Background: Anxiety, which is very prevalent in multiple sclerosis (MS) but understudied, has been shown to negatively affect cognition in many different populations. Slowed information processing speed underlies most cognitive impairments in MS, including verbal learning. The aim of this study was to look at how anxiety influences cognition-specifically processing speed and verbal learning-in MS.
Methods: Eligibility criteria were adults (≥18 years) who had a diagnosis of clinically definite MS and had participated in neuropsychological research projects. A retrospective medical record review was conducted on the neuropsychological testing data. Two hierarchical multiple regressions were conducted to determine the unique contributions of processing speed and anxiety on verbal learning in MS, after adjusting for demographic and disability variables. Two separate mediation analyses were conducted to determine the relationship between processing speed, verbal learning, and anxiety.
Results: Participants (N = 141) ranged in age from 18-91 years. Based on the multiple regression analyses, processing speed (β = 0.55, ΔR 2 = 0.27, P < .001) and anxiety (β = -0.34, ΔR 2 = 0.11, P < .001) were uniquely significant predictors of verbal learning. Based on the mediation analyses, there was a significant indirect effect of anxiety on verbal learning through processing speed (ab = -0.31, 95% CI = -0.60 to -0.09). There was also a significant indirect effect of processing speed on verbal learning through anxiety (ab = -0.05, 95% CI = 0.01 to 0.12).
Conclusions: Results suggest a bidirectional relationship of anxiety and processing speed on verbal learning in MS. Anxiety has a significant effect on cognition and should not be overlooked. Interventions targeting anxiety may improve cognition in MS.
Keywords: Anxiety; Cognition; Multiple sclerosis (MS); Processing speed; Verbal learning.