Counterirritation by pain inhibits the responsiveness to aversive loud tones: the role of state anxiety and state fear triggered in the NPU paradigm.

AIM OF THE STUDY: The application of a noxious stimulus reduces the perception and responsiveness to other pain stimuli. This inhibition can be experimentally assessed with a method called 'counterirritation'. The question arises if counterirritation acts also on the perception and responsiveness to aversive but non-nociceptive stimuli (e.g., loud tones). Since aversive stimulation is often associated with state anxiety or state fear, we investigated in addition the modulatory effects of these emotions on counterirritation. MATERIAL AND METHODS: 51 subjects participated in our study. We presented tones with aversive loudness (105 dB), first alone then during counterirritation (immersion of the hand in a hot water bath of 46 °C) to assess inhibition of loudness perception and responsiveness. Influences of state anxiety and state fear on counterirritation were investigated by using the Neutral-Predictable(fear)- Unpredictable(anxiety) Paradigm (NPU), which is based on classical conditioning. Loudness ratings (perception of the aversive tones) and startle reflex (defensive reaction to aversive tones) were assessed. RESULTS: Counterirritation reduced startle reflex amplitudes, but not the loudness ratings. Although state anxiety and state fear were successfully induced, counterirritation remained unaffected. CONCLUSIONS: Our study showed that pain inhibits the responsiveness to aversive stimuli (loud tones). Thus, the postulate that 'pain inhibits pain' might be better changed to 'pain inhibits aversiveness'. Consequently, our findings may also question the assumption of a clear pain specificity in inhibitory action as assumed by theoretical approaches like 'conditioned pain modulation' (CPM). Furthermore, counterirritation appeared one more time resistant to the influence of negative emotions.

Brain mechanisms associated with facial encoding of affective states.

Affective states are typically accompanied by facial expressions, but these behavioral manifestations are highly variable. Even highly arousing and negative valent experiences, such as pain, show great instability in facial affect encoding. The present study investigated which neural mechanisms are associated with variations in facial affect encoding by focusing on facial encoding of sustained pain experiences. Facial expressions, pain ratings, and brain activity (BOLD-fMRI) during tonic heat pain were recorded in 27 healthy participants. We analyzed facial expressions by using the Facial Action Coding System (FACS) and examined brain activations during epochs of painful stimulation that were accompanied by facial expressions of pain. Epochs of facial expressions of pain were coupled with activity increase in motor areas (M1, premotor and SMA) as well as in areas involved in nociceptive processing, including primary and secondary somatosensory cortex, posterior and anterior insula, and the anterior part of the mid-cingulate cortex. In contrast, prefrontal structures (ventrolateral and medial prefrontal) were less activated during incidences of facial expressions, consistent with a role in down-regulating facial displays. These results indicate that incidences of facial encoding of pain reflect activity within nociceptive pathways interacting or possibly competing with prefrontal inhibitory systems that gate the level of expressiveness.

Optimism and the Experience of Pain: A Systematic Review.

A growing body of literature provides evidence of the health-promoting effects of optimism, including its protective role in acute and chronic pain. Optimists are characterized by positive expectations concerning the future. These positive outcome expectancies lead to more and longer goal-directed efforts and the use of approach coping strategies. No systematic review on the effects of optimism on the experience of pain has so far been conducted. A search in the databases PubMed, Web of Science and PsycInfo, and the scanning of reference lists identified 69 eligible studies. These were categorized according to sample size, participants' age and sex, design, optimism-pain relation as primary vs. secondary study objective, and level of study/publication quality. Overall percentages of positive, zero, and negative associations between optimism and pain as well as relative frequencies of these associations in the different categories were analyzed. About 70% of the studies showed a positive, i.e., beneficial association between optimism and at least one pain outcome. A larger percentage of beneficial associations was found in studies with experimental designs, in studies with the optimism-pain relation as primary objective, in high-quality studies/publications, and in studies including participants with a higher average age. The review suggests that optimism is associated with less acute and chronic pain, especially since a higher percentage of beneficial associations was found with high study/publication quality and with the primary focus on this relationship. For the moderating role of age, different explanations are proposed. Further research on causal relationships and on optimism-fostering clinical interventions is needed.

[Assessing pain in patients with dementia]. / Schmerzerfassung bei Patienten mit Demenz.

The diagnostics of pain in older people with cognitive impairments should always consist of a subjective self-report of pain and a structured observation of pain behavior. It is important to note that the subjective self-report of pain becomes less valid with increasing cognitive decline (starting with a moderate degree of dementia). The external observation of pain behavior should include at least the three behavioral domains facial expressions, body movements and vocalization and should be performed during resting situations and during activities of daily living. Moreover, the patient should be observed for at least 3 min. Online forms of training have recently been developed and are freely available for training in external observation.

Does EEG activity during painful stimulation mirror more closely the noxious stimulus intensity or the subjective pain sensation?

BACKGROUND: Many researchers have tried to investigate pain by studying brain responses. One method used to investigate pain-related brain responses is continuous electroencephalography (EEG). The objective of the current study is to add on to our understanding of EEG responses during pain, by differentiation between EEG patterns indicative of (i) the noxious stimulus intensity and (ii) the subjective pain sensation. METHODS: EEG was recorded during the administration of tonic experimental pain, consisting of six minutes of contact heat applied to the leg via a thermode. Two stimuli above pain threshold, one at pain threshold and two non-painful stimuli were administered. Thirty-six healthy participants provided a subjective pain rating during thermal stimulation. Relative EEG power was calculated for the frequency bands alpha1, alpha2, beta1, beta2, delta, and theta. RESULTS: Whereas EEG activity could not be predicted by stimulus intensity (except in one frequency band), subjective pain sensation could significantly predict differences in EEG activity in several frequency bands. An increase in the subjective pain sensation was associated with a decrease in alpha2, beta1, beta2 as well as in theta activity across the midline electrodes. CONCLUSION: The subjective experience of pain seems to capture unique variance in EEG activity above and beyond what is captured by noxious stimulus intensity.

Using observational facial descriptors to infer pain in persons with and without dementia.

BACKGROUND: For patients with advanced dementia, pain diagnosis and assessment requires observations of pain-indicative behavior by others. One type of behavior that has been shown to be a promising candidate is the facial response to pain. To further test how pain-indicative facial responses are, we investigated the predictive power of observational facial descriptors to (i) predict the self-report of pain and (ii) to differentiate between non-painful and painful conditions. In addition, the expertise of the observers (nurses vs. healthy controls) and the cognitive status of the observed (dementia vs. cognitively healthy) were considered. METHODS: Overall 62 participants (32 nurses and 30 control subjects) watched 40 video-clips, showing facial expressions of older individuals with and without dementia during non-painful and painful pressure stimulation. After each clip, participants were asked to rate the videos using commonly used facial descriptors of pain and also to provide global pain estimate ratings of how much pain the observed individual might have experienced. RESULTS: Out of the 12 facial descriptors used, only 7 were able to differentiate between non-painful and painful conditions. Moreover, participants were better in predicting the pain self-report of the observed individuals when using facial descriptors than when using global pain estimates. Especially, the anatomically-orienting descriptors (e.g. opened mouth, narrowing eyes) showed greatest predictive power. Results were not affected by pain-expertise of the observers (nurses vs. control subjects) or diagnostic status of the observed (patients with dementia vs. cognitively unimpaired subjects). CONCLUSIONS: The fine-grained and specific observation of facial responses to acute pain appeared to provide valid indication of pain that is not compromised when patients with dementia are observed. The regular professional training does not put nurses at advantage to detect pain via facial responses.

Which Facial Descriptors Do Care Home Nurses Use to Infer Whether a Person with Dementia Is in Pain?

OBJECTIVES: Pain assessment in people with advanced dementia relies strongly on observable pain behaviors, such as facial expressions, body movement, and vocalizations. However, the process of inferring pain in others based on such observations is not well understood. We aimed to investigate which features of facial expressions caregivers rely on when inferring the presence and intensity of pain in people with dementia. METHODS: A questionnaire, including items on 13 facial descriptors, which were extracted from established observational scales for pain in dementia, was sent to 366 nursing homes in Germany. We asked the nurses to observe patients with dementia and then rate their observations using the facial descriptors, as well as to provide an overall pain estimate of the residents' pain. We used regression analyses to identify which facial descriptors nurses use most commonly to infer whether a person with dementia is in pain and to grade the pain's intensity. RESULTS: Seventy-nine nursing homes participated (22% response rate), and a total of 284 completed observer ratings were returned. The observed individuals suffered from moderate to severe dementia and were observed in everyday care situations. The average pain estimated by the caregivers was slight to moderate. Mainly anatomically based descriptors ("frowning," "narrowed eyes") and indicators of emotional arousal ("looking tense," looking frightened") significantly predicted the overall pain ratings by nurses, explaining approximately 45% of the variance. CONCLUSIONS: Although all presented facial descriptors were used by the nurses, some descriptors were used clearly more frequently than others to infer whether a resident with dementia was in pain. Development of observational pain tools and training in their use should consider the preexisting assumptions that nurses use to infer pain as well as their potential bias.

Problems of video-based pain detection in patients with dementia: a road map to an interdisciplinary solution.

BACKGROUND: Given the unreliable self-report in patients with dementia, pain assessment should also rely on the observation of pain behaviors, such as facial expressions. Ideal observers should be well trained and should observe the patient continuously in order to pick up any pain-indicative behavior; which are requisitions beyond realistic possibilities of pain care. Therefore, the need for video-based pain detection systems has been repeatedly voiced. Such systems would allow for constant monitoring of pain behaviors and thereby allow for a timely adjustment of pain management in these fragile patients, who are often undertreated for pain. METHODS: In this road map paper we describe an interdisciplinary approach to develop such a video-based pain detection system. The development starts with the selection of appropriate video material of people in pain as well as the development of technical methods to capture their faces. Furthermore, single facial motions are automatically extracted according to an international coding system. Computer algorithms are trained to detect the combination and timing of those motions, which are pain-indicative. RESULTS/CONCLUSION: We hope to encourage colleagues to join forces and to inform end-users about an imminent solution of a pressing pain-care problem. For the near future, implementation of such systems can be foreseen to monitor immobile patients in intensive and postoperative care situations.

Lack of predictive power of trait fear and anxiety for conditioned pain modulation (CPM).

In recent years the association of conditioned pain modulation (CPM) with trait fear and anxiety has become a hot topic in pain research due to the assumption that such variables may explain the low CPM efficiency in some individuals. However, empirical evidence concerning this association is still equivocal. Our study is the first to investigate the predictive power of fear and anxiety for CPM by using a well-established psycho-physiological measure of trait fear, i.e. startle potentiation, in addition to two self-report measures of pain-related trait anxiety. Forty healthy, pain-free participants (female: N = 20; age: M = 23.62 years) underwent two experimental blocks in counter-balanced order: (1) a startle paradigm with affective picture presentation and (2) a CPM procedure with hot water as conditioning stimulus (CS) and contact heat as test stimulus (TS). At the end of the experimental session, pain catastrophizing (PCS) and pain anxiety (PASS) were assessed. PCS score, PASS score and startle potentiation to threatening pictures were entered as predictors in a linear regression model with CPM magnitude as criterion. We were able to show an inhibitory CPM effect in our sample: pain ratings of the heat stimuli were significantly reduced during hot water immersion. However, CPM was neither predicted by self-report of pain-related anxiety nor by startle potentiation as psycho-physiological measure of trait fear. These results corroborate previous negative findings concerning the association between trait fear/anxiety and CPM efficiency and suggest that shifting the focus from trait to state measures might be promising.

Age Differences in Decoding Pain from the Facial Expression of Healthy Individuals and Patients with Dementia.

OBJECTIVE: Patients with dementia, whose ability to provide self-report of pain is often impaired, are in crucial need of observers who can detect the patients' pain-indicative behaviors appropriately, to initiate treatment. The facial display of pain promises to be especially informative for that purpose. The age of the observer has been shown to have a critical influence on observational emotion recognition (with age-related decrements in facial emotion recognition) but has not yet been studied as such for pain recognition. METHODS: For that purpose, 24 young (mean age: 24 years) and 22 older (mean age: 70 years) observers watched 120 video clips, showing facial expressions of young and old individuals with and without dementia during slight and moderate noxious stimulation. After each clip, observers were asked to rate how much pain the observed individual might have experienced. RESULTS: Young observers were superior in grading different levels of pain in the observed individuals; furthermore, their ratings corresponded better with the self-ratings of the observed individuals. However, the performance of the older observers was still sufficient as regards the differentiation of different pain levels and prediction of self-report in others. CONCLUSIONS: Age does not only lead to a decline in recognition of facial expressions of emotions but age also affects the quality of observational pain recognition in others. However, given that older observers' performance was only slightly reduced, clearly suggests that older caregivers are surely not at risk of becoming visual agnostic for the pain in others.

Cognitive remediation for depressed inpatients: Results of a pilot randomized controlled trial.

OBJECTIVE: Neurocognitive deficits that persist despite antidepressive treatment and affect social and vocational functioning are well documented in major depressive disorder. Cognitive training approaches have proven successful in ameliorating these deficits in other psychiatric groups, but very few studies have been conducted in unipolar depressive patients by now. In contrast to previous studies solely including outpatients, effects of a cognitive remediation intervention on neurocognitive functioning of depressed inpatients were assessed by the present study. METHOD: A randomized controlled trial was carried out with 46 depressed inpatients of a psychiatric hospital. Patients were randomly assigned to either a control group that received standard drug and non-drug (cognitive behavioural, occupational, sports, relaxation and music therapy) antidepressive treatment or a remediation group that additionally received 12 sessions of cognitive training for a total of 4 weeks (three sessions per week). An intent to treat analysis and a last observation carried forward method was used for data analyses. RESULTS: Patients of the remediation group demonstrated greater improvements in neurocognitive measures of verbal and nonverbal memory, working memory and executive function (Cohen's d effect sizes between .52 and .98). CONCLUSIONS: These results provide preliminary evidence that cognitive remediation interventions can be successfully applied also in psychiatric inpatients experiencing an acute depressive episode.

Cognitive screening tools in multiple sclerosis revisited: sensitivity and specificity of a short version of Rao's Brief Repeatable Battery.

BACKGROUND: Cognitive deficits are common in multiple sclerosis (MS) and require continuous monitoring. In routine examinations, screening instruments such as the Brief Repeatable Battery (BRB) may serve this purpose. It was suggested that even a shortened version of the BRB, comprising the Symbol Digit Modalities Test (SDMT), Paced Auditory Serial Addition Test (PASAT) and Selective Reminding Test (SRT), may be feasible. However, an evaluation of sensitivity and specificity of the short BRB in comparison to an independent battery of established tests has not yet occurred. Therefore in the current study, this short version of the BRB was matched against the gold standard of an extensive test battery comprehensively assessing neuropsychological functions. METHODS: 127 MS-patients were tested with a short version of the BRB and an extensive procedure. The latter served as the gold standard for defining sensitivity and specificity. RESULTS: For subtests of the short BRB, estimates of sensitivity (38-44 %) and specificity (81-94 %) were obtained. Combining subtests into a single indicator of cognitive deficits yielded increased sensitivity (78 %), while reducing specificity (65 %). CONCLUSION: The short BRB is reasonably sensitive and specific in detecting cognitive deficits. However, these qualities only emerge, if the short BRB is administered as a whole, whereas sensitivity is considerably lower than suggested by previous work, when relying on subtests separately (SDMT, PASAT, SRT). While the short BRB may not be regarded as conclusive as an extensive test battery, it represents a valid and economic screening instrument.

An international road map to improve pain assessment in people with impaired cognition: the development of the Pain Assessment in Impaired Cognition (PAIC) meta-tool.

BACKGROUND: Pain is common in people with dementia, yet identification is challenging. A number of pain assessment tools exist, utilizing observation of pain-related behaviours, vocalizations and facial expressions. Whilst they have been developed robustly, these often lack sufficient evidence of psychometric properties, like reliability, face and construct validity, responsiveness and usability, and are not internationally implemented. The EU-COST initiative "Pain in impaired cognition, especially dementia" aims to combine the expertise of clinicians and researchers to address this important issue by building on previous research in the area, identifying existing pain assessment tools for dementia, and developing consensus for items for a new universal meta-tool for use in research and clinical settings. This paper reports on the initial phase of this collaboration task. METHODS: All existing observational pain behaviour tools were identified and elements categorised using a three-step reduction process. Selection and refinement of items for the draft Pain Assessment in Impaired Cognition (PAIC) meta-tool was achieved through scrutiny of the evidence, consensus of expert opinion, frequency of use and alignment with the American Geriatric Society guidelines. The main aim of this process was to identify key items with potential empirical, rather than theoretical value to take forward for testing. RESULTS: 12 eligible assessment tools were identified, and pain items categorised according to behaviour, facial expression and vocalisation according to the AGS guidelines (Domains 1 - 3). This has been refined to create the PAIC meta-tool for validation and further refinement. A decision was made to create a supporting comprehensive toolkit to support the core assessment tool to provide additional resources for the assessment of overlapping symptoms in dementia, including AGS domains four to six, identification of specific types of pain and assessment of duration and location of pain. CONCLUSIONS: This multidisciplinary, cross-cultural initiative has created a draft meta-tool for capturing pain behaviour to be used across languages and culture, based on the most promising items used in existing tools. The draft PAIC meta-tool will now be taken forward for evaluation according to COSMIN guidelines and the EU-COST protocol in order to exclude invalid items, refine included items and optimise the meta-tool.

Responses to tonic heat pain in the ongoing EEG under conditions of controlled attention.

To confirm the existence of an ongoing electroencephalogram (EEG) pattern that is truly suggestive of pain, tonic heat pain was induced by small heat pulses at 1 °C above the pain threshold and compared to slightly less intense tonic non-painful heat pulses at 1 °C below the pain threshold. Twenty healthy subjects rated the sensation intensity during thermal stimulation. Possible confounding effects of attention were thoroughly controlled for by testing in four conditions: (1) focus of attention directed ipsilateral or (2) contralateral to the side of the stimulation, (3) control without a side preference, and (4) no control of attention at all. EEG was recorded via eight leads according to the 10/20 convention. Absolute power was computed for the frequency bands delta (0.5-4 Hz), theta (4-8 Hz), alpha1 (8-11 Hz), alpha2 (11-14 Hz), beta1 (14-25 Hz), and beta2 (25-35 Hz). Ratings were clearly distinct between the heat and pain conditions and suggestive for heat and pain sensations. Manipulation of attention proved to be successful by producing effects on the ratings and on the EEG activity (with lower ratings and lower EEG activity (theta, beta1, 2) over central areas for side-focused attention). During pain stimulation, lower central alpha1 and alpha2 activity and higher right-parietal and right-occipital delta power were observed compared to heat stimulation. This EEG pattern was not influenced by the manipulation of attention. Since the two types of stimuli (pain, heat) were subjectively felt differently although stimulation intensities were nearby, we conclude that this EEG pattern is clearly suggestive of pain.

Chemo-somatosensory evoked potentials: a sensitive tool to assess conditioned pain modulation?

UNLABELLED: Abstract Background: Chemo-somatosensory evoked potentials (CSSEPs) elicited by chemical stimulation (CO2 gas) of the nasal mucosa have been shown to be sensitive enough to pick up even weak analgesic effects. With the present study we wanted to investigate whether CSSEPs are also a sensitive tool to capture endogenous pain inhibitory mechanisms elicited by conditioned pain modulation (CPM; where a first conditioning stimulus reduces the sensitivity for a second test stimulus) with a conditioning stimulus of rather low noxious load. METHODS: Seventeen healthy participants were tested for CPM effects (conditioning stimulus: tonic heat pain with intensities around the pain threshold induced via a thermode; test stimulus: chemonasal stimulation (73% and 78% CO2)) on CSSEPs and on self-report ratings. RESULTS: We found significant CPM effects in the CSSEPS, with reduced amplitudes and prolonged latencies at several electroencephalogram (EEG) recording positions when using the lower CO2 concentration (73% CO2). In contrast to the visible inhibitory effects on the CSSEPs, subjective ratings of the test stimulus did not reflect CPM action. DISCUSSION: The experimental pain model using CO2 stimuli to elicit CSSEPs proved to be sensitive enough to capture weak CPM effects elicited by a conditioning stimulus of rather low noxious load. The usage of such mild noxious conditioning stimuli-in contrast to stimuli of higher noxious load (e.g., cold pressor test)-has the advantage that the activation of other types of pain inhibitory mechanisms in parallel (like attentional distraction, stress-induced analgesia) can be avoided.

Sex differences in facial expressions of pain: results from a combined sample.

ABSTRACT: Facial expressions of pain play an important role in pain diagnostics and social interactions. Given the prominent impact of sex on various aspects of pain, it is not surprising that sex differences have also been explored regarding facial expressions of pain; however, with inconclusive findings. We aim to further investigate sex differences in facial expressions of pain by using a large, combined sample to maximize statistical power. Data from 7 previous studies of our group were merged, combining in total the data of 392 participants (male: 192, female: 200). All participants received phasic heat pain, with intensities being tailored to the individual pain threshold. Pain intensity ratings were assessed, and facial responses were manually analyzed using the Facial Action Coding. To compare facial and subjective responses between sexes, linear mixed-effects models were used, with study ID as a random effect. We found significant sex differences in facial responses, with females showing elevated facial responses to pain, although they received lower physical heat intensities (women had lower pain thresholds). In contrast, pain intensity ratings did not differ between sexes. Additionally, facial and subjective responses to pain were significantly associated across sexes, with females showing slightly stronger associations. Although variations in facial expressions of pain are very large even within each sex, our findings demonstrate that women facially communicate pain more intensively and with a better match to their subjective experience compared with men. This indicates that women might be better in using facial communication of pain in an intensity-discriminative manner.

Vicarious facilitation of facial responses to pain.

INTRODUCTION: Observing facial expressions of pain has been shown to lead to increased subjective, neural and autonomic pain responses. Surprisingly, these vicarious facilitation effects on its corresponding response channel, namely facial responses to pain have mostly been neglected. We aim to examine whether the prior exposure to facial expressions of pain leads to a facilitation of facial responses to experimental pain; and whether this facilitation is linked to the valence (pain vs. neutral expression) or also linked to specific motor-features of the facial pain expressions (different facial muscle movements). METHOD: Subjective (intensity and unpleasantness ratings) and facial responses (Facial Action Coding System) of 64 participants (34 female) to painful and non-painful heat stimuli were assessed. Before each heat stimulus, video clips of computer-generated facial expressions (three different pain expressions and a neutral expression) were presented. RESULTS: The prior exposure to facial expressions of pain led to increased subjective and facial responses to pain. Further, vicarious pain facilitation of facial responses was significantly correlated with facilitation of unpleasantness ratings. We also found evidence that this vicarious facilitation of facial responses was not only linked to the presentation of pain versus neutral expressions but also to specific motor-features of the pain cue (increase in congruent facial muscle movements). DISCUSSION: Vicarious pain facilitation was found for subjective and facial responses to pain. The results are discussed with reference to the motivational priming hypothesis as well as with reference to motor priming. SIGNIFICANCE: Our study uncovers evidence that facial pain responses are not only influenced by motivational priming (similar to other types of pain responses), but also by motor-priming. These findings shed light on the complexity - ranging from social, affective and motor mechanisms - underling vicarious facilitation of pain.

Is conditioned pain modulation (CPM) affected by negative emotional state?

BACKGROUND: Conditioned pain modulation (CPM) is an experimental paradigm, which describes the inhibition of responses to a noxious or strong-innocuous stimulus, the test stimulus (TS), by the additional application of a second noxious or strong-innocuous stimulus, the conditioning stimulus (CS). As inadequate CPM efficiency has been assumed to be predisposing for clinical pain, the search for moderating factors explaining inter-individual variations in CPM is ongoing. Psychological factors have received credits in this context. However, research concerning associations between CPM and trait factors relating to negative emotions has yielded disappointing results. Yet, the influence of anxious or fearful states on CPM has not attracted much interest despite ample evidence that negative affective states enhance pain. Our study aimed at investigating the effect of fear induction by symbolic threat on CPM. METHODS: Thirty-seven healthy participants completed two experimental blocks: one presenting aversive pictures showing burn wounds (high-threat block) and one presenting neutral pictures (low-threat block). Both blocks contained a CPM paradigm with contact heat as TS and hot water as CS; subjective numerical ratings as well as contact-heat evoked potentials (CHEPs) were assessed. RESULTS: We detected an overall inhibitory CPM effect for CHEPs amplitudes but not for pain ratings. However, we found no evidence for a modulation of CPM by threat despite threat ratings indicating that our manipulation was successful. DISCUSSION: These results suggest that heat/thermal CPM is resistant to this specific type of symbolic threat induction and further research is necessary to examine whether it is resistant to fearful states in general. SIGNIFICANCE: The attempt of modulating heat conditioned pain modulation (CPM) by emotional threat (fear/anxiety state) failed. Thus, heat CPM inhibition again appeared resistant to emotional influences. Pain-related brain potentials proved to be more sensitive for CPM effects than subjective ratings.

Decoding pain from the facial display of patients with dementia: a comparison of professional and nonprofessional observers.

OBJECTIVE: Patients with dementia, whose ability to provide self-report of pain is often impaired, are in crucial need of observers who can detect and judge the patients' pain-indicative behaviors appropriately, in order to initiate treatment. The facial display of pain promises to be especially informative for that purpose. The major aim of the study was to investigate, whether facial pain displays of patients with dementia can be as easily interpreted as facial displays of individuals without cognitive impairment and whether nurses have learned-through their professional training and work experience-to better read the facial display of pain compared with a control group. DESIGN, SUBJECTS AND OUTCOME MEASURES: For that purpose, 21 nurses and 21 age-matched controls watched 120 video clips, showing facial expressions of young and old individuals with and without dementia during slight and moderate noxious stimulation. After each clip, subjects were asked to rate how much pain the observed individual might have experienced. RESULTS: The observer ratings did not differ between nurses and controls as regards pain level and concordance. On the other hand, level and concordance of the pain judgments were strongly influenced by the cognitive status, age, and gender of the observed individuals, with higher and more accurate pain judgments for older and for female individuals. CONCLUSION: Without further contextual information, "professional" observers do not show a superior competence in inferring pain in others by reading their facial display. Therefore, additional training seems needed to reliably prevent that pain goes unnoticed in patients with dementia.