Neural Correlates of Food Cue Exposure Intervention for Obesity: A Case-Series Approach.

BACKGROUND: People with overweight have stronger reactivity (e.g., subjective craving) to food cues than lean people, and this reactivity is positively associated with food intake. Cue reactivity is a learned response that can be reduced with food cue exposure therapy. OBJECTIVES: It was hypothesized that participants after food cue exposure therapy would show reduced neural activity in brain regions related to food cue reactivity and increased neural activity in brain regions related to inhibitory-control as compared to participants receiving a control lifestyle intervention. METHOD: Neural activity of 10 women with overweight (BMI ≥ 27 kg/m2) in response to individually tailored visually presented palatable high-caloric food stimuli was examined before vs. after a cue exposure intervention (n = 5) or a control lifestyle (n = 5) intervention. Data were analyzed case-by-case. RESULTS: Neural responses to food stimuli were reduced in food-cue-reactivity-related brain regions after the lifestyle intervention in most participants, and generally not after the cue exposure therapy. Moreover, cue exposure did not lead to increased activity in inhibitory-control-related brain regions. However, decreased neural activity after cue exposure was found in most participants in the lateral occipital complex (LOC), which suggests a decreased visual salience of high-caloric food stimuli. CONCLUSION: Receiving a cue exposure therapy did not lead to expected neural responses. As cue exposure relies on inhibitory learning mechanisms, differences in contexts (e.g., environments and food types) between the intervention setting and the scanning sessions may explain the general lack of effect of cue-exposure on neural activity.

Tackling sabotaging cognitive processes to reduce overeating; expectancy violation during food cue exposure.

Calorie-reduced diets to combat obesity do work, but they only work when one sticks to the diet and the - relatively small - weight loss usually is short-lived. It is argued that calorie-reduced diets should converge with enduring lifestyle changes: the diet is just the start of a lifelong new eating pattern. Getting people to change their lifestyles forever could increase the amount of lost weight and prevent relapse. However, a real behavior change is difficult, especially when longstanding habits are involved and the change is intended for the rest of life. It is argued here that adherence to a new lifestyle is much easier if sabotaging cognitive processes are tackled. An overview is given of four studies into the effects of exposure to reduce appetitive responding to tempting food cues. A robust effect of exposure on the ad lib intake of exposed foods was found in all studies: participants ate significantly less of exposed foods after exposure compared to control interventions but no generalization to non-exposed foods was found. The reduced food intake after exposure was associated with a violation of overeating expectancies. It is discussed that lifestyle interventions might benefit from techniques that are really able to change longstanding habits. Specifically, the violation of overeating expectancies during exposure seems to be critical for controlled eating and should therefore be part of lifestyle interventions for obesity.

Individual differences in extinction learning predict weight loss after treatment: A pilot study.

Learning theorists suggest extinction learning to be a central mechanism in weight loss success; however, empirical studies are scarce. In this pilot study, it was examined whether individual differences in extinction learning predict outcome after weight loss treatment. Overweight and obese individuals first completed a laboratory conditioning task in which individual differences in extinction learning were assessed. Next, they were randomised to one of two weight loss interventions: cue exposure therapy (CET), which is considered the clinical analogue of laboratory extinction, or a control lifestyle intervention. In line with expectations, better extinction learning in the laboratory task was associated with more weight loss at both post-treatment (CET only) and follow-up (both interventions) measurements. In contrast, two other indices of treatment success (reduction in overeating expectancies and ad libitum food intake during a laboratory taste test) showed no associations with pre-treatment extinction learning. It is suggested that extinction learning may be a core mechanism underlying weight loss success, and hence, an important target for new obesity interventions.

Exposure therapy vs lifestyle intervention to reduce food cue reactivity and binge eating in obesity: A pilot study.

BACKGROUND AND OBJECTIVES: Learning models of overeating predict that exposure therapy is effective in reducing food cue reactivity and overeating. This pilot study tested an eight-session exposure therapy aimed at inhibitory learning vs. an active control condition aimed at lifestyle improvement for obesity (treatment-as-usual). Main outcomes are snacking behavior, eating psychopathology, food cue reactivity, and weight loss. Change in overeating expectancies was assessed as mediator for outcomes, and the associations between habituation of eating desires and outcomes were investigated in the exposure condition. Sleep quality was investigated as moderator for outcomes. METHODS: 45 overweight women were randomly assigned to the exposure intervention or control condition. The main outcomes, overeating expectancies and sleep quality were re-assessed at post-treatment and three-month follow-up. Habituation of eating desires was measured during exposure sessions. RESULTS: Compared to the control intervention, exposure led to a significantly stronger reduction in snacking behavior of exposed foods, though this effect did not generalize to non-exposed foods, and stronger binge eating frequency. The exposure condition lost significantly more weight at post-treatment and follow-up than the lifestyle condition. Changes of expectancies mediated the effect of condition on kcal consumption of exposed foods, while habituation during exposure was not related to better treatment outcome. Sleep quality did not moderate the effect of condition on treatment outcome. LIMITATIONS: Small sample size and limited follow-up period. CONCLUSIONS: This short exposure therapy reduced snacking behavior, binge eating and weight more than a lifestyle intervention and is therefore a recommendable intervention for obesity and overeating disorders.

Acquisition and generalization of appetitive responding in obese and healthy weight females.

Findings of a few recent studies suggest that obesity is characterized by deficits in appetitive learning about food cues. This could point towards an increased tendency in obese individuals to overgeneralize appetitive responding to stimuli that resemble the conditioned food cue - possibly explaining frequent eating desires and overeating in obesity. The current study aimed to investigate whether obese individuals 1) indeed exhibit appetitive learning deficits and 2) show overgeneralization of conditioned appetitive responses. Obese and matched healthy-weight females (N = 85) completed a differential appetitive conditioning task using food as rewards. First, appetitive responding to a novel stimulus was learned (acquisition phase), after which stimuli with varying resemblance to the food-associated stimulus were presented (generalization phase). Cue-elicited eating expectancies, eating desires, stimulus evaluations, and actual food intake were examined. Results indicated successful acquisition of appetitive responding across all outcome measures. The acquired responses also generalized, indicating that generalization can function as an additional mechanism by which learned food cues can promote food consumption. The data further suggested that overweight and obesity are not characterized by appetitive learning deficits nor by overgeneralization, but that a subgroup of obese individuals (those high in trait anxiety) may be more prone to overgeneralization of appetitive responding.

Learned Overeating: Applying Principles of Pavlovian Conditioning to Explain and Treat Overeating.

PURPOSE OF REVIEW: This review provides an overview of recent findings relating to the role of Pavlovian conditioning in food cue reactivity, including its application to overeating and weight loss interventions. RECENT FINDINGS: Both in the laboratory and in real life, cue-elicited appetitive reactivity (e.g., eating desires) can be easily learned, but (long-term) extinction is more difficult. New findings suggest impaired appetitive learning in obesity, which might be causally related to overeating. The clinical analogue of extinction-cue exposure therapy-effectively reduces cue-elicited cravings and overeating. While its working mechanisms are still unclear, some studies suggest that reducing overeating expectancies is important. SUMMARY: Pavlovian learning theory provides a still undervalued theoretical framework of how cravings and overeating can be learned and how they might be effectively tackled. Future studies should aim to elucidate inter-individual differences in Pavlovian conditioning, study ways to strengthen (long-term) extinction, and investigate the working mechanisms of cue exposure therapy.

Cue exposure therapy reduces overeating of exposed and non-exposed foods in obese adolescents.

BACKGROUND AND OBJECTIVES: This study tested whether two sessions of food cue exposure therapy reduced eating in the absence of hunger (EAH), specified for exposed and non-exposed food, in overweight and obese adolescents, and whether habituation of food cue reactivity and reduced CS-US expectancies predicted a decrease in EAH. METHODS: 41 overweight adolescents (aged 12-18 years) were randomly assigned to a cue exposure intervention or a lifestyle intervention (control condition). Habituation of food cue reactivity (self-reported desire to eat and salivation) and CS-US expectancy were measured during both sessions, and EAH was measured at the end of session two. RESULTS: Compared to the control condition, the cue exposure condition showed less EAH for the exposed food item as well as for the non-exposed food items. Larger within-session (WSH) and between-session habituation (BSH) of cue reactivity were not related to less EAH, change in CS-US expectancy was unrelated to EAH. LIMITATIONS: The study was underpowered, and compliance to homework instructions between sessions was poor, intervention effects might have been larger when participants adhered to daily homework exercises. CONCLUSIONS: Food cue exposure was effective to reduce EAH of exposed and non-exposed food items, indicating generalisability of the exposure effect. In line with exposure effects in anxiety disorders, habituation was not found to benefit outcome, though the present data do also not provide evidence that CS-US expectancy violation predicts EAH.

What works better? Food cue exposure aiming at the habituation of eating desires or food cue exposure aiming at the violation of overeating expectancies?

OBJECTIVE: This study tested the role of habituation of eating desires and violation of overeating expectancies during food cue exposure in obese women. METHOD: 52 obese females were randomised into a two-session exposure condition aimed at habituation, a two-session exposure condition aimed at expectancy violation, or a no-treatment control condition. Eating in the absence of hunger of foods included during cue exposure (i.e., exposed foods) and foods not included during cue exposure (i.e., non-exposed foods), and duration of exposure were measured. RESULTS: Both cue exposure conditions ate significantly less of the exposed foods compared to the control condition, though there were no differences between both types of exposure. No differences were found between conditions regarding the eating of non-exposed foods. In addition, the duration of exposure was not different between both cue exposure conditions. CONCLUSIONS: While food cue exposure in obese women led to less eating of exposed foods, focusing on either habituation of eating desires or expectancy violation did not matter. It is discussed why exposure works.

Altered appetitive conditioning in overweight and obese women.

Overweight and obese individuals show increased psychological and physiological reactivity to food cues and many of them have difficulties in achieving long-term weight loss. The current study tests whether abnormalities in the learning and extinction of appetitive responses to food cues might be responsible for this. Overweight/obese and healthy weight women completed a differential appetitive conditioning task using food as rewards, while eating expectancies, eating desires, conditioned stimulus evaluations, salivation, and electrodermal responses were assessed during an acquisition and extinction phase. Results suggested reduced discriminative conditioning in the overweight/obese group, as reflected by a worse acquisition of differential eating desires and no successful acquisition of differential evaluative responses. Some evidence was also found for impaired contingency learning in overweight and obese individuals. No group differences in conditioned salivation and skin conductance responses were found and no compelling evidence for differences in extinction was found as well. In sum, the current findings indicate that overweight and obesity may be characterized by reduced appetitive conditioning. It is suggested that this could be causally related to overeating via stronger context conditioning or a tendency towards overgeneralization in overweight and obese individuals.

Enhancing inhibitory learning to reduce overeating: Design and rationale of a cue exposure therapy trial in overweight and obese women.

The prevalence of overweight and obesity has increased substantially over the last decades. Weight loss attempts in overweight individuals are common, though they seldom result in successful long-term weight loss. One very promising treatment is food cue exposure therapy, during which overweight individuals are repeatedly exposed to food-associated cues (e.g., the sight, smell and taste of high-calorie foods, overeating environments) without eating in order to extinguish cue-elicited appetitive responses to food cues. However, only few studies have tested the effectiveness of cue exposure, especially with regards to weight loss. For exposure treatment of anxiety disorders, it has been proposed that inhibitory learning is critical for exposure to be effective. In this RCT, we translated techniques proposed by Craske et al. (2014) to the appetitive domain and developed a novel cue exposure therapy for overeating aimed at maximizing inhibitory learning. The current RCT tested the effectiveness of this 8-session cue exposure intervention relative to a control intervention in 45 overweight adult (aged 18-60) females at post-treatment and 3-month follow-up, of which 39 participants completed the study. Weight loss, eating psychopathology, food cue reactivity, and snacking behaviour were studied as main treatment outcomes, and mediators and moderators of treatment effects were studied. The presented study design represents an innovative effort to provide valuable clinical recommendations for the treatment of overeating and obesity.

From lab to clinic: Extinction of cued cravings to reduce overeating.

Food cue reactivity is a strong motivation to eat, even in the absence of hunger. Therefore, food cue reactivity might sabotage healthy eating, induce weight gain and impede weight loss or weight maintenance. Food cue reactivity can be learned via Pavlovian appetitive conditioning: It is easily acquired but the extinction of appetitive responding seems to be more challenging. Several properties of extinction make it fragile: extinction does not erase the original learning and extinction is context-dependent. These properties threaten full extinction and increase the risk of full relapse. Extinction procedures are discussed to reduce or prevent the occurrence of rapid reacquisition, spontaneous recovery, renewal and reinstatement after extinction. A translation to food cue exposure treatment is made and suggestions are provided, such as conducting the exposure in relevant contexts, using occasional reinforcement and targeting expectancy violation instead of habituation. A new hypothesis proposed here is that the adding of inhibition training to strengthen inhibition skills that reduce instrumental responding, might be beneficial to improve food cue exposure effects.

Expectancy violation, reduction of food cue reactivity and less eating in the absence of hunger after one food cue exposure session for overweight and obese women.

The present study investigated whether a single-session of food cue exposure for overweight women would decrease 'if CS then US' expectancies, cue reactivity and eating in the absence of hunger (EAH). EAH was measured in a behavioural paradigm that enabled to also investigate whether the cue exposure effects were specific for exposed foods or would generalise to food items that were not present during exposure. Overweight women were randomly assigned to either the cue exposure intervention or a control intervention that focused on body image. In line with the hypotheses, results showed that cue exposure induced a significant decrease in 'if CS then US' expectancies, in contrast to the control intervention. It was also found that, compared to the control intervention, desires to eat initially increased during cue exposure while gradual extinction was observed towards the end of the intervention. No extinction of increased salivation responses was found. Regarding EAH, the intake of the exposed food item was significantly less in the exposure condition than in the control condition, whereas total caloric food intake was not different between conditions, indicating that cue exposure was effective in reducing intake but did not generalise to the intake of other food items.

Food through the child's eye: An eye-tracking study on attentional bias for food in healthy-weight children and children with obesity.

OBJECTIVE: Obesity prevalence among children is high and knowledge on cognitive factors that contribute to children's reactivity to the "obesogenic" food environment could help to design effective treatment and prevention campaigns. Empirical studies in adults suggest that attention bias for food could be a risk factor for overeating. Accordingly, the current study tested if children with obesity have an elevated attention bias for food when compared to healthy-weight children. Another aim was to explore whether attention biases for food predicted weight-change after 3 and 6 months in obese children. METHOD: Obese children (n = 34) were recruited from an intervention program and tested prior to the start of this intervention. Healthy-weight children (n = 36) were recruited from local schools. First, attention biases for food were compared between children with obesity (n = 30) and matched healthy-weight children (n = 30). Second, regression analyses were conducted to test if food-related attention biases predicted weight changes after 3 and 6 months in children with obesity following a weight loss lifestyle intervention. RESULTS: Results showed that obese children did not differ from healthy-weight children in their attention bias to food. Yet automatically directing attention toward food (i.e., initial orientation bias) was related to a reduced weight loss (R² = .14, p = .032) after 6 months in children with obesity. DISCUSSION: High palatable food is a salient stimulus for all children, irrespective of their weight status. However, automatically directing attention to food cues might facilitate further weight gain in children with obesity.