Neurocognitive impairment is frequently encountered in Multiple Sclerosis (MS) patients affecting between 40-65% of these individuals, irrespective of disease duration, severity of physical disability, and at both the earlier and later disease stages, with a tendency to worsen over time. Moreover, cognitive dysfunction in this population may have a significant negative impact on quality of life, activities of daily living, independence and employment status.
Although several neuropsychological studies have compared the cognitive functions of patients between the three conventional clinical types (Relapsing Remitting - RRMS, Secondary - Progressive - SPMS and Primary Progressive - PPMS), results have been contradictory regarding neurocognitive deficit severity and pattern. The article by Ntoskou et al., provides further evidence that MS patients irrespective of clinical subtype, disease duration and severity, present with cognitive deficits compared to demographically and intellectually matched healthy individuals. Moreover, the study found that when MS patients convert from RRMS to SPMS, their cognitive abilities decline. Although they do not differ on overall global cognitive function, they differ on important cognitive abilities such as learning new information, speed of mental processing, ability to inhibit overlearned responses and mental flexibility. These cognitive deficits have a significant impact on everyday functioning abilities and quality of life. Contrary to the findings noted by the study regarding neurocognitive differences in terms of severity (quantitative) between the RRMS and SPMS patients, the pattern of impairment (qualitative) remains relatively stable, i.e. both patient types have impaired new learning and episodic memory, mental processing speed and executive dysfunction.