Cognitive Impairment is Linked to Depression and Anxiety in Multiple Sclerosis

Neurologist Sarah Morrow of the University of Western Ontario in London shared her knowledge of cognitive, depression, and anxiety in MS at the CMSC Annual Meeting on Wednesday.ORLANDO, Fla. – Depression is well recognized as a common symptom in multiple sclerosis (MS), with a lifetime prevalence of nearly 50% in people with the disease. Sarah Morrow , MD, MS, FRCPC, Associate Professor of Neurology at the University of Western Ontario, discussed her research on the interplay between depression, anxiety, and cognition at the CMSC Annual Meeting on Wednesday, October 27. “In addition to the substantial impact on quality of life, depression is associated with suicide risk, which is seven times higher in persons with MS than in the non-MS population,” Dr. Morrow said. Suicide risk in people with MS is highest in young males in the first five years after diagnosis.

Depression can have similar symptoms as MS, she noted, including fatigue, cognitive complaints such as poor concentration and memory difficulties, and vegetative symptoms such as altered patterns of sleep and appetite. For people with MS, anxiety symptoms frequently go hand in hand with depression. Dr. Morrow cited data showing that among patients with MS who had severe depression, 78% suffered from moderate to severe anxiety. “These are really big issues in our clinics,” Dr. Morrow stated. “Along with suicidal ideation, we need to be aware of issues with substance abuse and somatic complaints that may be caused or exacerbated by depression and anxiety.”

Many studies in MS tend to place mood dysfunction and cognitive impairment into separate baskets, but Dr. Morrow has been interested in studying the interrelationships between these aspects of MS. Cognitive impairment can begin as early as the first demyelinating event and usually affects the domains of memory and information processing speed. Dr. Morrow’s research has suggested that depression can impact or worsen cognitive functioning in people with MS by affecting other domains like executive function and attention. “The capacity-reduction theory suggests that depression reduces one’s overall capacity to process information,” she said. “Patients who are depressed allocate more resources to processing negative information, leaving less resources available for other tasks.”

Depressive disorders may even lead people to believe they are experiencing MS-related cognitive impairment. Dr. Morrow cited data from a study of 108 patients with MS. Many (30 of 39) were able to accurately identify themselves as cognitively impaired. However, a large proportion (51 of 69) rated themselves as impaired even when they were not, based on cognitive test results. In this study anxiety was found to be a significant predictor of self‐rated cognitive impairment, more so than depression.

"Depression, anxiety, and cognitive impairment are all very prominent in persons with MS,” Dr. Morrow concluded. “Similarly, fatigue makes people feel like they cannot function well cognitively, so it's important to keep in mind that if you see someone who has a component of cognitive impairment, some of these other factors may be involved.”