Sex Differences in Cognitive Performance in Multiple Sclerosis
Tomas Uher1, Manuela Vaneckova3, Jan Krasensky2, Jana Blahova Dusankova3, Eva Havrdova4, Dana Horakova1
1Neurology, 2Radiology, Charles University, 3Charles University, 4Neurologicka Klinika 1 LF UK
To investigate, the sex differences in cognitive performance in multiple sclerosis (MS) patients.

Although, there is some evidence showing worse cognitive functioning in male MS patients, the role of brain pathology in this context has been less studied.

This study included 1052 patients, with relapsing-remitting MS. Brain MRI and neuropsychological assessment with the Brief International Cognitive Assessment for Multiple Sclerosis (BICAMS) was performed. We used logistic regression adjusted for age, Expanded Disability Status Scale (EDSS), education and depression.
Males had similar age (37.2±8.9 vs. 38.5±8.8), education (mean: 14.8±3.1 vs. 14.7±3.0) and EDSS (median: 2.0 vs. 2.0), but shorter disease duration (mean: 8.4±6.5 vs. 10.1±7.2) and lower level of depressive symptoms (mean: 6.2±6.5 vs. 7.9±7.4) than females. The prevalence of abnormal cognitive screening (≥1 abnormal [<1.5 SD] BICAMS subtest) was slightly higher in males (30%) than females (26%). Females had higher scores in the Symbol Digit Modalities Test (SDMT) (56±11.8 vs. 54±11.0; p<0.001) and the California Verbal Learning Test Second Edition (CVLT-II) (60±11.3 vs. 54±12.1; p<0.001), but not in the Brief Visuospatial Memory Test-Revised (BVMT-R) (27.2±6.7 vs. 27.8±6.2; p>0.05). Paradoxically, females evaluated their cognitive performance as being worse than males (16.6 vs 14.5, p<0.004). Males had higher T2 lesion volume (median: 1.9 vs 1.6; p=0.01), but the same brain parenchymal fraction (median: both 85.4; p>0.05) as females. Sex differences in cognitive performance (SDMT and CVLT-II) remained significant also after adjustment for lesion burden and brain atrophy. We did not find major differences in the strength of association between cognitive and MRI measures in males and females.

Male sex was associated with slightly worse verbal memory and information processing speed. Brain MRI measures did not explain the sex difference in cognitive performance. Male sex should be considered as a risk factor for cognitive dysfunction.