Physical and mental comorbidities that affect treatment compliance and quality of life are common in patients with multiple sclerosis and are associated with adverse outcomes. The link between psychological disorders, such as depression and anxiety, and physical conditions, including chronic fatigue and chronic pain, is problematic because so many of the symptoms overlap.

“Fatigue is a leading cause of diminished quality of life among individuals with MS, and is often considered to be the single most debilitating symptom of the disease. Fatigue also imposes significant socioeconomic consequences, including loss of work hours and loss of employment,” said Tiffany Braley, MD, assistant professor of neurology at the University of Michigan Multiple Sclerosis Center and Sleep Disorders Center. “Similarly, depression is another complex comorbidity in MS that may have multiple causes, including brain changes from the disease process itself, difficulty in coping with the stress of having MS, medication effects, and contributions from other comorbid symptoms or conditions.”

A review published in Sleep Medicine estimated the prevalence of referral for fatigue among MS patients to be 64%, while sleep disorders ranged from 36–50%, and restless legs syndrome in ranged from 15.5% to nearly 28%.1

Additionally, a small study of 137 people with relapsing remitting MS published in 2014 found that 45.3% were experiencing sleep problems, 21.9% had depressive symptoms, and 19.7% had symptoms of anxiety.2

Both studies point to the difficulties of determining the prevalence of this cluster of comorbidities with the lack of a standard method of investigating and assessing these conditions and the use of a variety of data sources.

This article originally appeared on Neurology Advisor