The link between depression and performance on the Symbol Digit Modalities Test: Mechanisms and clinical significance

Mult Scler. 2019 Jan;25(1):118-121. doi: 10.1177/1352458518770086. Epub 2018 Apr 12.

Abstract

Objective: To determine the mechanism and clinical significance of depression-related differences in performance on the Symbol Digit Modalities Test (SDMT).

Methods: The influence of depression on two versions of a computerized SDMT (i.e. fixed versus variable code) was assessed. Both versions involve processing speed, but the fixed c-SDMT also encompasses incidental visual memory.

Results: Depression was associated with a 19.06% slowing on the variable ( p = 0.002) and an 8.10% slowing on the fixed ( p = 0.219) c-SDMT.

Conclusion: Depression-associated differences in performance on the SDMT appear linked more to a reduction in processing speed than a decline in incidental visual memory and exceed the 10% threshold considered clinically significant.

Keywords: Multiple sclerosis; cognition; depression.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Cognitive Dysfunction / complications
  • Cognitive Dysfunction / physiopathology*
  • Depression / etiology
  • Depression / physiopathology*
  • Depressive Disorder / etiology
  • Depressive Disorder / physiopathology*
  • Female
  • Humans
  • Male
  • Memory / physiology
  • Middle Aged
  • Multiple Sclerosis / complications
  • Multiple Sclerosis / physiopathology*
  • Neuropsychological Tests
  • Pattern Recognition, Visual / physiology
  • Psychomotor Performance / physiology*