Metacognition in individuals with a lifetime history of anorexia nervosa: a voxel based morphometry study.

Objective: The aim of the current study was to provide a preliminary investigation of metacognition (MC) and global and regional cerebral volume in women with a lifetime history of Anorexia Nervosa (AN) compared to healthy controls (HC). In particular, we aimed to explore whether (1) MC was still affected in recovered AN patients (rec-AN) compared to HC and (2) prefrontal areas sustaining MC were morphometrically different in rec-AN compared to HC, using magnetic resonance imaging (MRI). Method: Nine adult drug-free rec-AN females (age: M=23.22; SD=+5.91) and nine adult HC (age: M=23.33; SD=+2.67) underwent the psychometric assessment consisting of the Thought Control Questionnaire (TCQ), the Metacognition Questionnaire (MCQ), the Toronto Alexithymia Scale-20 (TAS-20) and high resolution T1-weighted voxel based morphometric (VBM) MRI (224 contiguous slices, voxel size = 0.7×0.7×0.7, FOV=320×320, TR=20ms, TE=4.89ms, band = 130Hz/Px), using a 1.5 Tesla Siemens Magneton Avanto scanner. We used Voxel-Based Morphometry (VBM) to characterize brain differences in gray matter volume between the groups. Local grey matter volume (GMV) differences between the two groups were detected using a Region of Interest (ROI) analysis and a Whole Brain Analysis to strengthen and widen the ROI's results (with p<0.001). Based on the evidence regarding the neural basis of metacognition [1], masks were created around twelve areas, mainly located in the frontal lobes. Mann–Whitney test was performed to compare TCQ, MCQ and TAS-20 scores between rec-AN and HC, with α set at < 0.05. Results: The analyses revealed that rec-AN and HC did not differ for both metacognitive abilities, alexithymic traits and global GM volumes. The Region of Interest (ROI) analysis showed reduced GMVs in the right Superior Frontal Gyrus (SFG) and increased GMVs in the Temporo-Parietal Junction (TPJ) and Inferior Frontal Gyrus (IFG) in rec-AN compared to HC. Besides, the Whole Brain Analysis (WBA) found that rec-AN, compared to HC, showed reduced GMVs in the Left Superior Parietal Lobule (SPL), the Left Inferior Frontal Gyrus (IFG), the Right Inferior Occipital Gyrus (IOG), the Left Fusiform Gyrus (FG) and the cerebellum's culmen but not in the DLPFC. Conclusion: The GMV reduction seems to be aspecifically distributed in different brain areas, as found in other VBM studies which investigated adult acute and weight-restored AN patients [2,3]. Several lines of evidence sustain that frontal, parietal, temporal, occipital and cerebellar regions are involved in body shape perception, cognitive and emotional processing, which are often impaired in AN [3]. However, there was no GM decrease in brain areas specifically supporting metacognitive functioning [1], which was not compromised in rec-AN. These findings suggest that clinical recovery (i.e. achievement of adequate body weight and remission of Eating Disorder psychopathology) may accompany the restoration of neurobiological underpinnings of ‘thinking about thinking’ processes, and that MC impairment may not represent a stable marker of AN. Differences in regional GM volume may be linked to the past starvation, but whether they are state or trait is unclear. These discrete brain volume differences provide candidate brain regions for further structural and functional study in people with Eating Disorders.