Relationship between cognitive disturbances and sleep disorders in multiple sclerosis is modulated by psychiatric symptoms

Background: Multiple sclerosis (MS) patients with cognitive impairment (CI) frequently suffer from sleep disturbances and emotional symptoms. The aim of this study was to investigate the relationship between CI and sleep disturbances and the role of anxiety and depression on this relationship in MS patients.

Methods: Prospective cross-sectional study including 80 MS patients that underwent neurologic, cognitive, psychiatric assessment, and polysomnographic registration. Partial correlations analysis adjusted by demographic and clinical variables were used to investigate associations between cognitive and sleep measures. Moderator role effect of psychiatric symptoms was also explored with linear models.

Results: Thirty-six MS patients had CI. In all patients, worse performances at global, memory and attention cognitive domains were correlated with reduced sleep efficacy and longer periods of nocturnal wake (NW), while poor attention performances were associated with reduced REM-sleep (r = 0.26, p = 0.022). Memory performances were also negatively correlated with anxiety (r = -0.27, p = 0.015). The relationship between NW and memory performances was moderated by trait anxiety (p < 0.001).

Conclusions: Our findings suggest that low sleep efficiency, NW, and reduced REM-sleep might affect cognitive abilities in MS. Higher trait anxiety appeared to impact on the relationship between increased NW and poor memory performances. Treatment of sleep and psychiatric disturbances may contribute to mitigating cognitive disorders in MS.