Anxiety and depression are associated with lower cognitive function in patients with multiple sclerosis (MS), with a similar pattern observed among individuals with other immune-mediated inflammatory diseases (IMIDs), including irritable bowel disease and rheumatoid arthritis, as well as in those with no IMID. The current longitudinal study,1 which enrolled 4 cohorts of participants from Manitoba, Canada,2 was designed to explore the effects of comorbid anxiety and depression among individuals with an IMID. Findings from the study were published in Neurology.
A total of 964 patients (255 of whom had MS, 247 of whom had irritable bowel disease, 154 of whom had rheumatoid arthritis, and 308 of whom had anxiety/depression without any IMID) completed the following components: a structured psychiatric interview, the Hospital Anxiety and Depression Scale, and cognitive testing, including the Symbol Digit Modalities Test, the California Verbal Learning Test, and the Letter Number Sequencing Test. All the test scores were converted to age-adjusted, sex-adjusted, and education-adjusted z scores. The investigators assessed the associations of anxiety and depression with the cognitive z scores via the use of multivariate linear models.
Higher rates of impairment were displayed among all 4 cohorts (ie, z scores ≤−1.5) in the domains of processing speed, verbal learning, and delayed recall memory relative to the norms of the general population. Higher levels of anxiety symptoms were associated with significantly reduced processing speed (P <.0001), reduced verbal learning (P =.0077), and lower working memory performance (P <.001). Moreover, higher levels of depression symptoms were associated with significantly reduced processing speed (P <.035). These associations did not vary across the 4 different cohorts.
The investigators concluded that the management of symptoms of anxiety and depression in patients with MS, as well as in those with other IMIDs, is key to mitigating their effect on cognition and functioning. Future studies that use more complex cognitive tasks may help detect differences between individuals with MS and other IMIDs, including rheumatoid arthritis and irritable bowel disease, possibly revealing variances in the effects of comorbid anxiety and depression on cognitive function among individuals with these conditions.
1. Whitehouse CE, Fisk JD, Bernstein CN, et al. Comorbid anxiety, depression, and cognition in MS and other immune-mediated disorders [published online January 11, 2019]. Neurology. doi: 10.1212/WNL.0000000000006854
2. Marrie RA, Graff LA, Walker JR, et al. Effects of psychiatric comorbidity in immune-mediated inflammatory disease: protocol for a prospective study. JMIR Res Protoc. 2018;7:e15.