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.

The Relationships Between Poor Sleep Efficiency and Mild Cognitive Impairment in Parkinson Disease.

BACKGROUND: Mild cognitive impairment (MCI) and sleep disturbances are common features in Parkinson disease (PD). This study sought to investigate whether patients with MCI in PD (PD-MCI) have more pronounced sleep disturbance compared to those without PD-MCI and whether phenotypic presentations differ according to the PD-MCI subtypes. METHODS: A total of 95 patients with idiopathic PD (53 meeting criteria for PD-MCI and 42 who were not cognitively impaired) and 22 controls underwent neurological and neuropsychological examination. They wore actigraphy watches for 2 weeks, from which measures of nocturnal sleep efficiency were calculated. RESULTS: Patients with PD-MCI has significantly poorer sleep efficiency compared to those without PD-MCI. This effect was particularly apparent in those with multiple-domain PD-MCI, compared to those with single-domain PD-MCI. Furthermore, patients in the PD-MCI group had significantly more nontremor features. CONCLUSIONS: These data suggest that PD-MCI is associated with greater sleep disturbance and nontremor features of PD. This is further evidence for the potential role that sleep disturbance plays in the heterogeneity of PD.

Unawareness of motor phenoconversion in Huntington disease.

OBJECTIVE: To determine whether Huntington disease (HD) mutation carriers have motor symptoms (complaints) when definite motor onset (motor phenoconversion) is diagnosed and document differences between the groups with and without unawareness of motor signs. METHODS: We analyzed data from 550 HD mutation carriers participating in the multicenter PREDICT-HD Study followed through the HD prodrome. Data analysis included demographics, the Unified Huntington's Disease Rating Scale (UHDRS) and the Participant HD History of symptoms, self-report of progression, and cognitive, behavioral, and imaging measures. Unawareness was identified when no motor symptoms were self-reported but when definite motor HD was diagnosed. RESULTS: Of 38 (6.91%) with onset of motor HD, almost half (18/38 = 47.36%) had no motor symptoms despite signs of disease on the UHDRS motor rating and consistent with unawareness. A group with motor symptoms and signs was similar on a range of measures to the unaware group. Those with unawareness of HD signs reported less depression. Patients with symptoms had more striatal atrophy on imaging measures. CONCLUSIONS: Only half of the patients with newly diagnosed motor HD had motor symptoms. Unaware patients were less likely to be depressed. Self-report of symptoms may be inaccurate in HD at the earliest stage.

Sleep disturbances in Parkinson disease and their potential role in heterogeneity.

Parkinson disease (PD) is commonly conceptualized as a movement disorder. Most previous attempts to define the heterogeneity of the condition have used prospective methods based on arbitrary features such as motor symptoms or age of disease onset. However, nonmotor symptoms including neuropsychological, neuropsychiatric, and behavioral impairments have received less attention. Sleep disturbances are extremely common in PD and appear to be associated with cognitive and psychiatric problems. Recent research has begun to elucidate the links between these variables, but the origin and extent of these relationships are not clearly understood. This review outlines the importance of sleep for healthy cognition and mood, highlighting the possible implications that disturbed sleep may have with regard to patients with PD. It also emphasizes the need for further studies that explore the heterogeneity of all disease features in PD.