Understanding maladaptive reward memory in young people who binge eat: Application of novel insights from addiction
Team: Dr Sunjeev Kamboj, Dr Ravi Das, Louise Simeonov and Emma Cawley
External collaborator: Professor Ulrike Schmidt (KCL)
Adolescence and young adulthood are periods of heightened vulnerability to a variety of harmful and risky behaviours, as the brain circuits responsible for inhibiting impulsive and risky behaviours are not fully matured. Impulse control problems, and the progression to more serious compulsive-behavioural disorders characterised by harmful overconsumption (e.g. of drugs or food) are a particular concern since they account for the highest levels of preventable morbidity and mortality throughout the world. Binge eating disorder (BED) is an example of these disorders, in which the ability to resist food - or to stop eating once an episode of overeating has begun - is impaired. BED is the most prevalent eating disorder and typically begins in adolescence. However, it is a chronic problem, lasting for many years and contributing to a variety of serious psychiatric and metabolic health problems. While BED has received relatively little attention from neuroscientific researchers, there are striking parallels between BED and substance use disorders (SUDs), which also typically develop in adolescence and have been the subject of extensive basic neuroscientific, clinical and theoretical research. This has shown that abnormally strong reward memories- 'Maladaptive Reward Memories' (MRMs) - formed during drug use underlie drug craving and the propensity to seek and use drugs when 'trigger' cues are encountered. Coupled with deficits in inhibiting the responses sparked by these cues, MRMs cause continued relapse to drug use. Given the overlap in the behaviours, symptoms, age of onset and comorbidity between SUDs and BED, MRMs also likely play a key role in binge eating in response to food cues. Psychological treatments for BED often rely on the formation of alternative associations between food cues and new, more helpful behaviours. These compete with and temporarily suppress food-related MRMs.
However, such treatments do not directly weaken MRMs, and as a result MRMs typically regain dominance over time, resulting in relapse.
In contrast, recent discoveries suggest that it is possible to directly target MRMs using behavioural techniques that could readily be adapted for use in therapy for people with BED. In particular, it is possible to 'reactivate' MRMs, a process which briefly makes them unstable and pliable, and then to teach new associations that 'rewrite' the MRM into an adaptive form that does not promote relapse. This approach has now been tested in heavy drinkers, smokers and heroin users, and shown to be a very promising strategy for reducing addicts' responses to drug cues. In this project, we will apply this exciting approach to binge-eaters and determine whether similar effects are found in response to food cues and on bingeing behaviour. We will test two methods for 'overwriting' food-related MRMs, with each targeting a different neural mechanism thought to be important in BED, namely 1) reducing the ability of binge food cues to trigger craving and bingeing and 2) increasing the ability to stop food consumption triggered by these cues. By testing an 'at-risk ' population of young people, we will be targeting a developmental period when symptoms are beginning to emerge and early intervention might be expected to have an especially powerful effect, as food-related MRM networks are still relatively 'young'. Importantly, at this early stage of testing these new and potentially powerful techniques, it is essential to minimise risk to research participants. As such, our studies will be with young people who show binge eating behaviour but do not have a severe eating- or other psychological disorder. If we demonstrate evidence of overwriting of food-related MRMs and reductions in bingeing behaviour, our findings will have important treatment implications. The next step will be to adapt these experimental strategies for use in people seeking help for BED, and possibly related problems like obesity or bulimia.
This project is funded by the UK Medical Research Council