An Investigation of the Factors that Increase the Risk of Addictive-Like Eating in Adults and Children

Abstract

Overconsumption of food, particularly calorie-dense foods, has been associated with adverse health consequences, including overweight and obesity, Type II diabetes and cardiovascular issues in some individuals. Evidence indicates that overweight- and obesity-related health issues are responsible for more deaths than underweight-related health issues. However, despite the ubiquity of calorie-dense foods, an important question is why some individuals demonstrate compulsive overconsumption of food, while others are unperturbed by the availability of these foods? Previous research has outlined the role of individual differences in problematic eating, including reward sensitivity and impulsivity. Thus, a key aim of this thesis was to examine individual differences in the overconsumption of food in adults and children, which involved conducting three, independent studies, as follows: I) Study 1 was a systematic review of 45 studies that examined the relationship between reward sensitivity, impulsivity and food addiction. Results indicated that impulsivity was more frequently measured and associated with food addiction, while reward sensitivity was less associated, with a significant issue being heterogeneity in reward sensitivity measurement. II) Based on findings from Study 1, the aim of Study 2 (N= 553) was to examine the relationship between reward sensitivity and food addiction in adults using a recent measure of reward sensitivity, the Reinforcement Sensitivity Theory of Personality Questionnaire (RST-PQ). An additional aim of Study 2 was to examine the role of the two other RST systems in food addiction, behavioural inhibition (i.e., the system that handles conflict between reward and avoidance of punishment - linked to anxiety) - and fight/flight/freeze (i.e., the system responsible for avoidance of punishment, which is associated with fear). Study 2 also examined the role of gender differences in food addiction and the facets of RST. The subscales of the RST-PQ (i.e., BAS, BIS, FFFS) accounted for more variance within food addiction symptoms than measures of impulsivity (i.e., Barratt Impulsiveness Scale). BIS and FFFS accounted for additional variance in food addiction, above reward sensitivity and impulsivity. Reward sensitivity was also negatively associated with food addiction in adults. It was also revealed that women reported more food addiction symptoms in comparison to males, and that gender moderated the relationship between impulsivity and food addiction, such that this relationship was stronger in women. III) Study 3 (N=115) expanded upon the first two studies by investigating these associations within parent-child dyads. While parent (primarily mothers) impulsivity and reward were not associated with child food addiction symptoms, children characterised as impulsive and fearful by their parent showed signs of compulsive overeating/food addiction. Parenting also mediated the relationship between behavioural inhibition, impulsivity and food addiction in children, and family conflict emerged as a positive correlate of food addiction in children. The relationship between parent food addiction and child personality was also examined in Study 3. It was found that no group differences were apparent between children of parents who score highly on food addiction and children whose parents did not score highly on food addiction. Behavioural inhibition, impulsivity and fight/flight/freeze were consistently associated with food addiction across studies 2 and 3. Overall, support for the use of reward sensitivity as measured by the RST-PQ was obtained, though a negative association between reward sensitivity and food addiction in adults was found, which is contradictory to assertions made in previous research. Behavioural inhibition and fight/flight/freeze were consistently associated with food addiction across studies 2 and 3, suggesting that these mechanisms play an important role in the maintenance and predisposition of addictive-like eating in both adults and children. The results of this thesis have salient implications for the conceptualisation of addictive-like eating in adults and children, specifically that low reward sensitivity is associated with food addiction in adults, whilst impulsivity, behavioural inhibition and FFFS are relevant in both adults and children. The results of this thesis have additional implications regarding personality-targeted interventions for addictive-like eating in adults and children and reducing the morbidity and financial burden associated with disordered eating in Australia.