Anorexia nervosa and diffusion weighted imaging: An open methodological question raised by a systematic review and a fractional anisotropy anatomical likelihood estimation meta‐analysis

Abstract

Background Anorexia nervosa (AN) is characterized by white matter abnormalities in neuroimaging studies. Fractional anisotropy (FA) is a diffusion tensor imaging (DTI) index that is considered an instrument for the evaluation of white matter alterations. However, the literature has recently pointed out the role of the partial volume effect (PVE) as a confounding factor for the identification of juxtaposed tissues. Our goal was to review the DTI literature in AN and evaluate possible confounding factors linked to the reported results. Method A systematic review of the literature was conducted to identify Diffusion Tensor Imaging studies of individuals with AN and, subsequently, an anatomical likelihood estimation (ALE) meta‐analysis was performed on studies published before March 18, 2019. Results Twenty‐four studies (AN = 517, controls = 542) were included in the qualitative systematic review of the literature. Ten published studies underwent the ALE‐analysis (AN = 210, controls = 229), plus data from an unpublished cohort (AN = 38, controls = 38). Two clusters of decreased FA were identified, namely in the left corona radiata, and in the left thalamus. Only one article took the PVE correction analysis into account. Conclusions The alterations identified must be considered within the limits of a possible methodological bias regarding PVE and free water and re‐analysis of the data may be recommended. The preliminary data showed that the alteration of white matter pathways between the limbic structures and brain cortex may be linked to the processing of somatosensory information that could play a key role in the psychopathology of the disorder.

Shift Toward Randomness in Brain Networks of Patients With Anorexia Nervosa: The Role of Malnutrition

“…However, the cross-sectional nature of our observations does not allow us to understand whether the observed alterations precede the onset of AN or represent a consequence of the disorder. Moreover, in the computation, we did not control for the potential bias of the partial volume effect and free water due to ventricular enlargement (Kaufmann et al, 2017;Meneguzzo et al, 2019), which, however, are not likely to have a significant effect on the global architecture of the network and on the observed regional alterations.…”

Neuroimaging Findings in Adolescents and Young Adults with Anorexia Nervosa: A Systematic Review

“…In the first one, the quantitative voxel-based meta-analysis identified decreased FA in the posterior areas of the corpus callosum, the left superior longitudinal fasciculus (SLF) II and the left precentral gyrus as well as increased FA in the right corticospinal projections and lingual gyrus [31]. In the second one, Meneguzzo et al identified two clusters of decreased FA, in the left corona radiata and in the left thalamus [32]. Finally, more recently, Zhang et al analyzed DTI studies using tractbased spatial statistics (TBSS) and reported lower FA in the corpus callosum and the cingulum [33].…”

Structural brain changes in severe and enduring anorexia nervosa: A multimodal magnetic resonance imaging study of gray matter volume, cortical thickness, and white matter integrity

“…A meta-analysis of DTI studies reported that the fractional anisotropy (FA), an indicator of WM integrity, was decreased in the fornix, cingulum, fronto-occipital tract (Monzon et al, 2016), thalamo-cortical tract, and occipital-parietal-temporal-frontal tract (Gaudio et al, 2019). In addition, a systematic review showed decreased FA in the left corona radiata and thalamus (Meneguzzo et al, 2019). Although the number of studies is increasing, results have been inconsistent within imaging modalities, and no convincing interpretations regarding the relationship between regional brain changes and AN pathophysiology have been presented.…”