Food Reward Circuit Change by Orthodontics

It has been described in obese individuals in which decreased basal metabolism as well as dopaminergic changes in the prefrontal cortex and striatum parallels the increased activation of reward brain regions in response to delicious food cues. Our aim is to explore different neurobehavioral dimensions of food choices and motivational processes in the light of this information, and to reveal whether these behaviors can be changed by operant conditioning with neuroimaging methods for phenotypes at risk.

The incidence of eating disorders in society is increasing day by day and is becoming an increasingly serious problem. Overweight people are suggested to exhibit eating behavior to cope with anxiety, depressed mood, anger and other negative emotions. Studies in humans and animals have shown that obesity is associated with changes in dopaminergic neurotransmission. Changes in brain locations associated with satiety and hunger centers (hypothalamus, hippocampal gyrus, amygdala, insula, cerebellum and midbrain) of obese patients have been shown. It has been reported that cognitive control strategies that can lead to more effective impulse control behaviors should be applied for obesity treatment, which is considered as an addiction in which food is perceived as a reward nowadays. During the first week of fixed orthodontic treatment, all the patients have pain and various discomforts with food, and after each appointment, the pain occurs while chewing. Patients declare having prolonged eating times due to difficulty in chewing, food impaction under the brackets and complains about not being able to consume sugar-containing foods due to maintain oral hygen. It is known that individuals who have eating disorders have a disturbance in their food rewarding properties and eating behavior. They eat in response to emotions rather than to meet energy needs. Pharmacological and bariatric surgical interventions are more successful than dietary lifestyle interventions because these interventions reduced not only the hunger but also the reward value of the homeostatic and hedonic brain regions of the foods. However, there is no study of whether enjoying from the food, perceiving food as a reward or individuals eating habits can be changed. The hypothesis of this study is that as a result of orthodontic treatment in which individuals experience negative emotions during each meal for two years there will be a change in the way of individuals' interpretation of food. In order to investigate this hypothesis, eating attitudes and eating habit questionnaires will be applied to healthy volunteers with a body mass index of 25 and above chosen from patients who applied to our clinic for fixed orthodontic treatment. Thus, individuals with emotional eating, externally induced eating, restrained eating disorders and eating habits of these individuals will be identified. Magnetic resonance images will be taken from 20 individuals with eating disorders before fixed orthodontic treatment, 12 months of orthodontic treatment and 6 months after orthodontic treatment finished. By means of magnetic resonance imaging (MRI) and diffusion tensor imaging (DTG), the microstructural changes in axonal and myelin structures in the tracts of the selected appetite and satiety centers in the brain will be defined. The presence of changes by the orthodontic treatment in nutritional perceptions will be measured.