introduction of continuous time models by means of structural equation modelling has been to deal with irregularly spaced assessment waves (e.g., Oud & Delsing, 2010). In the present paper we extend the approach to individually varying time intervals for oscillating and non‐oscillating processes. In addition, we show not only that equal intervals are unnecessary but also that it can be advantageous to use unequal sampling intervals, in particular when the sampling rate is low. Two examples are provided to support our arguments. In the first example we compare a continuous time model of a bivariate coupled process with varying time intervals to a standard discrete time model to illustrate the importance of accounting for the exact time intervals. In the second example the effect of different sampling intervals on estimating a damped linear oscillator is investigated by means of a Monte Carlo simulation. We conclude that it is important to account for individually varying time intervals, and encourage researchers to conceive of longitudinal studies with different time intervals within and between individuals as an opportunity rather than a problem.     

Filial imprinting and associative learning

Evidence is reviewed that is relevant to an interpretation of filial imprinting as a form of classical or Pavlovian conditioning. For such an interpretation it has to be assumed that the imprinting object provides both the unconditioned stimulus (UCS) and the conditioned stimulus (CS). The difficulty for an experimental approach is that CS and UCS are always presented simultaneously and cannot be manipulated independently, making it virtually impossible to test phenomena such as latent inhibition and extinction. Existing evidence is consistent with a conditioning theory of imprinting, for instance with regard to the reversibility of filial preferences. Some hitherto unexplained findings can be accounted for in terms of overshadowing and blocking. Results of an experiment are discussed in which the occurrence of blocking was explicitly tested. The findings support an associative learning interpretation of imprinting, but further experiments are needed to be able to rule cut alternative explanations.     

Exposure to physical movements in low back pain patients: restricted effects of generalization.

Whether the effects of exposure to 1 movement generalize to another dissimilar movement was investigated in 37 patients with low back pain (15 men, 22 women). Two movements were executed twice: bending forward while standing and lifting 1 leg while lying down. During each trial, baseline pain, expected pain, and experienced pain were recorded. Similar ratings for perceived harm were obtained. Analyses revealed an initial over prediction of pain, but after exposure the overprediction was readily corrected. This exposure effect did not generalize toward another dissimilar movement. These results were only characteristic for patients with catastrophic thinking about pain. Low pain catastrophizers did not overpredict pain. There were no effects of exposure on perceived harm. Exposure may profitably be conceived of as the learning of exceptions to a general rule.     

Faster forgetting contributes to impaired spatial memory in the PDAPP mouse: Deficit in memory retrieval associated with increased sensitivity to interference?

Two experiments were conducted to investigate the possibility of faster forgetting by PDAPP mice (a well-established model of Alzheimer's disease as reported by Games and colleagues in an earlier paper). Experiment 1, using mice aged 13-16 mo, confirmed the presence of a deficit in a spatial reference memory task in the water maze by hemizygous PDAPP mice relative to littermate controls. However, after overtraining to a criterion of equivalent navigational performance, a series of memory retention tests revealed faster forgetting in the PDAPP group. Very limited retraining was sufficient to reinstate good memory in both groups, indicating that their faster forgetting may be due to retrieval failure rather than trace decay. In Experiment 2, 6-mo-old PDAPP and controls were required to learn each of a series of spatial locations to criterion with their memory assessed 10 min after learning each location. No memory deficit was apparent in the PDAPP mice initially, but a deficit built up through the series of locations suggestive of increased sensitivity to interference. Faster forgetting and increased interference may each reflect a difficulty in accessing memory traces. This interpretation of one aspect of the cognitive deficit in human mutant APP mice has parallels to deficits observed in patients with Alzheimer's disease, further supporting the validity of transgenic models of the disease.     

Contour-based object identification and segmentation: stimuli, norms and data, and software tools.

We summarize five studies of our large-scale research program, in which we examined aspects of contour-based object identification and segmentation, and we report on the stimuli we used, the norms and data we collected, and the software tools we developed. The stimuli were outlines derived from the standard set of line drawings of everyday objects by Snodgrass and Vanderwart (1980). We used contour curvature as a major variable in all the studies. The total number of 1,500 participants produced very solid, normative identification rates of silhouettes and contours, straight-line versions, and fragmented versions, and quite reliable benchmark data about saliency of points and object segmentation into parts. We also developed several software tools to generate stimuli and to analyze the data in nonstandard ways. Our stimuli, norms and data, and software tools have great potential for further exploration of factors influencing contour-based object identification, and are also useful for researchers in many different disciplines (including computer vision) on a wide variety of research topics (e.g., priming, agnosia, perceptual organization, and picture naming). The full set of norms, data, and stimuli may be downloaded from www.psychonomic.org/archive/.     

What is “marked” in visual marking? evidence for effects of configuration in preview search

Visual search for a conjunction target is facilitated when distractor sets are segmented over time: the preview benefit. Watson and Humphreys (1997) suggested that this benefit involved inhibition of old items (visual marking, VM). We investigated whether the preview benefit is sensitive to the configuration of the old distractors. Old distractors changed their location prior to the occurrence of the new items, while also either changing or maintaining their configuration. Configuration changes disrupted search. The results are consistent with object-based VM, which is sensitive to the configuration of old stimuli.