The effects of sleep dysfunction on cognition, affect, and quality of life in individuals with cerebellar ataxia.

STUDY OBJECTIVE Cerebellar ataxia comprises a group of debilitating diseases that are the result of progressive cerebellar degeneration. Recent studies suggest that, like other neurodegenerative diseases, sleep impairments are common in cerebellar ataxia. In light of the role of sleep in mood regulation and cognition, we sought to assess interactions between sleep, cognition, and affect in individuals with cerebellar ataxia. METHODS A survey of 176 individuals with cerebellar ataxia was conducted. The battery of instruments included a modified International Cooperative Ataxia Rating Scale, Pittsburgh Sleep Quality Index, Restless Leg Syndrome Questionnaire, REM Behavior Disorder Questionnaire, Beck Depression Inventory, Epworth Sleepiness Scale, and a Composite Cognitive Questionnaire. RESULTS Fifty-one percent of individuals indicated significant sleep disturbances on the Pittsburgh Sleep Quality Index, 73% of participants had two or more symptoms of restless leg syndrome, and 88% had two or more symptoms of REM behavior disorder. Ataxia severity, based on the modified International Cooperative Ataxia Rating Scale, predicted scores on the Pittsburgh Sleep Quality Index, the Epworth Sleepiness Scale and REM Behavior Disorder Questionnaire. Median split analyses revealed that cognitive function appeared to be reduced and depressive symptoms were greater for those individuals with poor subjective sleep quality and severe RLS. Importantly, sleep appears to play a mediatory role between disease severity and depressive symptoms. CONCLUSIONS These results suggest that disturbed sleep may have detrimental effects on cognition and affect in individuals with cerebellar ataxia. While objective measures are needed, such results suggest that treating sleep deficits in these individuals may improve cognitive and mental health as well as overall quality of life.