Using the Symbol Digit Modalities Test in Clinic; Looking at Cognition Mood in MS

Background: Cognitive decline in multiple sclerosis is one of the most serious consequences of the disease.  Deficits in mental abilities coexist with physical disabilities and can have great impact.  Between forty to sixty-five percent of patients with MS may experience cognitive deficits.  While full neuropsychiatric assessment can be impractical, clinical tools to measure cognitive ability exist. 

Objectives: We propose that one such tool, the Symbol Digit Modalities Test (SDMT), which evaluates processing speed and working memory - two modalities disporportionately affected in multiple sclerosis, can be easily administered during a clinic visit, and can demonstrate our experience with the same in an observational study based in our Los Angeles County + University of Southern California Clinics.

Methods: The overarching goal of this project was to evaluate memory and concentration using the SDMT to determine if this is a reasonable tool to use in our clinic population, while looking at mood, satisfaction, and medications to see if they may have an effect on SDMT tests in multiple sclerosis patients over time so we can better understand and treat patients.  While conducting the SDMT tests, we also administered questioning about mood, satisfaction, symptoms, and medication use in our cohort study patients.  The SDMT was repeated on subsequent visits and used as a marker of cognitive impairment, decline, improvement, and/or stability over the course of 3 to 6 months.

Results: Nearly all of the 25 patients we recruited were able to complete the SDMT testing, and the majority of our patients were followed over time allowing us to conclude that this is a reasonable tool to employ in the clinic setting.  We also gathered information about mood, satisfaction, symptoms, and medication use that was reviewed to look for any trends or commonalities in performance on SDMT testing and to better understand individual patients care.

Conclusions: The SDMT test was deemed an easy to use tool in the clinic setting to evaluate cognitive function in patients with multiple sclerosis.  Still, the pathophysiology of cognitive problems in MS has proven difficult to unravel.  To date, our review of the literature has found that standard immunotherapies have not shown effect on cognition; nor have acetylcholine esterase inhibitors, amphetamines, and gingko.  We present evidence from our study that mood was closely linked to performance on the SDMT testing, and hypothesize that treatment may improve SDMT testing, or cognition, over time.  Antidepressants have been evaluated in a small number of MS trials, but not with this specific outcome measure in mind.  These latter points, combined with work done to evaluate imaging and immunologic components of depression, are of interest to the investigators for future study.