Anomalous Lateral Dominance Patterns in Women with Eating Disorders: Clues to Neurobiological Bases

The song of Anorexia Nervosa: a specific evoked potential response to musical stimuli in affected participants

PURPOSE

Research applying electroencephalography (EEG) to Anorexia Nervosa (AN) is still limited, even though in other psychiatric disorders EEG has permitted to find out the hallmarks of the disorder. The aim of the study was to explore whether EEG basal activity and reactivity to musical stimulation differ in participants with AN as compared to healthy subjects (HS).

METHODS

Twenty female participants (respectively 10 with AN and 10 healthy controls) were administered a battery of psychometric tests and underwent EEG under three different conditions: (1) at baseline; (2) after a generic music stimulation; and (3) after a favorite musical stimulation.

RESULTS

In participants with AN, basal EEG showed the higher absolute amplitude of cortical slow waves (theta) in the parieto-occipital and temporal derivations, with a deficit in the beta band. In AN, there was a higher N100 latency and a reduced P300 latency compared to HS. While the N100 and P300 latencies were sensitive to the musical stimulus in HS, there was no difference after music stimulation in AN.

CONCLUSION

These data suggest that AN is accompanied by a state of brain hyperarousal with abnormal reactivity to environmental stimuli, similar to the state of HS after musical stimulation. If confirmed, this finding may have treatment implications.

LEVEL OF EVIDENCE

III, Evidence obtained from well-designed cohort or case-control analytic studies.

Visual processing in anorexia nervosa and body dysmorphic disorder: similarities, differences, and future research directions

Anorexia nervosa (AN) and body dysmorphic disorder (BDD) are psychiatric disorders that involve distortion of the experience of one's physical appearance. In AN, individuals believe that they are overweight, perceive their body as "fat," and are preoccupied with maintaining a low body weight. In BDD, individuals are preoccupied with misperceived defects in physical appearance, most often of the face. Distorted visual perception may contribute to these cardinal symptoms, and may be a common underlying phenotype. This review surveys the current literature on visual processing in AN and BDD, addressing lower- to higher-order stages of visual information processing and perception. We focus on peer-reviewed studies of AN and BDD that address ophthalmologic abnormalities, basic neural processing of visual input, integration of visual input with other systems, neuropsychological tests of visual processing, and representations of whole percepts (such as images of faces, bodies, and other objects). The literature suggests a pattern in both groups of over-attention to detail, reduced processing of global features, and a tendency to focus on symptom-specific details in their own images (body parts in AN, facial features in BDD), with cognitive strategy at least partially mediating the abnormalities. Visuospatial abnormalities were also evident when viewing images of others and for non-appearance related stimuli. Unfortunately no study has directly compared AN and BDD, and most studies were not designed to disentangle disease-related emotional responses from lower-order visual processing. We make recommendations for future studies to improve the understanding of visual processing abnormalities in AN and BDD.

Neuropsychological psychopathology measures in women with eating disorders, their healthy sisters, and nonrelated healthy controls

OBJECTIVE

To assess the familial influence on neuropsychological dysfunction in eating disorders (ED) patients by comparing 16 patients with restricting type anorexia nervosa (AN-R), 18 patients with bingeing purging type anorexia nervosa, 20 patients with bulimia nervosa binge-purge type, 21 of the patients' nonaffected sisters, and 20 nonrelated healthy controls.

METHODS

Self-report questionnaires assessing psychopathology and 2 computerized cognitive tasks measuring hemispheric asymmetry for language and visuospatial abilities were administered to all participant groups.

RESULTS

On the self-report questionnaires, ED patients scored significantly more pathological than the healthy controls, whereas the healthy sisters were similar to the nonrelated healthy control group. For both of the computerized tasks, the behavior pattern of the sisters was similar to that of all, or most ED groups, and were significantly different from the nonrelated healthy controls. In addition, AN-R patients performed significantly worse on the visuospatial task than the other ED groups.

CONCLUSIONS

The dissociation between the performance on the cognitive tasks and psychopathology measures in healthy sisters, when compared to the ED and nonrelated healthy control groups, suggests that disturbances in neurocognitive functioning in ED patients are not necessarily the result of ED-related dysfunction. Rather, this may indicate general individual differences in cognitive processes that may run in families irrespective of the ED condition of the family member. The findings, with respect to the AN-R patients, support a neurocognitive continuum model of EDs in which AN-R represents the most severe form of the illness.

Transcranial direct current stimulation in the treatment of anorexia

Transcranial direct current stimulation (tDCS) is a non-invasive technique for brain stimulation and it increasingly being used in the treatments of some neurological/psychiatric conditions (e.g. chronic pain, epilepsy, depression, motor rehabilitation after stroke and Parkinson's disease). With tDCS, cortical neurons excitability increases in the vicinity of the anodal electrode and suppressed near the cathodal electrode. There is evidence that anorexia is associated with hyperactivity in right-hemisphere frontal regions. tDCS, therefore has a promising potential in facilitating inter-hemispheric balance. A tDCS protocol is proposed: the anode electrode placed over the left prefrontal cortex and the cathode electrode located, either on the right homotopic region for non-SSRI-medicated anorexics, or on a non-cephalic site for SSRI-medicated anorexics. Together with nutritional supplements, psychotherapy and other treatments, tDCS have a good potential, as a complementary tool, in the treatment of anorexia.