In patients with multiple sclerosis (MS), the cognitive reserve (CR) and the brain reserve (BR) can reduce the effect of gray matter atrophy on classical or social cognition, with stronger protective effects observed in the early stages of MS, according to the study published in Multiple Sclerosis and Allied Disorders.
Previous studies focused on cognitive deficits in classic areas, including complex attention, working memory, speed of information processing, learning, and executive functions. However, there are limited data on social cognition in patients with MS. The aim of the current cross-sectional study was to determine the influence of CR and BR on social cognition in MS patients.
The sample consisted of 60 patients with MS (age 18-55 years) and 60 age-, gender- and education-adjusted healthy controls. Of these, 34 patients with MS (56.7%) were cognitively impaired.
All participants underwent clinical evaluation and detailed neurological examination, a series of neuropsychological tests, as well as ToM (Theory of Mind) tests, defined as the ability to infer other people’s mental states and predict behavior. In addition, all participants completed a 3Tesla brain MRI. Study researchers rated the cortical and subcortical gray matter volumes of the patients. The rating of CR was determined based on education while using intracranial volume (ICV) as a proxy for BR.
Participants with MS had lower scores in both ToM tasks than those in the healthy control group: eye test (58.7% versus 81.9%; P <0.001) and video test (75.3% versus 88.1%; P. < 0.001).
Total gray matter volume (37.6 versus 39.8; P <0.001), cortical gray matter volume (28 versus 29.4; P = 0.002), subcortical gray matter volume (3.40 versus 3.80; P. <0.001); and white matter volumes (28.0 versus 29.8; P <0.001) were lower in patients with MS than in the healthy controls. There was no correlation between education and ICV in patients in either group.
According to statistical analysis, education was an independent predictor of overall cognitive status. Patients with higher education had better cognitive status (R2, 0.088; P = 0.005). There was a significant interaction between gray matter education and subcortical volume (R2, 0.219; P <0.001) as higher education reduced the negative effects of gray matter atrophy on cognitive function.
In addition, there was a significant interaction between ICV and cortical gray matter volume, as a larger ICV was associated with superior performance in social cognitive tests and mitigated the negative effects of GM cortical atrophy on them. However, CR had no significant effect.
The protective effects of education and ICV have been indicated in the early stages of the disease, mainly in patients with disease duration of less than 10 years.
The study had several limitations, including the cross-sectional design, the use of proxies to assess reserve, and assessing social cognitive skills based on tests that were not specifically validated for MS patients.
“The results obtained in this study confirm that both CR and BR play a protective role in the perception of MS patients and reduce the negative effects of GM [gray matter] Atrophy, ”concluded the study researchers.
Disclosure: Several authors on the study stated links to the pharmaceutical industry. For a full list of the authors’ information, see the original reference.
Machado R., Lima C., d’Almeida OC, et al. Protective effect of the cognitive and brain reserves in multiple sclerosis. Mult Scler Relat Disord. Published online on December 26, 2020. doi: 10.1016 / j.msard.2020.102716