Cognitive impairment and its treatment in patients with multiple sclerosis

Cognitive impairment (CI) is a relatively common manifestation of multiple sclerosis (MS), which can occur with any type of the disease course and activity. The largest CI prevalence and severity are observed in progressive MS. In relapsing-remitting MS the most prominent deterioration of cognitive functions is seen during relapses; however, in some patients it can continue also throughout remission. In a small number of patients CI can be the most significant symptom of the disease; in addition, it sometimes can be the only clinical feature of the relapse. Despite this, in clinical practice CI remains out of the focus of attention, and is not evaluated when assessing the disease severity and/or activity, while CI is not included into EDSS. Nonetheless, a number of specialized neuropsychological tests and batteries has been developed recently, which can be used for both screening and detailed assessment of CI in MS, as well as for assessment of its changes over time. CI has a negative impact on MS patients' quality of life, their social interactions, daily and occupational activities. The influence of disease-modifying agents on CI has been poorly investigated; however, there is evidence that they can reduce the degree of CI. The optimal choice of pathogenetic treatment in patients with CI remains understudied. There is no convincing evidence of the effectiveness of symptomatic pharmacological treatment of CI in MS, and cognitive rehabilitation is the only approach with confirmed effectiveness. Considering the limitations of this technique (its availability, quite a big number of sessions), there is a need to search for other methods to increase its efficacy, including non-invasive neuromodulation (in particular, transcranial direct current stimulation or transcranial magnetic stimulation). This article is focused on a brief review of the main diagnostic methods of CI in MS, its pathogenetic and symptomatic treatment, and cognitive rehabilitation techniques, as well as on the results of the studies on non-invasive neuromodulation.