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

How are overweight and obesity associated with reinforcement learning deficits? A systematic review

Reinforcement learning (RL) refers to the ability to learn stimulus-response or response-outcome associations relevant to the acquisition of behavioral repertoire and adaptation to the environment. Research data from correlational and case-control studies have shown that obesity is associated with impairments in RL. The aim of the present study was to systematically review how obesity and overweight are associated with RL performance. More specifically, the relationship between high body mass index (BMI) and task performance was explored through the analysis of specific RL processes associated with different physiological, computational, and behavioral manifestations. Our systematic analyses indicate that obesity might be associated with impairments in the use of aversive outcomes to change ongoing behavior, as revealed by results involving instrumental negative reinforcement and extinction/reversal learning, but further research needs to be conducted to confirm this association. Hypotheses regarding how obesity might be associated with altered RL were discussed.

CO2 reactivity is associated with individual differences in appetitive extinction memory

Pavlovian conditioning can underly the maladaptive behaviors seen in psychiatric disorders such as anxiety and addiction. In both the lab and the clinic, these responses can be attenuated through extinction learning, but often return with the passage of time, stress, or a change in context. Extinction to fear and reward cues are both subject to these return of behavior phenomena and have overlap in neurocircuitry, yet it is unknown whether they share any common predictors. The orexin system has been implicated in both fear and appetitive extinction and can be activated through a CO2 challenge. We previously found that behavioral CO2 reactivity predicts fear extinction and orexin activation. Here, we sought to extend our previous findings to determine whether CO2 reactivity might also predict extinction memory for appetitive light-food conditioning. We find that the same subcomponent of behavioral CO2 reactivity that predicted fear extinction also predicts appetitive extinction, but in the opposite direction. We show evidence that this subcomponent remains stable across two CO2 challenges, suggesting it may be a stable trait of both behavioral CO2 reactivity and appetitive extinction phenotype. Our findings further the possibility for CO2 reactivity to be used as a transdiagnostic screening tool to determine whether an individual would be a good candidate for exposure therapy.

Differences in Food Craving in Individuals With Obesity With and Without Binge Eating Disorder

Overeating behavior is supposedly a major contributing factor to weight gain and obesity. Binge eating disorder (BED) with reoccurring episodes of excessive overeating is strongly associated with obesity. Learning models of overeating behavior and BED assume that mere confrontation with food leads to a conditioned response that is experienced as food craving. Accordingly, individuals with obesity and BED were shown to have high trait food cravings. To date, little is known about differences in state food cravings and cue reactivity at the sight of palatable food in individuals with obesity and BED compared to individuals with obesity without BED. Therefore, the aim of our study was to examine differences in cue-induced, state and trait food cravings in people with obesity with and without BED. We found that all aspects of food cravings were more prevalent in individuals with obesity and BED than in individuals without BED. By implementing a food cue reactivity paradigm, our results show that individuals with obesity with BED have more cue-induced cravings than individuals with obesity without BED. Moreover, these cue-induced cravings in individuals with obesity and BED were highest for high-fat and high-sugar foods as opposed to low-calorie foods. Thus, our results emphasize the role of increased cue reactivity and craving at the sight of palatable foods in individuals with obesity and BED. Hence, our findings support etiological models of conditioned binge eating and are in line with interventions targeting cue reactivity in BED.