Researchers from the Bellvitge Biomedical Research Institute (IDIBELL) and the University of Barcelona, ​​and CIBER in Physiopathology of Obesity and Nutrition (CIBERobn), led by Fernando Fernández-Aranda, found that patients with extreme weight conditions such as anorexia nervosa and obesity, may share certain neurobiological correlations of the reward pathways and neuronal circuits related to food. The study was published in PLoS ONE.

The identification of the common features in eating disorders and obesity with recurrent, highly palatable, as eating too much, and negative emotions related to dietary restriction has led to model these conditions as a result of an addiction to this food. Groups with extreme weight conditions can share biological risk factors and neurocognitive phenotypes. Among these, it could be remarkable the executive dysfunction, primarily characterized by changes in decision-making, not inhibit appropriate responses and show cognitive flexibility. The aim of this study was to investigate if there is a common pattern of executive dysfunction in these groups comparing patients with anorexia nervosa, obesity and control subjects.

Alterations in neuronal circuits related to motivation and reward

Neuroimaging studies indicate that alterations in dopamine circuits are involved in some eating behaviors and drug abuse. According to the authors, overeating is a sign of a disparity between the circuits related to motivation and reward (behavior) and those involved in response inhibition. In vulnerable subjects, ingestion of large amounts of food can upset the balance between circuits, increasing the reinforcing value of food and decreasing the activity related to the control circuits and inhibition, which could result in impulsive behavior and compulsive dietary intake. The participants in the study were women, aged between 18 and 60 years old. The findings suggest that subjects with extreme weight conditions show a similar pattern, which could be playing a main role in the development and maintenance of these disorders.

Anorexia nervosa is associated with alterations in attention and executive functioning, particularly in decision-making. In addition, the high impulsivity in obese subjects corroborates a dysfunctional executive profile in obesity.

Such impairments in decision-making, the inhibition response and the cognitive flexibility in patients with extreme weight conditions highlight the importance of adequate executive functioning to satisfactory control of feeding behavior.

Common characteristics between anorexia nervosa and obesity

This study aimed to examine whether these groups of patients with anorexia nervosa to obesity, have a similar profile of executive dysfunction. It was postulated that the two clinical groups should have similar executive profiles, although dysfunction may differ between them. “This is the first study to compare the profile of the executive functions of groups with extreme weight using validated measures of decision making, inhibition response and impulsivity”, says Fernández-Aranda, main researcher of the study.

The results showed a similar pattern in the executive domains assessed by neuropsychological tasks. The most marked differences were found in cognitive flexibility and decision-making, in which both anorexic patients and obese subjects showed significant difficulties. “Our results support the hypothesis that the decision-making capacity is impaired in these patients,” continues the researcher of the IDIBELL and CIBERobn.

The performance of obese subjects in these areas may be associated with a high level of impulsivity. It has been established that impulsive subjects showed limitations in learning the proper associations between reward and punishment. As a result, these individuals have a reduced ability to delay gratification, showing impulsivity characterized by overeating and weight gaining. Moreover, the behavior of the patients with anorexia nervosa and obsessive is rigid, with a high resistance to changes, in contrast with the obese patients.

“Our results not only confirm the hypothesis that obese have difficulty inhibiting automatic or dominant behavior, but also point to impulsivity and difficulties in response inhibition as a feature in the executive profile of obesity under extreme conditions of weight, “says the lead researcher.

Reference of the paper

Fagundo AB, de la Torre R, Jiménez-Murcia S, Agüera Z, Granero R, Tárrega S, Botella C, Baños R, Fernández-Real JM, Rodríguez R, Forcano L, Frühbeck G, Gómez-Ambrosi J, Tinahones FJ, Fernández-García JC, Casanueva FF, Fernández-Aranda F. (2012). Executive functions profile in extreme eating/weight conditions: from anorexia nervosa to obesity. PLoS One, 7(8): e43382. Epub 2012 Aug 21. PMID: 22927962 [PubMed – in process]