Abstract
Whereas research using structural magnetic resonance imaging (sMRI) reports sizable grey matter reductions in patients suffering from acute anorexia nervosa (AN) to be largely reversible already after short-term weight gain, many task-based and resting-state functional connectivity (RSFC) studies suggest persistent brain alterations even after long-term weight rehabilitation. First investigations into spontaneous regional brain activity using voxel-wise resting-state measures found widespread abnormalities in acute AN, but no studies have compared intrinsic brain activity properties in weight-recovered individuals with a history of AN (recAN) with healthy controls (HCs). SMRI and RSFC data were analysed from a sample of 130 female volunteers: 65 recAN and 65 pairwise age-matched HC. Cortical grey matter thickness was assessed using FreeSurfer software. Fractional amplitude of low-frequency fluctuations (fALFFs), mean-square successive difference (MSSD), regional homogeneity (ReHo), voxel-mirrored homotopic connectivity (VHMC), and degree centrality (DC) were calculated. SMRI and RSFC data were analysed from a sample of 130 female volunteers: 65 recAN and 65 pairwise age-matched HCs. Cortical grey matter thickness was assessed using FreeSurfer software. Fractional amplitude of low-frequency fluctuations (fALFF), mean-square successive difference (MSSD), regional homogeneity (ReHo), voxel-mirrored homotopic connectivity (VHMC), and degree centrality (DC) were calculated. Abnormal regional homogeneity found in acute AN seems to normalize in recAN, supporting assumptions of a state rather than a trait marker. Aberrant fALFF values in the cerebellum and the infertior temporal gyrus could possibly hint towards trait factors or a scar (the latter, e.g., from prolonged periods of undernutrition), warranting further longitudinal research.
Highlights
Anorexia nervosa (AN) is a severe mental disorder characterized by an intense fear of weight gain and a distorted body image, and patients continue to engage in dietary restriction or other behaviours to avoid weight gain despite severe undernutrition[1,2]
Group differences in Fractional amplitude of low-frequency fluctuations (fALFFs), regional homogeneity (ReHo), degree centrality (DC), voxel-mirrored homotopic connectivity (VHMC), and mean-square successive difference (MSSD) RecAN showed significantly elevated fALFF values in one cluster in the right inferior temporal gyrus and one cluster in the left cerebellum (Fig. 1). fALFF results of further analyses with alternative preprocessing methods (B: six-rigid body parameters, C: CompCor[49] method, D: with GSR; see ‘Methods’) were highly similar (Supplementary Table S2)
Previous analyses of intrinsic brain activity including ReHo and fALFF in acutely underweight AN patients using the same general study and analysis design showed widespread alterations compared to HCs29
Summary
Anorexia nervosa (AN) is a severe mental disorder characterized by an intense fear of weight gain and a distorted body image, and patients continue to engage in dietary restriction or other (compensatory) behaviours to avoid weight gain despite severe undernutrition[1,2]. Relapse rates in AN are high and long-term outcome studies generally show only low rates of full recovery[3]. Neuroimaging studies on structural data show that the widespread reductions in grey matter and alterations in white matter identified in patients suffering from acute. AN (acAN) reach normal levels already after short-term weight rehabilitation[6,7,8,9]. Research looking at task-based and resting-state functional magnetic resonance imaging (fMRI) draws a more heterogeneous picture, with some studies reporting persistent functional alterations even after long-term weight recovery[10,11,12,13,14,15,16].
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