BackgroundSleep difficulties are common in people with multiple sclerosis (MS), but whether associations between poor sleep quality and quality of life are independent of MS symptoms, obesity and other MS-related factors remains unclear.MethodsCross-sectional analyses of data from the Australian MS Longitudinal Study (n=1717). Sleep was assessed using the Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale and International Restless Legs Syndrome Study Group Rating Scale; health-related quality of life using the Assessment of Quality-of-Life 8-D.ResultsPoor sleep quality was common (67%), and more common than in community samples. Sleep measures clustered independently within MS symptoms. The clusters ‘fatigue and cognitive’, ‘feelings of anxiety and depression’, ‘pain and sensory’, were independently associated with poor sleep quality. Quality-of-Life utility scores were a clinically meaningful 0.19 units lower in those with poor sleep. Sleep quality, daytime sleepiness and restless leg syndrome were associated with reduced quality of life, independent of MS-related symptoms and body mass index.ConclusionPoor sleep quality is common in MS and was strongly associated with worse health-related quality of life, independent of other MS symptoms and did not cluster with other common MS symptoms. Improving sleep quality may substantially improve quality of life in people with MS.

Social-cognitive difficulties can negatively impact interpersonal communication, shared social experience, and meaningful relationships. This pilot investigation examined the relationship between social-cognitive functioning and inflammatory markers in people with multiple sclerosis (MS) and demographically-matched healthy individuals. Additionally, we compared the immune marker profile in serum and urine-matched samples. Social cognitive functioning was objectively assessed using The Awareness of Social Inference Test – Short (TASIT-S) and subjectively assessed using self-reports of abilities in emotion recognition, emotional empathy, and cognitive theory of mind. In people with MS and healthy individuals, there were moderate-to-large negative relationships between pro-inflammatory biomarkers (serum IL-1β, IL-17, TNF-α, IP-10, MIP-1α, and urine IP-10, MIP-1β) of the innate immune system and social-cognitive functioning. In MS, a higher serum concentration of the anti-inflammatory marker IL-1ra was associated with better social-cognitive functioning (i.e., self-reported emotional empathy and TASIT-S sarcasm detection performance). However, there were mixed findings for anti-inflammatory serum markers IL-4 and IL-10. Overall, our findings indicate a relationship between pro-inflammatory cytokines and social-cognitive abilities. Future studies may provide greater insight into biologically-derived inflammatory processes, sickness behaviour, and their connection with social cognition.

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