Quality of Life, Self-Reported Cognitive Difficulties, and Performance-Based Cognitive Problems in Multiple Sclerosis: What's Sleep Got to Do With It?

OBJECTIVE

Examine group differences between people with multiple sclerosis (PwMS) with poor and adequate sleep quality on cognition (performance-based and self-reported difficulties) and examine the contribution of sleep quality on quality of life (QoL).

METHOD: Cross-sectional study of 97 PwMS. Two groups were created from a sleep quality composite: poor (n = 22) and adequate (n = 72) sleep quality. Seven domains from the Functional Assessment of Multiple Sclerosis (FAMS) assessed quality of life. A dichotomous (yes/no) item on the Sleep Habits Questionnaire assessed self-reported cognitive difficulties. Performance-based cognition was measured with a composite of mean neuropsychological performance and 2 intraindividual variability (IIV) indices. Two mulitavariate analyses of variance examined group differences on cognition and QoL. A chi-square test compared the proportion of PwMS with poor versus adequate sleep quality who self-reported cognitive difficulties. Follow-up hierarchical linear regressions were conducted to account for disease progression, fatigue, and depression.

RESULTS

PwMS with poor and adequate sleep quality did not significantly differ in terms of performance-based cognitive functioning. A significantly greater proportion of PwMS with poor sleep quality reported that sleep patterns affected their cognitive abilities (86.36%) compared to those with adequate sleep quality (40.28%), χ2(1, N = 94) = 14.32, p < .001, φ = -.39. After accounting for disease progression, depression, and fatigue, sleep quality significantly predicted Symptoms QoL, R2 =.04, ΔF(1,88) = 4.72, p = .03, and Fatigue QoL, R2 = .05, ΔF(1,89) = 5.64, p = .02.

CONCLUSIONS

Poor sleep quality was not associated with performance-based cognitive functioning but was associated with greater self-reported cognitive difficulties. After accounting for disease progression, depression, and fatigue, poor sleep quality was significantly predictive of both Symptoms and Fatigue QoL.