Correlation of the symbol digit modalities test with the quality of life and depression in Japanese patients with multiple sclerosis

Background : This study aimed to evaluate the association between cognitive impairment and health-related quality of life (HRQOL), fatigue, and depression in Japanese patients with multiple sclerosis (MS). Methods : The Brief International Cognitive Assessment for MS (BICAMS) was performed in 184 Japanese patients with MS. The Functional Assessment of MS (FAMS), Fatigue Severity Scale (FSS), and Beck Depression Inventory-Second Edition (BDI-II) were used to evaluate HRQOL, fatigue, and depression, respectively. Results : Multiple linear regression analysis demonstrated positive correlations of the Symbol Digit Modalities Test (SDMT) with the scores on the FAMS subscales of mobility, symptoms, emotional well-being, and additional concerns and with the total FAMS score even after controlling for the Expanded Disability Status Scale score, age at examination, and duration of education. The SDMT score in the BICAMS battery had negative correlations with the BDI-II score, as revealed by multiple linear regression analysis. None of the three tests in the BICAMS had any correlation with the FSS score. Conclusion : The SDMT has a significant relationship with HRQOL and depression in Japanese patients with MS.