Actigraphically-defined sleep disturbance in Parkinson's disease is associated with differential aspects of cognitive functioning

The frequency of sleep disturbance and cognitive impairment in Parkinson's disease has led to the suggestion that these processes might share common neural circuitry. This study aimed to identify the relationships between measures of cognitive functioning and an objective measure of sleep disturbance. Ninety-five patients with idiopathic Parkinson's disease and 48 healthy controls underwent neurological and neuropsychological examination. They wore an actigraphy watch for 2 weeks, from which a measure of nocturnal sleep efficiency was calculated. Multiple regression models showed that working memory and verbal memory consolidation were significantly associated with sleep efficiency, as well as education and age. By contrast, verbal fluency and attentional set-shifting were not associated with sleep efficiency, after accounting for age and education. These findings reveal that nocturnal sleep disturbance in Parkinson's disease is associated with specific cognitive difficulties, rather than a global pattern of cognitive dysfunction. This may in part reflect common neural underpinnings.