Publications

Anorexia nervosa (AN) is an eating disorder characterized by a low food intake and often exceeding exercise, leading to a particularly low body × weight proportion. Patients with AN usually report less hunger than healthy controls. Endogenous endocannabinoids (eCBs), specifically the anandamide, have been associated to hunger, as a meal initiator, but research regarding AN and eCB and inconclusive. In this pilot study, we investigated plasma levels of eCB in inpatients with AN during fasting and after eating, both during the acute AN phase and after weight recovery. After an 8-hr fasting period, blood sample was collected from all participants. After that, participants were given a muffin test meal. Blood samples for the investigation of endogenous eCBs anandamide (N-arachidonoylethanolamide [AEA]) and 2-arachidonoylglycerol (2-AG) were then collected after 120 and 240 min. Participants were only allowed to eat and drink what was offered them during the research. AN reported less hunger than controls during fasting and at the end of the experiment. Also, plasma levels of AEA were significantly smaller in AN in comparison with controls in all time points. No significant difference was found for 2-AG plasma levels. After recovery, no significant difference was found for eCB levels. These findings could be interpreted as an AEA deregulation in AN before and after food intake, which persists after weight recovery. These findings may have implications to the pharmacological treatment of AN and to relapse occurring in the disorder.

Worldwide, nearly 3 million people die every year because of being overweight or obese. Although obesity is a metabolic disease, behavioral aspects are important in its etiology. Hunger changes the rewarding potential of food in normal-weight controls. In obesity, impairments related to reward processing are present, but it is not clear whether these are due to mental disorders more common among this population. Therefore, in this pilot study, we aimed at investigating whether fasting influence mood reactivity to reward in people with obesity. Women with obesity (n = 11, all mentally healthy) and normal weight controls (n = 17) were compared on a computerized monetary reward task (the wheel of fortune), using self-reports of mood and affect (e.g., PANAS and mood evaluation during the task) as dependent variables. This task was done in 2 satiety conditions, during fasting and after eating. Partially, in line with our expectation of a reduced affect and mood reactivity to monetary reward in participants with obesity accentuated by fasting, our results indicated a significant within-group difference across time (before and after the task), with monetary gains significantly improving positive affect in healthy controls (p>0.001), but not in individuals with obesity (p = 0.32). There were no significant between-group differences in positive affect before (p = 0.328) and after (p = 0.70) the task. In addition, women with obesity, compared to controls, reported more negative affect in general (p < 0.05) and less mood reactivity during the task in response to risky gains (p < 0.001) than healthy controls. The latter was independent of the level of satiety. These preliminary results suggest an impairment in mood reactivity to monetary reward in women with obesity which is not connected to the fasting state. Increasing the reinforcing potential of rewards other than food in obesity may be one target of intervention in order to verify if that could reduce overeating.

Impaired decision-making under conditions of uncertainty seems to contribute to the expression and maintenance of anorexia nervosa (AN), but it is not clear whether this impairment is a disease state that would remit with treatment, or a persisting trait in patients with AN. To examine this question, a longitudinal study was conducted in 12 female inpatients with AN (age M = 22.2, SE = 1.36), before (Time-1) and after reaching a body mass index of >17.5 kg/m2 (Time-2). Intolerance of uncertainty (IU) was assessed via a decision-making task, the wheel of fortune (WOF). Weight gain at Time-2 was accompanied with significant changes in uncertainty-related performance compared to Time-1 [(Time × Uncertainty), p < 0.05]. At Time-1, reaction times (RTs) varied in function of uncertainty, while at Time-2, uncertainty did not modulate RTs. These findings support a change in decision-making under uncertainty with successful weight-rehabilitation in AN. While IU was present in underweight patients, it became non-significant after weight restoration.

BACKGROUND: Previous studies using neuroimaging and behavioral measures reported altered reward processing in anorexia nervosa (AN). In addition, anhedonia states are frequently reported in AN, potentially due to the physiological stress produced by the permanent starvation. We investigated the effect of fasting and satiety on mood and reaction times to monetary rewards in AN patients and healthy controls. METHODS: Twenty-four participants with acute AN (BMI 14.4 (11.9-15.5) Kg/m2) and 17 age and gender matched healthy, normal weight subjects (HW) (BMI 21.8 (18.9-24.9) Kg/m2) performed a reward task (the wheel of fortune) involving uncertain (50/50 probability of winning high and low rewards), safe and risky (30/70 and 10/90 probabilities) categories in fasted (after an 8-h fasting period) and fed (after intake of a standardized meal) states. Data analysis was done with linear mixed models. RESULTS: AN reacted slower than HW when maximum uncertainty (50/50) was involved. Positive mood in response to winning was higher when fasting especially for HW, while negative mood in response to not winning was higher in the fed state for both groups. Still, HW were more reactive than AN to not winning a highly predictable monetary reward (10/90 safe). CONCLUSION: The data on the reaction times indicate an impaired motor response to uncertainty in AN. Mood reactivity to winning a monetary reward does not seem to be impaired in AN, however, our results suggest that negative mood in response to not winning is less adaptive in AN. Implications to clinical psychotherapy are discussed.

BACKGROUND: Previous studies using neuroimaging and behavioral measures reported altered reward processing in anorexia nervosa (AN). In addition, anhedonia states are frequently reported in AN, potentially due to the physiological stress produced by the permanent starvation. We investigated the effect of fasting and satiety on mood and reaction times to monetary rewards in AN patients and healthy controls. METHODS: Twenty-four participants with acute AN (BMI 14.4 (11.9-15.5) Kg/m2) and 17 age and gender matched healthy, normal weight subjects (HW) (BMI 21.8 (18.9-24.9) Kg/m2) performed a reward task (the wheel of fortune) involving uncertain (50/50 probability of winning high and low rewards), safe and risky (30/70 and 10/90 probabilities) categories in fasted (after an 8-h fasting period) and fed (after intake of a standardized meal) states. Data analysis was done with linear mixed models. RESULTS: AN reacted slower than HW when maximum uncertainty (50/50) was involved. Positive mood in response to winning was higher when fasting especially for HW, while negative mood in response to not winning was higher in the fed state for both groups. Still, HW were more reactive than AN to not winning a highly predictable monetary reward (10/90 safe). CONCLUSION: The data on the reaction times indicate an impaired motor response to uncertainty in AN. Mood reactivity to winning a monetary reward does not seem to be impaired in AN, however, our results suggest that negative mood in response to not winning is less adaptive in AN. Implications to clinical psychotherapy are discussed.