There is growing evidence of 'food addiction' (FA) in sugar- and fat-bingeing animals. The purpose of this study was to investigate the legitimacy of this disorder in the human condition. It was also our intention to extend the validation of the Yale Food Addiction Scale (YFAS) - the first tool developed to identify individuals with addictive tendencies towards food. Using a sample of obese adults (aged 25-45 years), and a case-control methodology, we focused our assessments on three domains relevant to the characterization of conventional substance-dependence disorders: clinical co-morbidities, psychological risk factors, and abnormal motivation for the addictive substance. Results were strongly supportive of the FA construct and validation of the YFAS. Those who met the diagnostic criteria for FA had a significantly greater co-morbidity with Binge Eating Disorder, depression, and attention-deficit/hyperactivity disorder compared to their age- and weight-equivalent counterparts. Those with FA were also more impulsive and displayed greater emotional reactivity than obese controls. They also displayed greater food cravings and the tendency to 'self-soothe' with food. These findings advance the quest to identify clinically relevant subtypes of obesity that may possess different vulnerabilities to environmental risk factors, and thereby could inform more personalized treatment approaches for those who struggle with overeating and weight gain.
Evidence that 'food addiction' is a valid phenotype of obesity
Davis, C., Curtis, C., Levitan, R. D., Carter, J. C., Kaplan, A. S., & Kennedy, J. L
Food addiction was assessed by the 25-item Yale Food Addiction Scale [YFAS]. Binge Eating Disorder [BED] was diagnosed using ratings on the Eating Disorder Examination. Depression severity was assessed by the 21-item, Beck Depression Inventory. ADHD symptoms were assessed by two self-report inventories: the 5-point Wender Utah Rating Scale [WURS-25] and the Conners’ Adult ADHD Rating Scale – Self-report Screening Version (CAARS-SSV). Impulsivity was assessed by the 30-item Barratt Impulsivity Scale [BIS] and two computerized behavioural measures: the Delay Discounting Task and The Delay of Gratification Task. Addictive personality traits were assessed by the 32-item Addiction Scale of the Eysenck Personality Questionnaire-Revised [EPQ-R]. Binge eating was assessed by 5-items of the Binge Eating Questionnaire and Hedonic eating was assessed by the Power of Food Scale. Emotional eating and externally driven eating were assessed by the Dutch Eating Behaviour Questionniare [DEBQ]. Food cravings were assessed by the Food Craving Questionnaire. Snacking on sweets was assessed by the 6-item subscale of the Eating Behaviour’s Patterns Questionnaire.
49 obese adult premenopausal women and 23 men between the ages of 25-46 years took part in the study. Exclusion criteria included a current diagnosis of a psychotic disorder, substance abuse, alcoholism, or a serious medical/physical illness such as cancer, heart disease, or paralysis.
According to the YFAS diagnostic scoring procedure, 18 adults (female = 13; male = 5) were classified as food addicts. Compared to their non-food addict counterparts, the group of food addicts did not differ significantly in age, BMI, gender ratio, ethnic composition, or education level between the two groups. Among the food addicts, a significantly greater proportion was diagnosed with BED and had a higher prevalence of severe depression. A greater proportion of this group also met the criteria for a probable diagnosis of childhood ADHD. Multivariate analysis of variance (MANOVA) was used to compare food addicts and non-food addicts on relevant personality characteristics. Food addicts reported more impulsive traits on the BIS and showed poorer performance on the delay of gratification and delay discounting tasks. They also had significantly higher scores on the measure of addictive personality traits. Food addicts reported more binge eating, hedonic eating, and emotionally driven eating. They also reported greater food cravings and snacking on sweets. Although we found considerable overlap between FA and BED, it was also clear that the two conditions are distinguishable. In parallel with other addiction disorders, there was also more severe depression and greater childhood symptoms of ADHD in the FA group compared to their non-FA counterparts. These associations mesh well with the view that a common underlying process contributes to the increased risk for disorders like depression, ADHD, and addiction, all of which are known to be mesolimbic dopamine-deregulated conditions. While low brain dopamine levels may be an inherited trait in some individuals, there is also very good evidence that prenatal and early postnatal life present ‘‘windows of susceptibility’’ to the deleterious effects of stress (in the form of abuse and neglect) on the brain development crucially necessary for optimal dopaminergic functioning. Food addicts demonstrated impulsivity. Our measure of addiction proneness was also significantly higher in the FA participants. Indeed, this variable accounted for the greatest variance in YFAS symptom scores, indicating its centrality as a risk factor for FA. Therefore, high scores tend to reflect elevated levels of emotional reactivity, proneness to stress, and negative affect. Of relevance to our findings is the high co-morbidity between anxiety disorders and addiction disorders. The powerful urges and cravings that compel drug seeking behaviours – often against the individual’s better judgement – are cardinal features of all addiction disorders. As expected, the food addicts reported stronger food cravings than the non-FA group. Food addicts were more sensitive and responsive to the pleasurable properties of palatable foods as indicated by higher scores on a measure of the hedonic impact of food, and by more frequent snacking on sweets. We found that food addicts reported more overeating in response to emotional triggers like depression and anxiety, and were more likely to self-soothe with food compared to control participants.
Davis, C., Curtis, C., Levitan, R. D., Carter, J. C., Kaplan, A. S., & Kennedy, J. L. (2011). Evidence that “food addiction” is a valid phenotype of obesity. Appetite, 57(3), 711–717. doi:10.1016/j.appet.2011.08.017