The role of disability and depression in cognitive functioning within 2 years after multiple sclerosis diagnosis
Objectives: To investigate cognitive functioning shortly after multiple sclerosis (MS) diagnosis and to examine the relationship with disability, depression and anxiety. Methods: Data were available for 101 recently diagnosed MS patients and 117 healthy controls. Neuropsychological and clinical assessment included Rao's Brief Repeatable Battery, Expanded Disability Status Scale (EDSS), and Hospital Anxiety and Depression scale (HADS). Results: Patients had lower scores than controls on timed tasks (Paced Auditory Serial Addition Test (PASAT3, p-value adjusted for age, sex and education = 0.04; PASAT2, p = 0.001), Word List Generation Test (WLG, p = 0.04)). Scores on Symbol Digit Modalities Test (SDMT; p = 0.001), PASAT3 (p = 0.01) and PASAT2 (p < 0.001) showed significant association with EDSS. Patients with EDSS ≥ 3.0 had significantly lower scores on Selective Reminding Test (SRTC, p = 0.04), SDMT (p = 0.002), PASAT3 (p = 0.002), PASAT2 (p < 0.001) and WLG (p = 0.01) than controls from the general population. Patients with clinically borderline scores of depression scored lower on SDMT (49.5 versus 57.1, p = 0.06) and PASAT3 (39.8 versus 47.1, p = 0.03). However, after adjustment for EDSS and time since disease onset, these differences were not statistically significant. Conclusion: Within two years after diagnosis, patients with MS had lower scores compared to healthy controls on timed tasks, suggesting cognitive slowing in patients with early MS. Cognitive impairment was associated with symptoms of depression, but this association could be explained by differences in disability.