In patients with multiple sclerosis (MS), psychiatric comorbidities may be common and are associated with an increased severity of subsequent neurologic disability, according to results from a recent study published in Neurology.
“Psychiatric comorbidities were common in our incident MS cohort. Overall, more than one-third of the 2,312 MS cases were found to have a mood or anxiety disorder. Presence of these comorbid conditions was associated with significantly higher subsequent disability over an average of 10 years of follow-up,” wrote these authors, led by Kyla A. McKay, PhD, Department of Medicine, Division of Neurology and Centre for Brain Health, University of British Columbia, Vancouver, Canada.
In this retrospective study, Dr. McKay and fellow researchers assessed the association between psychiatric comorbidity and MS disability progression. They used clinical and population-based health administrative databases from British Columbia and Nova Scotia, Canada, to identify patients with MS who had depression, anxiety, or bipolar disorder.
In all, they identified 2,312 patients with adult-onset MS (average age at onset: 36.9 years), of whom 35.8% had a mood or anxiety disorder, and followed them for a mean of 10.5 years. Most of the subjects were women (75.7%), and most had a relapsing-onset disease course (92.3%). Although most mood or anxiety disorders in these subjects began after the onset of MS, a full 43.5% began before the disease. Depression was the most common, affecting 37.0%, followed by anxiety in 22.1% and bipolar disorder in 5.1%.
After adjusting for disease duration and course, age, sex, socioeconomic status, physical comorbidity count, and disease-modifying therapy exposure, researchers found that the presence of a mood or anxiety disorder was associated with a higher Expanded Disability Status Scale (EDSS) score (ß coefficient: 0.28; P=0.0002). These associations were statistically significant in women (ß coefficient: 0.31, P=0.0004), but not men (ß coefficient 0.22; P=0.17).
Depression was the only condition that was significantly associated with a higher EDSS score in both unadjusted and adjusted analyses.
“MS disease progression is highly variable, and these results suggest that psychiatric comorbidities may explain some of the heterogeneity between individuals. The importance of recognizing psychiatric comorbidities in persons with MS and optimizing their treatment is clear, both from the perspective of improved quality of life and disability reduction,” concluded Dr. McKay and fellow researchers.
This study was supported by the Canadian Institutes of Health Research, the Rx & D Health Research Foundation, a Don Paty Career Development award from the Multiple Sclerosis Society of Canada, a Manitoba Research Chair from Research Manitoba, and the Waugh Family Chair in Multiple Sclerosis. Dr. McKay receives research funding from the Canadian Institute of Health Research.