Do pain expectancies cause pain in chronic low back patients? A clinical investigation

The present study investigated whether pain expectancies cause pain in chronic low back patients. Back patients (N = 29) were requested to perform four exercise bouts (two with each leg), each consisting of flexing and extending the knee three times at maximal force (Cybex 350 System). During each exercise bout the baseline pain, the expected pain and experienced pain were recorded. Patients also reported their experienced fear of further injury to the back. Furthermore, the peak force of both knee flexors and extensors was assessed. Although patients did expect a back pain increase during the first exercise bout with each leg, no evidence was found for the thesis that pain expectancies generate increases in subjective pain experiences. Instead, the reported pain expectancy was readily corrected during the next exercise bout, whereas the experienced pain remained unchanged. Furthermore, a high pain expectancy co-occurred with (1) a marginally significant fear of (re)injury, and (2) a significant lower peak torque of the knee flexors. These results are consistent with conditioning models which state that pain expectations are associated with a fear response and an urge to avoid the pain.     

On the costs and benefits of directing attention towards or away from threat-related stimuli: A classical conditioning experiment

In attentional bias modification programs, individuals are trained to attend away from threat in order to reduce emotional reactivity to stressful situations. However, attending towards threat is considered to be a prerequisite for fear reduction in other models of anxiety. We compared both views by manipulating attention towards or away from an acquired signal of threat. The strength of extinction and reacquisition was assessed with threat and US-expectancy ratings. We found more extinction in the attend towards threat group, compared to both the attend away from threat group and a control group in which attention was not manipulated. The results are in line with the Emotional Processing Theory and cognitive accounts of classical conditioning.     

Early Development of Head Movements Between Birth and 4 Months of Age: A Longitudinal Study

The control of head posture and movement play a significant role in the early development of motor skills. However, a detailed kinematic study charting this development is currently lacking. Hence, the authors performed a longitudinal study of 18 infants between birth and 4 months charting changes in head posture and movements when tracking a visual object. The results showed that beyond 2 months, the head was more often held at the body midline and this was accompanied by an increase in the number, extent, and speed of head movement. Further, it was found that head movements were organized into movement units. Movement units initially increased in number, but after 3 months decreased in number and increased in duration, especially after peak velocity. This more symmetrical profile velocity points to more controlled head movements after 3 months of age.     

Establishing normative data for repeated cognitive assessment: A comparison of different statistical methods

Serial cognitive assessment is conducted to monitor changes in the cognitive abilities of patients over time. At present, mainly the regression-based change and the ANCOVA approaches are used to establish normative data for serial cognitive assessment. These methods are straightforward, but they have some severe drawbacks. For example, they can only consider the data of two measurement occasions. In this article, we propose three alternative normative methods that are not hampered by these problems—that is, multivariate regression, the standard linear mixed model (LMM), and the linear mixed model combined with multiple imputation (LMM with MI) approaches. The multivariate regression method is primarily useful when a small number of repeated measurements are taken at fixed time points. When the data are more unbalanced, the standard LMM and the LMM with MI methods are more appropriate because they allow for a more adequate modeling of the covariance structure. The standard LMM has the advantage that it is easier to conduct and that it does not require a Monte Carlo component. The LMM with MI, on the other hand, has the advantage that it can flexibly deal with missing responses and missing covariate values at the same time. The different normative methods are illustrated on the basis of the data of a large longitudinal study in which a cognitive test (the Stroop Color Word Test) was administered at four measurement occasions (i.e., at baseline and 3, 6, and 12 years later). The results are discussed and suggestions for future research are provided.     

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.     

Walking and periventricular leukomalacia: locomotor characteristics and brain imaging (MRI)

The aim of the present study was to compare the walking abilities in infants with and without periventricular leukomalacia and to see whether the severity of the brain damage was related to locomotor outcome of the infants at 12 and 18 months. 47 newborns were included in the study based on white matter abnormalities on ultrasound. Magnetic resonance imaging (MRI) recordings during the neonatal period were used to identify and quantify the location and severity of the brain lesions. Locomotor outcome was assessed in terms of disability at 12 and 18 months. The quality of walking, including global and segmental gait parameters, was measured for the infants who could walk independently at 18 months and compared to a group of healthy control infants. The number of children who could walk was related to the extent of white matter abnormalities seen on the neonatal MRI, but the quality of walking was not.     

An empirical validation of a dynamic systems model of interaction: do children of different sociometric statuses differ in their dyadic play?

Studying short-term dynamic processes and change mechanisms in interaction yields important knowledge that contributes to understanding long-term social development of children. In order to get a grip on this short-term dynamics of interaction processes, the authors made a dynamic systems model of dyadic interaction of children during one play session. The control parameters of the model relate to children's goal-directedness, concerns, emotional appraisals, social power, and social competence. Three groups of dyads of different sociometric statuses are represented by specific control parameter values. The model's order parameters consist of children's emotional expressions and other- versus self-directed actions. This article describes the empirical validation of the model and the methods needed for such validation. It focuses on the model's predictions of averages and distributions of the major variables, of the occurrence of attractors and power law distributions, and on the model's sensitivity. Overall, the model fits the empirical data well. In the discussion, we reflect on the developmental and methodological implications for explaining social interaction on the short-term as well as on the long-term time scale. In addition, implications for intervention and assessment are presented, in particular relating to the problem of rejection.     

Risk Regulation, EU Law and Emerging Technologies: Smother or Smooth?

Risk analysis as a regulatory driver has now become firmly entrenched in public health and environmental protection. Risk analysis at any level essentially has to accommodate two gut feelings of the constituency: whether society should be risk-prone or risk averse, and whether government and its institutions can be trusted to make the necessary decisions with a high or a low degree of discretion. The precautionary principle (or rejection thereof) arguably is the ultimate reflection of the promotion of risk to a societal value. There is no doubt that especially amongst the representatives of the Member States (as opposed to the officials at the European Commission), public (pre)caution with respect to the long-term environmental and public health implications of gene technology influenced the reluctance to allow marketing of GM foods and feeds until a strict regulatory regime had been rolled out. Industry would argue that the delay in regulation, as well as the eventual regime was of such a nature as to stifle the technology. This contribution reviews a number of features of standard EU risk analysis decisions, so as to assess its current propensity towards smothering rather than smoothing the introduction of new technology. The current development of a regulatory framework for nanotechnology serves as a case study.