Differential heart rate responses to social and monetary reinforcement in women with obesity

The effects of an acute weight stigma exposure on cardiovascular reactivity among women with obesity and hypertension: A randomized trial

OBJECTIVE

Weight stigma induces cardiovascular health consequences for people with obesity. How stigma affects cardiovascular reactivity in individuals with both obesity and hypertension is not known.

METHODS

In a randomized experiment, we assessed the influence of two video exposures, depicting either weight stigmatizing (STIGMA) or non-stigmatizing (NEUTRAL) scenes, on cardiovascular reactivity [resting blood pressure (BP), heart rate (HR), ambulatory BP (ABP), and ambulatory HR (AHR)], among women with obesity and high BP (HBP; n=24) or normal BP (NBP; n=25). Systolic ABP reactivity was the primary outcome. Laboratory BP and HR were measured before/during/following the videos, and ABP and AHR were measured over 19 hours (10 awake hours, 9 sleep hours) upon leaving the laboratory. A repeated measures ANCOVA tested differences in BP and HR changes from baseline in the laboratory and over ambulatory conditions between the two groups after each video, controlling for body mass index, baseline BP and HR.

RESULTS

Laboratory SBP/DBP increased 5.5+7.3/2.4+8.8mmHg more in women with HBP than NBP following the STIGMA versus NEUTRAL video (Ps<0.05). For the primary outcome, ABP increased more in HBP than NBP over sleep (SBP/DBP=4.2+20.6/4.7+14.2mmHg; Ps<0.05) following the STIGMA versus NEUTRAL video, as did HR during sleep (7.5+15.7bpm more in HBP than NBP; P<0.05).

CONCLUSIONS

Weight stigma increases cardiovascular reactivity among women with obesity and HBP in the laboratory and under ambulatory conditions.

CLINICAL TRIAL REGISTRATION

Registered at ClinicalTrials.gov (Identifier: NCT04161638).

Relationships between experiencing anti-fat microaggressions, body appreciation, and perceived physical and mental health

This study examined whether body appreciation mediates the relationships between anti-fat microaggression experiences and perceived physical and mental health. Using a cross-sectional survey design, our study included 384 adult cisgender women in the United States. We found that anti-fat microaggression experiences had a negative association with body appreciation, and perceived physical and mental health. Body appreciation had a positive relationship to perceived physical and mental health. Our study further suggests that body appreciation is an important modifiable factor that mediates the relationships between anti-fat microaggression experiences and perceived mental and physical health. Implications for practice and research are discussed.

Interactive influences of food, contexts and neurocognitive systems on addictive eating

Compulsive eating is a common symptom of different conditions, including obesity, binge eating disorder and bulimia. One hypothesis is that contemporary food products promote compulsive eating via addiction-like mechanisms. However, what is the addictive substance in food, and what is the phenotypic overlap between obesity / eating disorders and addictions are questions that remain unresolved. In this review, we applied a multilevel framework of addiction, which encompasses the 'drug' (certain foods), the person's mindset, and the context, to improve understanding of compulsive eating. Specifically, we reviewed evidence on the addictive properties of specific foods, the neurocognitive systems that control dietary choices, and their interaction with physical, emotional and social contexts. We focused on different target groups to illustrate distinct aspects of the proposed framework: the impact of food and contextual factors were examined across a continuum, with most studies conducted on healthy participants and subclinical populations, whereas the review of neurocognitive aspects focused on clinical groups in which the alterations linked to addictive and compulsive eating are particularly visible. The reviewed evidence suggest that macronutrient composition and level of processing are associated with the addictive properties of food; there are overlapping neuroadaptations in reward and decision-making circuits across compulsive eating conditions; and there are physical and social contexts that fuel compulsive eating by exploiting reward mechanisms and their interaction with emotions. We conclude that a biopsychosocial model that integrates food, neurobiology and context can provide a better understanding of compulsive eating manifestations in a transdiagnostic framework.

Internalized weight bias and cortisol reactivity to social stress

Weight-associated stigmatization and discrimination may induce chronic stress in individuals with obesity. As a consequence, this stressor may cause an imbalance of HPA stress axis leading to increased eating behavior, and ultimately, weight gain. However, the direct link between internalized weight bias and stress response to acute stressors via cortisol secretion has not been investigated so far. Therefore, the purpose of this study was to investigate the interaction between internalized weight stigma as a stressor and cortisol reactivity in an acute psychosocial stress situation induced by the Trier Socials Stress Test for groups (TSST-G). Participants with BMI >30 kg/m² (n = 79) were included in the study. Results reveal that while individuals with low internalized stigma reacted as predicted with an increase in cortisol secretion to acute psychosocial stress, individuals with medium or high internalized stigma did not show a typical cortisol response. However, these findings depend on the several factors, for instance on gender. In sum, acute stress in individuals with internalized weight bias seems to blunt HPA axis reactions to acute psychosocial stress. The study contributes to the understanding of the psychological and endocrinological consequences of internalized weight bias and underlines the importance of interventions to reduce stigmatization.

Development of a Classical Conditioning Task for Humans Examining Phasic Heart Rate Responses to Signaled Appetitive Stimuli: A Pilot Study

Cardiac responses to appetitive stimuli have been studied as indices of motivational states and attentional processes, the former being associated with cardiac acceleration and latter deceleration. Very few studies have examined heart rate changes in appetitive classical conditioning in humans. The current study describes the development and pilot testing of a classical conditioning task to assess cardiac responses to appetitive stimuli and cues that reliably precede them. Data from 18 adults were examined. They were shown initially neutral visual stimuli (putative CS) on a computer screen followed by pictures of high-caloric food (US). Phasic cardiac deceleration to food images was observed, consistent with an orienting response to motivationally significant stimuli. Similar responses were observed to non-appetitive stimuli when they were preceded by the cue associated with the food images, suggesting that attentional processes were engaged by conditioned stimuli. These autonomic changes provide significant information about classical conditioning effects in humans.

Learning something new versus changing your ways: Distinct effects on midfrontal oscillations and cardiac activity for learning and flexible adjustments

We need to be able to learn new behaviour, but also be capable of changing existing routines, when they start conflicting with our long-term goals. Little is known about to what extent blank-slate learning of new and adjustment of existing behavioural routines rely on different neural and bodily mechanisms. In the current study, participants first acquired novel stimulus-response contingencies, which were subsequently randomly changed to create the need for flexible adjustments. We measured midfrontal theta oscillations via EEG as an indicator of neural conflict processing, as well as heart rate as a proxy of autonomic activity. Participants' trial-wise learning progress was estimated via computation modelling. Theta power and heart rate significantly differed between correct and incorrect trials. Differences between correct and incorrect trials in both neural and cardiac feedback processing were more pronounced for adjustments compared to blank-slate learning. This indicates that both midfrontal and cardiac processing are sensitive to changes in stimulus-response contingencies. Increases in individual learning rates predicted lower impact of performance feedback on midfrontal theta power, but higher impact on heart rate. This suggests that cardiac and midfrontal reactivity are partially reflective of different mechanisms related to feedback learning. Our results shed new light on the role of neural and autonomic mechanisms for learning and behavioural adjustments.

Links between discrimination and cardiovascular health among socially stigmatized groups: A systematic review

BACKGROUND

There is a high prevalence of cardiovascular disease across diverse groups in the U.S. population, and increasing research has identified stigma as a potential barrier to cardiovascular disease prevention and treatment. This systematic review examines evidence linking discrimination and cardiovascular health among socially stigmatized groups.

STUDY DESIGN

Six databases were systematically reviewed from inception through February 2018 for studies with adult subjects, focusing on cardiovascular health indicators among social groups stigmatized because of their gender, race/ethnicity, age, body weight/obesity, or sexual orientation. The Newcastle-Ottawa Scale was used to evaluate the methodological quality and risk of bias for nonrandomized studies, and the Cochrane Collaboration 7-item domain for randomized controlled and experimental trials.

RESULTS

The search identified 84 eligible studies published between 1984 and 2017. Studies retrieved were categorized according to demonstrated links between stigma and cardiovascular disease risk factors including blood pressure (n = 45), heart rate variability (n = 6), blood/saliva cardiovascular biomarkers (n = 18), as well as other indicators of cardiovascular health (n = 15). Based on the findings from included studies, 86% concluded that there was a significant relationship among stigma or discrimination and cardiovascular health indicators among socially stigmatized groups. However, there were varying degrees of evidence supporting these relationships, depending on the type of discrimination and cardiovascular health indicator. The current evidence implies an association between perceived discrimination and cardiovascular health. However, a majority of these studies are cross-sectional (73%) and focus on racial discrimination (79%), while using a wide variety of measurements to assess social discrimination and cardiovascular health.

CONCLUSIONS

Future research should include longitudinal and randomized controlled trial designs, with larger and more diverse samples of individuals with stigmatized identities, using consistent measurement approaches to assess social discrimination and its relationship with cardiovascular health.

Cardiac Concomitants of Feedback and Prediction Error Processing in Reinforcement Learning

Successful learning hinges on the evaluation of positive and negative feedback. We assessed differential learning from reward and punishment in a monetary reinforcement learning paradigm, together with cardiac concomitants of positive and negative feedback processing. On the behavioral level, learning from reward resulted in more advantageous behavior than learning from punishment, suggesting a differential impact of reward and punishment on successful feedback-based learning. On the autonomic level, learning and feedback processing were closely mirrored by phasic cardiac responses on a trial-by-trial basis: (1) Negative feedback was accompanied by faster and prolonged heart rate deceleration compared to positive feedback. (2) Cardiac responses shifted from feedback presentation at the beginning of learning to stimulus presentation later on. (3) Most importantly, the strength of phasic cardiac responses to the presentation of feedback correlated with the strength of prediction error signals that alert the learner to the necessity for behavioral adaptation. Considering participants' weight status and gender revealed obesity-related deficits in learning to avoid negative consequences and less consistent behavioral adaptation in women compared to men. In sum, our results provide strong new evidence for the notion that during learning phasic cardiac responses reflect an internal value and feedback monitoring system that is sensitive to the violation of performance-based expectations. Moreover, inter-individual differences in weight status and gender may affect both behavioral and autonomic responses in reinforcement-based learning.

Parasympathetic cardio-regulation during social interactions in individuals with obesity-The influence of negative body image

Individuals with obesity in Western societies often face weight-related stigmatization and social exclusion. Recurrent exposure to prejudice and negative social feedback alters one's behavior in future social interactions. In this study, we aimed to investigate autonomic nervous system and affective responses to social interactions in individuals with obesity. Women and men with (n = 56) and without (n = 56) obesity participated in episodes of social inclusion and social exclusion using a virtual ball-tossing game. During the experiment, heart rate was measured and parasympathetic activity (overall high-frequency power and event-related cardiac slowing) was analyzed. Our results show that in novel social interactions, women with obesity, relative to the other groups, exhibited the strongest increase in parasympathetic activity. Furthermore, parasympathetic activity was related to a more negative body image in individuals with obesity, but not in lean individuals. Additionally, women with obesity reported a stronger decrease in mood after social exclusion than did the other participants. Our results demonstrate influences of objective and subjective bodily characteristics on parasympathetic cardio-regulation during social interactions. In particular, they show behavioral and physiological alterations during social interactions in women with obesity.