Cluster analysis showed long-term cognition can be predicted by looking at regional grey matter atrophy in the first two years of multiple sclerosis course.

BACKGROUND

Grey matter (GM) atrophy is associated with cognitive impairment (CI) in multiple sclerosis (MS). We aimed to investigate the predictive role of early regional GM damage for long-term CI.

METHODS

A post-hoc cluster analysis was conducted on 175 patients with MS followed for 20 years from onset. Participants underwent a 1.5T-MRI scanning at diagnosis and after 2 years, and a comprehensive neuropsychological assessment after 20 years.

RESULTS

Three clusters have been identified: cluster 1 (primarily patients with long-term normal cognition), cluster 2 (primarily patients with long-term mild CI) and cluster 3 (primarily patients with long-term severe CI). Five brain regions have been identified showing a significant difference in early atrophy from cluster 1 and both clusters 2 and 3: precuneus (1 vs 2: p<0.001, relative risk ratio (RRR)=4.9, 95% confidence intervals (95% CIs) =2.4-10.1; 1 vs 3: p<0.001, RRR=5.5, 95% CIs=3.1-9.7), insula (1 vs 2: p<0.001, RRR=4.1, 95% CIs=1.9-8.6; 1 vs 3: p<0.001, RRR=4.3, 95% CIs=2.5-7.5), parahippocampal gyrus (1 vs 2: p<0.001, RRR=3.2, 95% CIs=1.8-5.7; 1 vs 3: p<0.001, RRR=3.1, 95% CIs=2.1-4.6), cingulate gyrus (1 vs 2: p<0.001, RRR=3.0, 95% CIs=1.7-5.3; 1 vs 3: p<0.001, RRR=2.2, 95% CIs=1.6-5.3) and cerebellum (1 vs 2: p=0.027, RRR=2.6, 95% CIs=1.5-4.6; 1 vs 3: p<0.001, RRR=2.1, 95% CIs=1.5-2.9). Four additional brain regions showed a significant difference in terms of early atrophy between cluster 1 and cluster 3: precentral gyrus (p<0.001, RRR=7.3, 95% CIs=3.1-17.3), postcentral gyrus (p<0.001, RRR=4.6, 95% CIs=2.2-9.8), superior frontal gyrus (p<0.001, RRR=4.0, 95% CIs=2.0-8.0) and hippocampus (p<0.001, RRR=2.4, 95% CIs=1.6-3.6).

CONCLUSIONS

Cluster analysis identified the most specific brain regions whose early atrophy best distinguished future patients with CI. Long-term CI accumulation in MS can be predicted by early GM volume loss of specific cortical/deep GM regions.