Contribution of Depression to Both Supervised and Unsupervised Tests of Processing Speed in Multiple Sclerosis

Background: Slowed information processing is commonly seen in individuals with MS. Cognitive rehabilitation via at-home digital monitoring and therapeutics, including tablet-, smartphone-, and computer-based games, may be beneficial. First, we must correlate these games with standard pen-and-paper evaluations and with other clinical measures, to highlight confounds and avenues for optimizing their development.

Objectives: 1) To compare gold-standard, supervised cognitive batteries with exploratory, unsupervised digital tools. 2) To examine and address potential confounding factors including emotional burden and disease severity, to more accurately capture desired outcome measure(s).

Methods: 50 participants with MS completed the Hospital Anxiety and Depression Scale (HADS) and were assessed with a Neurostatus Expanded Disability Status Scale (EDSS) exam: a standardized level of impairment due to MS. They completed supervised paper-and-pencil cognitive tests including SDMT, CVLT, and BVMT. Next they completed unsupervised tablet- and computer-based tests including a four-part MS Battery and Match, a test of executive function and processing speed, developed at UCSF. HADS scores, EDSS, and Disease Duration were correlated with performance on both supervised and unsupervised cognitive tests.

Results: Depression and anxiety were highly correlated intraindividually (Pearson r=.60, P<.00001). Depression was negatively correlated with performance on the SDMT (r=-.31, P=.03), the most widely used neuropsychological test of processing speed in MS. Match, an unsupervised, strong correlate of SDMT (r=0.70, P<.00001), was also significantly negatively correlated with depression (r=-.32, P=.03). The visual learning portion of the computer-based cognitive battery was also affected (r=-.074, P=.02). Disease duration, EDSS, and anxiety did not predict performance on processing speed (P>.05 for each), suggesting depression as a distinct process for this deficit.

Conclusions: Both supervised (SDMT) and unsupervised (Match) tests of processing speed are significantly impacted by depression. Tests of downstream cognitive processes, including visual memory in this instance, may be affected as well. The HADS can efficiently be administered in parallel with cognitive batteries on the same platforms (computer, tablet, smartphone). As digital cognitive evaluative tools are developed and implemented for at-home training and remote monitoring, depression scores must be captured and accounted for when analyzing cognitive performance outcomes.