Prevalence of Cognitive Impairment in Newly Diagnosed Relapsing-Remitting Multiple Sclerosis.

Background: Cognitive impairment is common in multiple sclerosis (MS) and can manifest early in the disease process, sometimes as early as the first demyelinating event. However, the frequency of cognitive impairment in a newly diagnosed MS population has not been evaluated comprehensively in a clinical population. We sought to examine the prevalence of cognitive impairment in relapsing-remitting MS (RRMS) within a year of diagnosis in a clinic where cognitive testing at diagnosis is part of routine practice.

Methods: A retrospective medical record review of persons with RRMS assessed in a cognitive MS clinic identified 107 patients assessed by the Minimal Assessment of Cognitive Function in Multiple Sclerosis battery within 1 year of a confirmed RRMS diagnosis.

Results: The cohort was predominantly female (n = 82 [76.6%]) and white (n = 93 [86.9%]). Only 36 patients (33.6%) were diagnosed as having RRMS based on a second clinical event. Processing speed was the most frequently impaired domain (n = 38 [35.5%]). Only 37 patients (34.6%) were within normal limits on all cognitive domains. Regarding mood symptoms, 25 patients (23.4%) were positive for depressive symptoms; 59 (55.1%), for anxiety. Severe fatigue was correlated with a lower score on the Symbol Digit Modalities Test (SDMT) (r = -0.380, P < .001), and higher depressive scores were correlated with lower performance on the SDMT (r = -0.397, P < .001) and the Paced Auditory Serial Addition Test (r = -0.254, P = .009).

Conclusions: Cognitive impairment, specifically processing speed, and mood symptoms are frequently present in persons with newly diagnosed RRMS.