Influence of implicit and explicit priming on nutritional fat habits and underlying neuronal networks.
Final Report Abstract
Food choice and intake is a daily and throughout normal subject. However, for more and more people eating habits and the question of food choice are of increasing interest and in several cases even a problem. The prevalence of obesity has tripled in the last decades and it is even spoken of an obesity epidemic. Lifestyle interventions to lose weight often fail on the long run, also because people fall back into former unhealthy eating habits. Various factors influence our daily food choice, not all of which are apparent to ourselves. Thus, food choice might be goal-directed and therefore conscious and reflective, yet in other circumstances the choice to eat something specific might be based on eating habits which are automatic processes and thus difficult to control. Since a change in eating-behaviour and longlasting weight loss is most problematic to achieve, the current study aimed to investigate implicit and explicit priming paradigms for changing habit-based and goal-directed nutritional behaviour. For this, three studies were performed. In a first study, the concept of explicit mindset priming (health mindset vs. palatability mindset) and implicit priming (trigger for healthy/palatable vs. trigger for unhealthy/ not palatable) was investigated combined with a well-established Pavlovian-to-Instrumental Transfer (PIT) task to test goal-directed and habit-based behaviour. Here we showed in two cohorts that our task design can be reproducibly used to induce a PIT effect also in combination with a mindset priming and implicit priming (triggers). Implicit triggers showed a replicable effect of increased response behaviour towards unhealthy food once the trigger was presented which was previously associated with unhealthy and decreased responses for unhealthy food once the trigger associated with healthy was presented. In a second study, the impact of fundamental weight loss induced by bariatric surgery on goal-directed and habitbased eating behaviour was targeted showing a stable PIT and trigger effect also in a severely obese group. Interestingly, these effects were reduced after substantial weight loss several months after bariatric surgery. To further investigate this effect a follow up after several years would be of interest. In the third study, underlying neuronal correlates of implicit priming and mindset priming on goaldirected and habit-based eating behaviour was investigated in a normal-weight and an obese group using functional magnetic resonance imaging measurements. As in previous cohorts, the most prominent behavioural effects (besides a strong PIT effect) were induced by the healthy and unhealthy triggers. Underlying neuronal activation patterns were observed in higher cognitive regions especially associated with cognitive and memory functions (hippocampus), arousal and valence (amygdala) as well as food reward processes (orbitofrontal cortex, insular cortex, putamen, rolandic operculum). These results support the notion that habitual food choices are associated and maybe even driven by neuronal processes which represent the food reward and valence aspect of implicit food cues. The major pitfall of the study was the COVID pandemic, which significantly hampered recruitment for the second and third studies. As a result, the target number of participants could not be achieved in these two studies. Nevertheless, we were also able to test the replicability of the task design in a severely obese cohort, showing exploratory longitudinal results after weight loss and the transfer to a scanner setting in a normal-weight and obese cohort. Overall, we can conclude that the task leads to strong effects of Pavlovian stimuli in normalweight and obese participants and can even be transferred into an imaging setting. The most pronounced effect could be induced by implicitly associated triggers (healthy vs. unhealthy). These results once again illustrate the influence of an obesogenic environment on food choices and highlight the influence of the implicit nature of many stimuli that shape our eating behaviour.
Publications
-
Competing influences on healthy food choices: Mindsetting versus contextual food cues. Appetite, 166, 105476.
Frank-Podlech, Sabine; Watson, Poppy; Verhoeven, Aukje A.C.; Stegmaier, Sophia; Preissl, Hubert & de Wit, Sanne
