Neural mechanisms linking sleep disturbances to motor and cognitive impairments in Parkinson's disease: Evidence from resting-state and task-based fNIRS.

BACKGROUND

Sleep disturbances are common non-motor symptoms of Parkinson's disease (PD), negatively affecting daily functioning, exacerbating motor symptoms, and contributing to cognitive impairment. However, the underlying neurobiological mechanisms are not well understood. This study utilized resting-state and task-based functional near-infrared spectroscopy (fNIRS) to explore how sleep disturbances affect brain function in PD patients at the neural level.

METHODS

Sixty PD patients were recruited, including 30 with sleep disturbances and 30 without. Resting-state fNIRS and clinical assessments were used to analyze spontaneous brain activity and functional connectivity. We also examined the mediating role of brain activity in the relationship between sleep disturbances and motor symptoms. The verbal fluency test (VFT) was employed to investigate changes in brain mechanisms related to executive function in patients with sleep disturbances.

RESULTS

Resting-state analysis revealed significantly increased fractional amplitude of low-frequency fluctuations (fALFF) in the medial prefrontal cortex (mPFC) in PD patients with sleep disturbances. fALFF values were negatively correlated with sleep quality and positively with motor symptom severity. Mediation analysis indicated that spontaneous neural activity in the mPFC partially mediated the relationship between sleep disturbances and motor symptoms. Task-based analysis showed reduced activation in the mPFC and orbitofrontal cortex (OFC) during the VFT in patients with sleep disturbances, indicating impaired executive function.

CONCLUSION

Sleep disturbances in PD could be associated with exacerbated motor symptoms and may impair executive function by affecting spontaneous and task-related neural activity in the mPFC. These findings highlight mPFC dysfunction as a potential biomarker for targeted therapies.