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, 25, 29-36

An MRI Evaluation of Grey Matter Damage in African Americans With MS


An MRI Evaluation of Grey Matter Damage in African Americans With MS

Maria Petracca et al. Mult Scler Relat Disord.


Objective: Multiple sclerosis (MS) is less prevalent in African Americans (AAs) than Caucasians (CAs) but in the former the disease course tends to be more severe. In order to clarify the MRI correlates of disease severity in AAs, we performed a multimodal brain MRI study to comprehensively assess the extent of grey matter (GM) damage and the degree of functional adaptation to structural damage in AAs with MS.

Methods: In this cross-sectional study, we characterized GM damage in terms of focal lesions and volume loss and functional adaptation during the execution of a simple motor task on a sample of 20 AAs and 20 CAs with MS and 20 healthy controls (CTRLs).

Results: In AAs, we observed a wider range of EDSS scores than CAs, with multisystem involvement being more likely in AAs (p < 0.01). While no significant differences were detected in lesion loads and global brain volumes, AAs showed regional atrophy in the posterior lobules of cerebellum, temporo-occipital and frontal regions in comparison with CAs (p < 0.01), with cerebellar atrophy being the best metric in differentiating AAs from CAs (p = 0.007, AUC = 0.96 and p = 0.005, AUC = 0.96, respectively for right and left cerebellar clusters). In AAs, the functional analysis of cortical activations showed an increase in task-related activation of areas involved in high level processing and a decreased activation in the medial prefrontal cortex compared to CAs.

Interpretation: In our study, the direct comparison of AAs and CAs points to cerebellar atrophy as the main difference between subgroups.

Keywords: African Americans; Grey matter; Multiple Sclerosis.

Conflict of interest statement

Potential conflicts of interest

Nothing to report.


Figure 1.
Figure 1.
White matter and grey matter lesion probability maps in African American and Caucasian MS patients, overlaid on the MNI standard brain template, showing the probability of each voxel to contain a lesion in each racial subgroup (p<0.05, TCFE corrected for multiple comparisons). Peaks of WM and GM lesion frequency are identified by crosshairs. The color scale denotes the probability range. Abbreviations: AAs=African-American; CAs=Caucasians; WM=white matter; GM=grey matter; LPM=lesion probability map.
Figure 2.
Figure 2.
Results of the Voxel Based Morphometry analysis showing significant differences between groups. Areas of relative GM reduction in African American MS patients compared to controls (A), Caucasian MS patients compared to controls (B) and African American compared to Caucasian patients (C) are showed in red, overlaid on the 3D brain surface rendering of a single normal subject provided in SPM12 (p<0.01, FWE-corrected at cluster level).
Figure 3.
Figure 3.
Relative activations during the performance of the motor task in African-American patients vs. controls (A), Caucasian patients vs. controls (B) and African-American vs. Caucasian patients (C). Clusters showing a significant difference in activation are shown overlaid on the MNI standard brain template (p<0.05, cluster corrected for multiple comparisons). The color scale represents the Z value.

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