I just have one critical observation – not sure if the author removed the confounding bias introduced due to age-related change. Otherwise, insightful research.
Obstructive sleep apnea (OSA) is commonly associated with memory impairments. Although MRI studies have found volumetric differences in the hippocampus of people with OSA compared with controls, MRI lacks the spatial resolution to detect changes in the specific regions of the hippocampus that process different types of memory.
The present study performed histopathological investigations on autopsy brain tissue with OSA to examine whether the thickness and myelination of the hippocampus and entorhinal cortex (EC) vary as a function of OSA severity.
Increasing OSA severity was found to be related to cortical thinning in the molecular layer of the dentate gyrus. OSA severity was also related to decreased myelin in the deep layers but not the superficial layers of the EC.
Patients are known to have used continuous positive airway pressure (CPAP) treatment showed no significant reductions in cortical thickness when compared with controls, suggesting that CPAP had a protective effect.
However, CPAP did not protect against myelin loss. The regions of decreased cortical thickness and demyelination are locations of synaptic connections in both the polysynaptic (episodic and spatial) and direct (semantic) memory pathways and may underpin the impairments observed in episodic, semantic, and spatial memory in people with OSA.