Nocebo Hyperalgesia can be Induced by the Observation of a Model Showing Natural Pain Expressions.

OBJECTIVES: Nocebo hyperalgesia is an increase in pain through the expectation of such an increase as a consequence of a sham treatment. Nocebo hyperalgesia can be induced by observation of a model demonstrating increased pain via verbal pain ratings. The aim of the present study was to investigate whether observing natural pain behavior, such as facial pain expressions, can also induce nocebo responses. MATERIALS AND METHODS: Eighty female participants (age: 22.4 y±4.8) underwent a pressure-pain procedure (algometer) on both hands and rated their pain on a numerical rating scale. All participants received ointment on one of their hands, but no explanation was given for this. Before their own participation, the participants watched a video in which a woman underwent the same procedure and who either modeled increased pressure pain upon ointment application (nocebo condition) or showed a neutral facial expression throughout (control condition). RESULTS: A 2×2 analysis of variance with condition (nocebo; control) as a between-subjects factor and ointment application (with; without) as a within-subject factor revealed a main effect for ointment and a condition×ointment interaction. In the nocebo condition, pain ratings were higher with ointment than without. DISCUSSION: For the first time, it was shown that watching a model demonstrating pain through facial expressions induced nocebo hyperalgesia. As we mostly express pain through natural pain behavior rather than through pain ratings, this paradigm extends our knowledge of observational learning about pain and may have implications for contexts in which persons watch others undergo painful procedures.

Long-Term Outcomes of a Multimodal Day-Clinic Treatment for Chronic Pain under the Conditions of Routine Care.

Chronic pain has high prevalence rates and is one of the top causes of years lived with disability. The aim of the present study was to evaluate the long-term effects of a multimodal day-clinic treatment for chronic pain. The sample included 183 chronic pain patients (114 females and 69 males; 53.3 ± 9.8 years) who participated in a four-week multimodal day-clinic treatment for chronic pain. The patients' average current pain intensity (NRS), sensory and affective pain (Pain Perception Scale), and depression and anxiety (HADS) were assessed at pre- and posttreatment, as well as at three follow-ups (one month, six months, and twelve months after completion of the treatment). Multilevel models for discontinuous change were performed to evaluate the change of the outcome variables. Improvements from pretreatment to posttreatment and from pretreatment to all follow-ups emerged for pain intensity (NRS; 0.54 ≤ d ≤ 0.74), affective pain (Pain Perception Scale; 0.24 ≤ d ≤ 0.47), depression (HADS; 0.38 ≤ d ≤ 0.53), and anxiety (HADS; 0.26 ≤ d ≤ 0.43) (all p < 0.05). Sensory pain as assessed with the Pain Perception Scale did not show any significant change. Patients suffering from chronic pain benefited from the multimodal pain treatment up to twelve months after completion of the treatment.

Nocebo hyperalgesia: contributions of social observation and body-related cognitive styles.

PURPOSE: Recently, it has been shown that nocebo hyperalgesia can be acquired through observational learning. The aim of this study was to investigate socially induced nocebo hyperalgesia and its relationship with pain catastrophizing, somatic complaints, hypochondriacal concerns, and empathy. PARTICIPANTS AND METHODS: Ninety-seven women (43.1±15.5 years) were randomly assigned to one of the two conditions. Participants in the nocebo condition (NC) watched a video in which a female model displayed more pain when an ointment was applied and less pain when no ointment was applied. In the control condition (CC), the model demonstrated low pain with and without the ointment. Subsequently, all participants received three pressure pain stimuli (60 seconds) on each hand. On one hand, the ointment was applied prior to the stimulation. The order of the stimulation of the fingers (middle, index, or ring finger), the side of ointment application (left or right hand), and the side with which the stimulation began were randomized within each group and balanced across the groups. Depending on the randomization, the pressure pain application started with or without ointment and on the left or right hand. Pain ratings on a numerical rating scale (0-10) were collected. In addition, the participants completed questionnaires regarding body-related cognitive styles and empathy. RESULTS: There was a significant difference in the pain ratings between the CC and the NC. The effect of ointment application was also significant, but no interaction between condition and ointment application was found. Only in the CC did the nocebo response correlate with hypochondriacal concerns and somatic complaints. CONCLUSION: Application of an ointment as well as the observation of a model demonstrating more pain after a treatment produced elevated pain ratings. Cognitive styles were not related to the socially induced nocebo response, but were related to the nocebo response in the CC.

Nocebo hyperalgesia induced by social observational learning.

Nocebo effects can be acquired by verbal suggestion, but it is unknown whether they can be induced through observational learning and whether they are influenced by factors known to influence pain perception, such as pain anxiety or pain catastrophizing. Eighty-five female students (aged 22.5 ± 4.4 years) were randomly assigned to one of three conditions. Participants in the control condition (CC) received information that an ointment had no effect on pain perception. Participants in the verbal suggestion condition (VSC) received information that it increased pain sensitivity. Participants in the social observational learning condition (OLC) watched a video in which a model displayed more pain when ointment was applied. Subsequently, all participants received three pressure pain stimuli (60 seconds) on each hand. On one hand, the ointment was applied prior to the stimulation. Numerical pain ratings were collected at 20-second intervals during pain stimulation. The participants filled in questionnaires regarding pain-related attitudes (Pain Anxiety Symptoms Scale, Pain Catastrophizing Scale, and Somatosensory Amplification Scale). Participants in the OLC showed higher pain ratings with than without ointment. Pain ratings within the CC and the VSC were at the same level with and without ointment. In the VSC, the pain ratings were higher than in the CC with and without ointment. The nocebo response correlated with pain catastrophizing but not with pain anxiety or somatosensory amplification. A nocebo response to pressure pain was induced by observational learning but not by verbal suggestion. This finding highlights the importance of investigating the influence of observational learning on nocebo hyperalgesia.