Anorexia nervosa and body dysmorphic disorder are associated with abnormalities in processing visual information

Abstract

Background: Anorexia nervosa (AN) and body dysmorphic disorder (BDD) are characterized by distorted body image and are frequently co-morbid with each other, although their relationship remains little studied. While there is evidence of abnormalities in visual and visuospatial processing in both disorders, no study has directly compared the two. We used two complementary modalities--event-related potentials (ERPs) and functional magnetic resonance imaging (fMRI)--to test for abnormal activity associated with early visual signaling.

Method: We acquired fMRI and ERP data in separate sessions from 15 unmedicated individuals in each of three groups (weight-restored AN, BDD, and healthy controls) while they viewed images of faces and houses of different spatial frequencies. We used joint independent component analyses to compare activity in visual systems.

Results: AN and BDD groups demonstrated similar hypoactivity in early secondary visual processing regions and the dorsal visual stream when viewing low spatial frequency faces, linked to the N170 component, as well as in early secondary visual processing regions when viewing low spatial frequency houses, linked to the P100 component. Additionally, the BDD group exhibited hyperactivity in fusiform cortex when viewing high spatial frequency houses, linked to the N170 component. Greater activity in this component was associated with lower attractiveness ratings of faces.

Conclusions: Results provide preliminary evidence of similar abnormal spatiotemporal activation in AN and BDD for configural/holistic information for appearance- and non-appearance-related stimuli. This suggests a common phenotype of abnormal early visual system functioning, which may contribute to perceptual distortions.

Keywords: Dorsal/ventral visual streams; electroencephalography; event-related potential; face processing; house processing; joint ICA.

Fig. 1

Left: Example stimuli used in the experiment, consisting of digital images filtered to normal, high, and low spatial frequencies. Right: Task paradigm, consisting of a face- or house-matching task.

Fig. 2

N170 joint component for LSF face stimuli. The BDD group (green) demonstrated hypoactivity (p<.016) compared with healthy controls in regions including lateral occipital cortex, occipital pole, and precuneus. The AN group (blue) demonstrated hypoactivity (p<.016) compared with healthy controls in the precuneus and the lateral occipital cortex. See table S4 for local max coordinates.

Fig. 3

P100 joint component for LSF house stimuli. The BDD group (green) and the AN group (blue) both demonstrated hypoactivity (p<.016) compared with healthy controls in regions including the middle temporal gyrus, the occipital fusiform gyrus, and the inferior temporal gyrus. See table S5 for local max coordinates.

Fig. 4

N170 joint component for HSF house stimuli. The BDD group (red) demonstrated hyperactivity (p<.016) in regions including the temporal fusiform cortex compared with healthy controls. See table S6 for local max coordinates.

Fig. 5

N170 joint component for LSF house stimuli. The BDD group (green) demonstrated hypoactivity (p<.016) compared with healthy controls in regions including the occipital fusiform cortex, lateral occipital cortex, and frontal pole. See table S7 for local max coordinates.

Fig. 6

N170 joint component for LSF house stimuli using a lower statistical threshold (p<.05). The BDD group (green) demonstrated hypoactivity compared with healthy controls in regions including the occipital fusiform cortex, lateral occipital cortex, and frontal pole. The AN group (blue) demonstrated hypoactivity in occipital fusiform cortex, occipital pole, and precuneus.

Figure 7

A) Scatterplot showing significant negative correlation (q=.035 after FDR correction) between mean activation map intensities and attractiveness ratings for the BDD group for HSF houses in the joint N170 component. B) Scatterplot showing negative correlation (p=.04) between mean activation map intensities and EDE ratings for the AN group for LSF faces in the joint N170 component. The correlation was not significant after multiple comparison correction.