Department of Clinical Neuroscience, Psychology Division, Karolinska Institutet, Stockholm, Sweden; Stress Research Institute, Stockholm University, Stockholm, Sweden; Institute of Medical Psychology and Behavioral Immunobiology, University Hospital Essen, Essen, Germany.
Department of Clinical Neuroscience, Neuro Division, Karolinska Institutet, Stockholm, Sweden; Osher Center for Integrative Medicine, Karolinska Institutet, Stockholm, Sweden.
Brain Behav Immun. 2018 Nov;74:213-221. doi: 10.1016/j.bbi.2018.09.008. Epub 2018 Sep 11.
People react very differently when sick, and there are only poor correlations between the intensity of the immune response and sickness behavior. Yet, alternative predictors of the individual differences in sickness are under-investigated. Based on the predictive coding model of placebo responses, where health outcomes are function of bottom-up sensory information and top-down expectancies, we hypothesized that individual differences in behavioral changes during sickness could be explained by individual top-down expectancies and prediction errors.
Twenty-two healthy participants were made sick by intravenously administering lipopolysaccharide (2 ng/kg body weight). Their expectations of becoming sick were assessed before the injection.
Participants having lower expectations of becoming sick before the injection reacted with more emotional distress (i.e., more negative affect and lower emotional arousal) than those with high expectations of becoming sick, despite having similar overall sickness behavior (i.e., a combined factor including fatigue, pain, nausea and social withdrawal). In keeping with a predictive coding model, the "prediction error signal", i.e., the discrepancy between the immune signal and sickness expectancy, predicted emotional distress (reduction in emotional arousal in particular).
The current findings suggest that the emotional component of sickness behavior is, at least partly, shaped by top-down expectations. Helping patients having a realistic expectation of symptoms during treatment of an illness may thus reduce aggravated emotional responses, and ultimately improve patients' quality of life and treatment compliance. REGISTRATION: "Endotoxin-induced Inflammatory and Behavioral Responses and Predictors of Individual Differences", https://clinicaltrials.gov/ct2/show/NCT02529592, registration number: NCT02529592.
人们在生病时的反应差异很大，免疫反应的强度与疾病行为之间只有很差的相关性。然而，个体疾病差异的其他预测因素研究不足。基于安慰剂反应的预测编码模型，健康结果是由自上而下的期望和自下而上的感觉信息共同作用的，我们假设疾病期间个体行为变化的个体差异可以用个体自上而下的期望和预测误差来解释。
22 名健康参与者通过静脉内注射脂多糖（2ng/kg 体重）来患病。在注射前评估他们对患病的期望。
与那些对患病有高期望的参与者相比，注射前对患病期望较低的参与者表现出更多的情绪困扰（即更负面的情绪和更低的情绪唤醒），尽管他们的整体疾病行为相似（即包括疲劳、疼痛、恶心和社交退缩的综合因素）。与预测编码模型一致，“预测误差信号”，即免疫信号与疾病期望之间的差异，预测了情绪困扰（特别是情绪唤醒的降低）。
目前的研究结果表明，疾病行为的情绪成分至少部分是由自上而下的期望塑造的。因此，在治疗疾病期间帮助患者对症状有一个现实的预期，可能会减轻加重的情绪反应，并最终提高患者的生活质量和治疗依从性。
“内毒素诱导的炎症和行为反应及个体差异的预测因素”，https://clinicaltrials.gov/ct2/show/NCT02529592，注册号：NCT02529592。
