Sleep depth and cognitive function in Parkinson's disease: An analysis using the Odd's Ratio Product (ORP)

Area of Science:

• Neurology
• Sleep Medicine
• Cognitive Neuroscience

Background:

• Obstructive sleep apnea (OSA) is associated with cognitive dysfunction in Parkinson's disease (PD) and the general population.
• Sleep depth, quantified by Odds Ratio Product (ORP), offers potential insights into the relationship between PD, OSA, and cognition.

Purpose of the Study:

• To characterize sleep depth using ORP metrics in individuals with PD and OSA.
• To examine the associations between sleep depth and cognitive function in these groups.

Main Methods:

• Analysis of polysomnography and Montreal Cognitive Assessment (MoCA) data from 217 PD patients and 633 controls.
• Categorization into four groups: PD+OSA+, PD+OSA-, PD-OSA+, PD-OSA-.
• Assessment of various ORP metrics (e.g., ORP_TRT, ORP_N2, ORP_REM, ORPdiff) and their association with MoCA scores using regression analyses.

Main Results:

• PD groups exhibited higher ORP_TRT compared to controls; PD+OSA+ showed higher ORP_TRT than PD-OSA+.
• Specific ORP metrics (ORP_N2, ORP_REM, ORP-9) were lowest in the PD-OSA- group.
• ORPdiff was associated with MoCA scores in the entire sample, with a significant interaction in PD patients, and inversely correlated with non-motor PD symptoms.

Conclusions:

• Both PD and OSA independently affect sleep depth, with PD having a more pronounced impact.
• Specific ORP measures correlate with cognitive function, particularly in PD.
• Non-restorative sleep (lower ORPdiff) is linked to cognitive function and non-motor symptoms in PD, suggesting ORP's utility in differentiating PD- and OSA-related sleep changes.