[Anorexia nervosa in the light of neurocognitive functioning: New theoretical and therapeutic perspectives]

Abstract

Introduction: Anorexia nervosa is a serious psychiatric disorder, for which very few validated therapeutic strategies exist. The specific sociocognitive style of anorexic patients has already been described in the 1960s: it involves a concrete style with abstraction difficulties. Current neuropsychological tests have contributed to a more precise definition of these difficulties.

Neuropsychological data: IS THERE A SPECIFIC COGNITIVE PROFILE?: Contrary to common beliefs, these patients' intellectual performances are not superior to those of the general population. However, detailed comparisons of profiles on the Weschler Scales suggest difficulties in synthesizing information and better abilities in concrete problem solving.

Excessive attention to details: The dominant hypothesis concerning the attentional dimension is the existence of a weakness in central coherence, resulting in superior detail processing and a weakness in global integration. This trend appears to be stable even after the normalization of nutritional status.

Impaired cognitive flexibility: The impairment of set-shifting abilities leads to rigidity, expressed by inflexibility and perseveration, both in reasoning and behaviour. This reduced cognitive flexibility appears to persist after recovery, and may constitute a familial trait. In addition, this likely endophenotype seems to be independent from obsessional traits.

Controversial social skill: Alexithymia is frequently described in anorexic individuals. It is the verbal description of feelings which seems to be particularly impaired. It may explain underlying difficulties in empathy. Indeed, these subjects have lower scores on emotional tests drawn from the theory of mind. These cognitive abnormalities are well documented in pervasive developmental disorders. NEUROANATOMICAL DATA: NEUROIMAGING IN SUPPORT OF LIMBIC AND FRONTO-STRIATAL ABNORMALITIES: Evidence from neuroimaging suggests abnormalities in cortical and subcortical structures, involving the temporal and orbito-frontal lobes. Various functional hypotheses are formulated, involving fronto-striatothalamic circuits, amygdala or insula. IS ANOREXIA NERVOSA A DEVELOPMENTAL DISORDER?: Pervasive developmental disorders are over-represented among anorexic subjects in comparison to the general population. Conversely, restrictive and selective eating disorders are more frequent among individuals presenting an autistic spectrum disorder.

Therapeutic implications and future directions: In view of the common cognitive and neuroanatomical data that are found in anorexia nervosa and neurodevelopmental disorders, we adhere to the hypothesis that anorexia nervosa may be similar to a neurodevelopmental disorder. Clinical observations suggest that this hypothesis may be especially relevant in the early forms of anorexia nervosa. These cognitive data confirm the potential relevance of new therapeutic modalities such as cognitive remediation. Initial results from its application to anorexia nervosa seem promising.

Conclusion: A review of the recent literature highlights the possible existence of a developmental impairment of cortical and subcortical structures, associated with specific abnormalities in cognitive development such as a weakness in central coherence, reduced set-shifting ability and poor social skills. On this basis, cognitive remediation may be a promising therapeutic innovation.

Keywords: Anorexia nervosa; Anorexie mentale; Cognitif; Cognitive science; Cognitive therapy; Developmental disabilities; Imaging; Neuro-imagerie; Remédiation cognitive; Trouble envahissant du développement.