Anticipatory stress reduction among chronic pain patients

Effects of open and hidden administration of treatment-related information; a multi-experiment study

BACKGROUND

Two experiments (E1 and E2; N = 44 and N = 52, respectively) investigated the effect of positive (PI) and neutral information (NI) about a dental procedure, and if the delivery of the information by the treatment team (open administration) or unbeknownst to the treatment team (hidden administration), affected pain.

METHODS

Using a mixed design, patients undergoing drilling in a molar were randomized to the NI or PI groups. Before, during, and after treatment, patients reported their pain and stress levels. In E1 the treatment team delivered the information. In E2, an assistant not engaged in the treatment delivered the information.

RESULTS

In the PI group in E1, pain was reduced by 50 % compared to the NI group, and the effects of stress on pain were mitigated. These effects were abolished in E2. The dentist reported having displayed positive nonverbal behaviours (e.g. smiling and longer eye contact) in the PI group in E1, but not in E2.

DISCUSSION

Positive information reduced pain only when administrated openly. There was no effect of positive information administrated hidden from the treatment team. As information was similar in both experiments, factors other than the information most likely reduced pain in the PI group in E1.

CONCLUSION

Delivering positive information by the treatment team may generate behavioural cues which generate placebo effects.

The Influence of Stress and Anxiety on the Expectation, Perception and Memory of Dental Pain in Schoolchildren

The aim of this study was to investigate the association of stress and anxiety with the expectation, perception and memory of dental pain among schoolchildren. A follow-up study involving 46 children aged 9 to 12 years was conducted in a public school in the city of Petropolis (RJ), Brazil. Demographic characteristics, stress (children's stress scale), and state and trait anxiety (state⁻trait anxiety inventory) were recorded before a dental procedure to restore the occlusal surface of a permanent first molar under local anaesthetic. Dental pain was assessed using the faces pain scale before (dental pain expectation), immediately after (dental pain perception) and six weeks after (memory of dental pain) the dental procedure. Dental pain expectation scores were significantly higher than dental pain perception, independent of the levels of stress, state anxiety and trait anxiety. Children with high scores of stress (OR 1.05 95%CI 1.02⁻1.09), state anxiety (OR 1.15 95%CI 1.05⁻1.27) and trait anxiety (OR 1.18 95%CI 1.07⁻1.30) were more likely to report greater scores of dental pain expectation. Children anticipated more dental pain than what was actually perceived after the dental restoration. Children with greater levels of stress and anxiety have a distorted evaluation of expected dental pain before the dental procedure.

Cortical EEG alpha rhythms reflect task-specific somatosensory and motor interactions in humans

Anticipating sensorimotor events allows adaptive reactions to environment with crucial implications for self-protection and survival. Here we review several studies of our group that aimed to test the hypothesis that the cortical processes preparing the elaboration of sensorimotor interaction is reflected by the reduction of anticipatory electroencephalographic alpha power (about 8-12Hz; event-related desynchronization, ERD), as an index that regulate task-specific sensorimotor processes, accounted by high-alpha sub-band (10-12Hz), rather than a general tonic alertness, accounted by low-alpha sub-band (8-10Hz). In this line, we propose a model for human cortical processes anticipating warned sensorimotor interactions. Overall, we reported a stronger high-alpha ERD before painful than non-painful somatosensory stimuli that is also predictive of the subjective evaluation of pain intensity. Furthermore, we showed that anticipatory high-alpha ERD increased before sensorimotor interactions between non-painful or painful stimuli and motor demands involving opposite hands. In contrast, sensorimotor interactions between painful somatosensory and sensorimotor demands involving the same hand decreased anticipatory high-alpha ERD, due to a sort of sensorimotor "gating" effect. In conclusion, we suggest that anticipatory cortical high-alpha rhythms reflect the central interference and/or integration of ascending (sensory) and descending (motor) signals relative to one or two hands before non-painful and painful sensorimotor interactions.

Distraction affects frontal alpha rhythms related to expectancy of pain: An EEG study

Previous electroencephalographic (EEG) evidence has shown event-related desynchronization (ERD) of alpha rhythms before predictable painful stimuli, as a possible neural concomitant of attentional preparatory processes (Babiloni, C., Brancucci, A., Babiloni, F., Capotosto, P., Carducci, F., Cincotti, F., Arendt-Nielsen, L., Chen, A.C., Rossini, P.M., 2003. Anticipatory cortical responses during the expectancy of a predictable painful stimulation. A high-resolution electroencephalography study. Eur. J. Neurosci. 18 (6) 1692-700). This study tested the hypothesis that alpha ERD before predictable painful stimuli is reduced as an effect of distraction. A visual warning stimulus preceded a laser painful stimulation, which was strictly followed by visual imperative stimuli. In the Pain (control) condition, no task was required after the imperative stimuli. In the Pain + Movement condition, subjects had to perform a movement of the right index finger. In the Pain + Cognition condition, they had to mentally perform an arithmetical task. EEG data were recorded in 10 subjects from 30 electrodes. Artifact-free recordings were spatially enhanced by surface Laplacian transformation. Alpha ERD was computed at three alpha sub-bands according to subjects' individual alpha frequency peak (i.e., about 6-8 Hz, 8-10 Hz, 10-12 Hz). Compared to the control condition, the subjects reported a significantly lower stimulus intensity perception and unpleasantness in the Pain + Movement and Pain + Cognition conditions. In addition, there was a cancellation of the alpha 3 ERD (i.e., about 10-12 Hz) in Pain + Cognition condition and even a generation of a statistically significant alpha 3 ERS in Pain + Movement condition. These effects were maximum over fronto-central midline. These results suggest that distraction during the expectancy of pain is related to a reduced neural desynchronization of fronto-central midline alpha rhythms (i.e., reduced cortical activation) towards an overt hyper-synchronization (cortical idling).

Expectancy of Pain Is Influenced by Motor Preparation: A High-Resolution EEG Study of Cortical Alpha Rhythms

This high-resolution electroencephalographic (EEG) study on alpha event-related desynchronization (ERD) evaluated whether anticipatory activity precedes a sensorimotor interaction induced by concomitant painful stimuli and sensorimotor demand. An omitted-stimulus paradigm induced the expectancy of the painful stimulation at the left hand. In the experimental condition, the painful stimulation was associated with a visual go/no-go task triggering right-hand movements. Two control conditions manipulated the painful sensorimotor interaction variable. Compared with the control conditions, the expectancy of the painful sensorimotor interaction increased the high-band alpha EEG oscillations over the right primary sensorimotor cortex contralateral to the nociceptive stimuli and, to a lesser extent, over the centroparietal midline. These findings suggest that concomitant painful stimuli and simple sensorimotor go/no-go demands affect anticipatory activity as revealed by alpha ERD.

Contingent Negative Variation in the Parasylvian Cortex Increases During Expectancy of Painful Sensorimotor Events: A Magnetoencephalographic Study

Previous evidence relating to somatosensory-evoked magnetic fields has shown that the human parasylvian cortex (PC) is affected by ongoing painful sensorimotor interactions. In the present magnetoencephalographic study, the activity of the PC was investigated to evaluate the hypothesis of anticipatory processes preceding painful sensorimotor interactions. Sensorimotor interactions were induced by warned painful electrical stimulations at the left hand concomitant with a motor task of the right hand. The anticipatory activity of the PC was probed via contingent negative variation. Compared with the control nonpainful condition, the anticipation of the painful sensorimotor interactions increased the PC activity over the hemisphere ipsilateral to the stimulation. Dipole modeling indicated that the center of gravity of the anticipatory activity in the PC was located in the secondary somatosensory cortex. These results suggest that anticipation of painful sensorimotor interactions engages the human PC, especially in the hemisphere ipsilateral to upcoming painful stimuli and contralateral to preparatory motor commands.

Testing a theory of chronic pain

BACKGROUND

Chronic pain is highly prevalent among older people with arthritis, with depression as its major outcome. The psychopathological process of chronic pain and its outcomes in older people with arthritis have not been the subject of extensive research. The purpose of this study was to test a middle-range theory of chronic pain derived from the Roy Adaptation Model, a nursing theory whose validity has not been tested in the context of chronic pain.

METHODS

The study used a convenience sample of 71 older people with arthritis. Two subscales of the Arthritis Impact Measurement Scales were used to measure pain and physical disability. Social support was measured by Part II of the Personal Resource Questionnaire, and the Elderly Daily Stress scale was used to measure daily stress. Participants also completed the 10-item Center for Epidemiological Studies of Depression scale. Univariate analysis, correlation, and path analysis were used to analyse the data.

RESULTS

Overall, the data supported the hypothesized model in which pain, disability, social support, age, and gender are predictors of daily stress and daily stress further predicts depression. The direct effects of chronic pain, disability, and social support accounted for 37% of the variance of daily stress, which in turn predicted 35% of the variance of depression. Age and gender had no influence on daily stress. The chi-square index suggested a fit between the data and the model, and therefore the current model is temporarily accepted. Other fit indices also showed a good fit of the model to the data. To simplify the model, a revised version was developed.

CONCLUSIONS

This study validated a middle-range theory to explain the effects of chronic pain in older people with arthritis and highlights the importance of chronic pain in the development of depression.