Association between sleep disorders and cognitive dysfunctions in non-demented patients with advanced Parkinson's disease

Effects of dopaminergic therapy on sleep quality in fluctuating Parkinson's disease patients

BACKGROUND

Sleep disorders negatively impact quality of life in Parkinson's disease (PD), yet the role of antiparkinsonian drugs on sleep quality is still unclear. We aimed to explore the correlation between sleep dysfunction and dopaminergic therapy in a large cohort of advanced PD patients.

METHODS

Patients consecutively evaluated for device-aided therapies eligibility were evaluated by means of the PD Sleep Scale (PDSS-2; score ≥ 18 indicates poor sleep quality), and the Epworth Sleepiness Scale (ESS score ≥ 10 indicates excessive daytime sleepiness-EDS). Binary logistic regression analysis, adjusting for age, sex, disease duration, motor impairment, and sleep drugs, was employed to evaluate the association between dopaminergic therapy and PDSS-2 and ESS scores. Analysis of covariance assessed differences in PDSS-2 and ESS scores between patients without DA, and between patients treated with low or high doses of DA (cut-off: DA-LEDD = 180 mg).

RESULTS

In a cohort of 281 patients, 66.2% reported poor sleep quality, and 34.5% reported EDS. DA treatment demonstrated twofold lower odds of reporting relevant sleep disturbances (OR 0.498; p = 0.035), while DA-LEDD, levodopa-LEDD, total LEDD, and extended-release levodopa were not associated with disturbed sleep. EDS was not influenced by dopaminergic therapy. Patients with DA intake reported significant lower PDSS-2 total score (p = 0.027) and "motor symptoms at night" domain score (p = 0.044). Patients with higher doses of DA showed lower PDSS-2 total score (p = 0.043).

CONCLUSION

Our study highlights the positive influence of DA add-on treatment on sleep quality in this group of advanced fluctuating PD patients.

Short sleep duration is associated with worse quality of life in Parkinson's disease: A multicenter cross-sectional study

OBJECTIVE

To characterize sleep duration and investigate its association with quality of life among Parkinson's Disease (PD) patients.

METHODS

In this multicenter cross-sectional study, 970 PD patients were divided into five groups based on self-reported sleep duration: <5, ≥5 to <6, ≥6 to <7, ≥7 to ≤8, and >8 h. The quality of life was evaluated using the 39-Item Parkinson's Disease Questionnaire (PDQ-39). Multivariable linear regression analysis, subgroup analysis, and mediation analysis were conducted to examine the association between sleep duration and quality of life.

RESULTS

In multivariable linear regression model, patients with sleep duration (<5 h) had significantly higher PDQ-39 scores (β = 8.132, 95 % CI: 3.99 to 12.266), especially in mobility, activities of daily living, emotional well-being, stigma, social support, cognition, communication, and bodily discomfort (p < 0.05). The association between sleep duration (<5 h) and worse quality of life was more pronounced in patients with higher HY stage, longer disease duration, and sleep disorders. Moreover, a significant indirect effect of sleep duration (<5 h) on quality of life was observed, with UPDRS I, UPDRS II, and UPDRS IV scores acting as mediators.

CONCLUSIONS

Short sleep duration (<5 h) is associated with worse quality of life among PD patients. This association was stronger among patients with advanced PD and sleep disorders, while non-motor symptoms and motor complications were identified as significant mediators in this association. These findings highlight the significance of adequate sleep duration and suitable interventions for sleep may help improve quality of life.

Neurological Insights into Sleep Disorders in Parkinson's Disease

Parkinson's disease (PD) is a common multidimensional neurological disorder characterized by motor and non-motor features and is more prevalent in the elderly. Sleep disorders and cognitive disturbances are also significant characteristics of PD. Sleep is an important physiological process for normal human cognition and physical functioning. Sleep deprivation negatively impacts human physical, mental, and behavioral functions. Sleep disturbances include problems falling asleep, disturbances occurring during sleep, abnormal movements during sleep, insufficient sleep, and excessive sleep. The most recognizable and known sleep disorders, such as rapid-eye-movement behavior disorder (RBD), insomnia, excessive daytime sleepiness (EDS), restless legs syndrome (RLS), sleep-related breathing disorders (SRBDs), and circadian-rhythm-related sleep-wake disorders (CRSWDs), have been associated with PD. RBD and associated emotional disorders are common non-motor symptoms of PD. In individuals, sleep disorders and cognitive impairment are important prognostic factors for predicting progressing neurodegeneration and developing dementia conditions in PD. Studies have focused on RBD and its associated neurological changes and functional deficits in PD patients. Other risks, such as cognitive decline, anxiety, and depression, are related to RBD. Sleep-disorder diagnosis is challenging, especially in identifying the essential factors that disturb the sleep-wake cycle and the co-existence of other concomitant sleep issues, motor symptoms, and breathing disorders. Focusing on sleep patterns and their disturbances, including genetic and other neurochemical changes, helps us to better understand the central causes of sleep alterations and cognitive functions in PD patients. Relations between α-synuclein aggregation in the brain and gender differences in sleep disorders have been reported. The existing correlation between sleep disorders and levels of α-synuclein in the cerebrospinal fluid indicates the risk of progression of synucleinopathies. Multidirectional approaches are required to correlate sleep disorders and neuropsychiatric symptoms and diagnose sensitive biomarkers for neurodegeneration. The evaluation of sleep pattern disturbances and cognitive impairment may aid in the development of novel and effective treatments for PD.