Cognitive impairment (CI) is a common and disabling symptom in MS. Several magnetic resonance imaging (MRI) studies have shown that thalamus, among other gray matter (GM) structures, is the most relevant for cognitive performance in MS.

To assess the relationship between thalamic regional volumes/shape and performance in global/specific cognitive domains in multiple sclerosis (MS).

One hundred and eighteen relapsing remitting MS (RRMS) patients and 52 sex, age and education-matched healthy controls (HC) underwent an extensive neuropsychological assessment, through Brief Repeatable Battery of Neuropsychological Tests (BRB) and Stroop Test, and a 3T–MRI protocol including high resolution 3D–T1 imaging.  Thalamic volumes were calculated using FIRST tool of the FMRIB Software Library. A vertex analysis of thalamic shape was also performed, exploring regional differences between MS and HC. Correlation analyses were run between performance in global/specific cognitive domains and thalamic changes in shape/volume. Thalamic connectivity-defined subregions showing significant changes were labeled using an atlas previously derived that includes probability maps of thalamic parcellation in frontal, motor, parietal, occipital, and temporal connectivity defined regions.

Compared to HC, MS patients showed a significant atrophy (p<0.01) in the whole thalamus. Considering the correlation analyses between global/specific cognitive performance and thalamic volume/shape: 1) attention/information processing speed performance correlated (p<0.01) with atrophy of bilateral frontal-connected and right (R) motor-connected thalamic subregions; 2) verbal fluency performance correlated (p=0.05) with atrophy of  left (L) all thalamus subregions and R frontal/temporal-connected thalamic subregions; 3) executive functions performance correlated (p<0.01)  with atrophy of all thalamus subregions, bilaterally; 4) global cognitive status correlated (p<0.01) with atrophy  of L frontal/temporal-connected subregions.

This study further confirms that the thalamus is relevant for cognitive status in MS. Furthermore, patterns of regional changes in thalamic shape/volume are relevant for performance in specific cognitive domains in MS.