Placebo Hypoalgesia and Nocebo Hyperalgesia Induced by Observational Learning May Be Difficult to Disentangle in a Laboratory Setting.

Observational learning (OBL) (seeing pain/pain treatment in others) can evoke placebo hypoalgesia and nocebo hyperalgesia. Data that compare these effects and illuminates the role of expectations and empathy are scarce. Healthy participants (n = 105) were randomized to: 1) placebo OBL, 2) nocebo OBL, or 3) no-observation control group. OBL consisted of a model simulating pain relief or increase after a sham ointment was applied to one arm. Pain was evoked with thermal stimuli on both arms (ointment, contralateral) at baseline and postobservation. Expectations, pain ratings, and physiological data (eg, skin conductance level) were collected. A 3 × 2 × 2 (Group × Arm × Phase) mixed analyses of variance revealed a 3-way interaction that confirmed that OBL modulates pain: F(2, 93) = 6.08, P = .003, ηp2 = .12. Significant baseline-to-post-observation pain increases were shown in the nocebo OBL group, with a bigger increase for the arm with ointment (both P ≤ .007). In the placebo OBL group, pain was higher for the contralateral relative to the ointment arm (P < .001). Baseline-to-post-observation pain increase was significant for the contralateral arm (P < .001). Expectation mediated these effects. Skin conductance level decreased over time during ointment trials in the nocebo OBL group, suggesting reduced physiological arousal. The findings illustrate that OBL modulates pain through expectations. In the placebo OBL group, the pain did not decrease for the ointment but increased for the contralateral stimuli, which may reflect nocebo learning. Experimental OBL paradigms typically examine relative differences between ointment and contralateral cues. This can complicate disentangling placebo hypoalgesia and nocebo hyperalgesia in laboratory settings. Implications for existing theories are discussed. PERSPECTIVE: Data that systematically compare placebo hypoalgesia and nocebo hyperalgesia induced by OBL are scarce. The current work illustrates that these effects may be more difficult to disentangle than previously assumed, which could have implications for existing theories on OBL and placebo effects and their translation to clinical practice.

Pain Rating is Worth a Thousand Words: Nocebo Hyperalgesia Induced by Verbal Modeling Prevails Over the Effects of Symbolic Modeling and Verbal Suggestion.

This study compares the effectiveness of verbal modeling, symbolic modeling, and verbal suggestion in inducing nocebo hyperalgesia. It is the first study to examine the contribution of stress to observationally induced nocebo hyperalgesia. This study's experimental groups represented various sources of social information: a group of people participating in the study (verbal modeling), a single participant (symbolic modeling), and an experimenter (verbal suggestion). During the experiment, participants received electrocutaneous stimuli at the same intensity, some of which were applied with a nocebo (sham device). Participants in the verbal modeling group were acquainted with pain ratings that had allegedly been provided by other participants. The ratings suggested that other participants experienced more pain in the nocebo trials than in the control trials. In the symbolic modeling group, participants observed a videotaped model experiencing more pain in the nocebo than in the control trials. In the verbal suggestion group, participants received a verbal suggestion of hyperalgesia in the nocebo trials and no suggestion in the control trials. No manipulations were used in the control group. To investigate whether nocebo hyperalgesia is stable over time, an additional extinction phase was conducted. Nocebo hyperalgesia was induced by verbal modeling only and was partially mediated by expectancy. Stress was a significant moderator of the induced effect. Nocebo hyperalgesia was extinguished during the extinction phase. The obtained results provide potential implications for minimizing nocebo hyperalgesia in clinical practice by, for instance, controlling patients' expectancies and stress levels. PERSPECTIVE: The study shows the role of pain-related information derived from other people in shaping negative treatment experiences in the individual. Because information from others has a particular impact on individuals experiencing stress, both this information and the stress level of patients should be monitored in the treatment process.

Associations of self-perceived and objective BMI and adiposity status among adolescents from Kraków (Poland).

OBJECTIVES: The study aimed to determine the association of self-perceived and objective BMI and adiposity status among adolescents from Kraków (Poland). METHODS: The study was carried out in 2022, in randomly selected schools in Kraków (Poland). The study group consisted of 93 individuals (47 girls and 46 boys) aged 11-15. Anthropometric characteristics included body height, body weight and body fat percentage (%BF), measured by bioimpedance method (BIA). Body Mass Index (BMI) was calculated. Self-perceived body weight/adiposity status was obtained using a question extracted from the Polish version of the Health Behavior in School-Aged Children (HBSC). RESULTS: The results of the current study provide evidence that girls who were dissatisfied with their bodies thought they were too fat, while boys, on the contrary, thought they were too thin. Trends in this regard begin to appear in girls around the age of 11, while in boys at around 12/13. CONCLUSION: It is worth noting that the dissatisfaction of the examined children with their physique coincided with the onset of puberty. As some children begin puberty earlier than others, making them stand out from their peers. They begin to give more attention to their bodies and compare them with the physiques of others. Additionally, comparing one's body to the "ideal figure" depicted on social media and ones inability to obtain it also can lead to body dissatisfaction.

Intergenerational Changes in the Waist Circumference and Selected Associated Indicators among Children and Adolescents from Kraków (Poland), between 1983 and 2020.

The aim of the study was to examine the direction of the secular changes in the waist and hips circumferences, as well as selected associated body proportions, among children and adolescents from Kraków, Poland. The study group included 8-18-year-olds examined in three cross-sectional studies (1983, 2010, and 2020). The analyzed characteristics included body height, circumferences of the waist and hips, which were used to calculate Waist-to-Hip Ratio (WHR), and Waist-to-Height Ratio (WHtR). There was a secular increase regarding the majority of the analyzed features, particularly for the younger children (i.e., prepubertal/early pubertal age). The trends were also especially evident when comparing the results of the 1983 series to the results of their peers examined in 2020. An opposite trend was noted in adolescent girls. The observed changes reflect the secular trend resulting from changes in body composition and fat distribution happening due to alterations in the lifestyle and socio-economic environment of the population over the years. It should also be stressed that the increase in the studied characteristics occurred mainly in younger children. This suggests that the observed changes may have resulted from a shift in the age of maturation and also from the personal and social motivators characteristic for late adolescence.

Changes in the adiposity level and prevalence of overweight/obesity among children from Kraków (Poland) within the last decade (from 2010 to 2020).

The aim of this study was to assess the changes in the prevalence of overweight, obesity and high adiposity in children and adolescents from Krakow (Poland), between the years 2010 and 2020. Two cross-sectional series of anthropometric measurements were carried out in 2010 and 2020. Analysed characteristics included: body height and weight, BMI (Body Mass Index), body adiposity (%BF). The subjects were categorised according to their BMI (underweight, normal weight, overweight, obesity), as well as %BF (low, normal, high body fat).The research was conducted in randomly selected primary schools in Krakow (Poland). Studied cohorts (8-15 years of age), which represented four of the traditional residential districts: Sródmiescie, Podgórze, Krowodrza and Nowa Huta. Among the girls, there was a negative secular trend regarding the prevalence of underweight and obesity. On the other hand, there also was a positive trend concerning the prevalence of overweight and low and high body fat. In boys, there was a negative secular trend regarding the prevalence of underweight and low adiposity. There was also a generally positive secular trend regarding the prevalence of overweight, obesity as well as high adiposity in boys. The findings of this study are particularly significant because detailed knowledge of the prevalence of overweight/obesity in childhood and adolescence is crucial for the future health of entire populations. Further studies should also take into account the levels of physical fitness and activity of the examined population.