Disturbed Sleep Can Impair Blood-Brain Barrier Through Oxidative Stress, Neuroinflammation: Study

Disturbed sleep can impair the integrity of blood-brain barrier through multiple mechanisms, including oxidative stress and neuroinflammation, according to a review of published studies.

The blood-brain barrier is highly selective and semi-permeable, separating blood from the brain's fluid. It protects the central nervous system from disease-causing agents and toxins and allows essential nutrients to pass through.

Researchers from the Shanghai Jiao Tong University said growing evidence shows that an injury to the blood-brain barrier is associated with cognitive impairment, including Alzheimer's disease, and conditions affecting the brain's blood vessels and white matter.

A blood-brain barrier injury can increase paracellular permeability or the movement of ions, water and small molecules through the intercellular spaces and impair metabolic clearance routes, they said.

The review, published in the journal LabMed Discovery, "summarises evidence that disturbed sleep impairs BBB (blood-brain barrier) integrity and discusses the underlying mechanisms".

The mechanisms include oxidative stress, neuroinflammation and gut microbiota dysbiosis -- an imbalance in the gut microbiome -- among others, it found.

Circadian disruption, involving a misalignment in sleep-wake cycles, is another mechanism through which disturbed sleep can impair the blood-brain barrier.

Among sleep disorders, obstructive sleep apnoea showed the strongest direct human evidence of injury to the blood-brain barrier.

The review also noted that a breakdown of the blood-brain barrier in the hippocampus, or the brain's memory region, may serve as an early marker of cognitive dysfunction.

The researchers said the marker is partly independent of classical amyloid-beta and tau pathology, according to which cognitive dysfunction is associated with clumping of amyloid-beta and tau proteins in the brain that causes cell death.

The review also evaluates candidate biomarkers, including dynamic contrast-enhanced MRI, and discusses current therapeutic strategies, with the most direct approach being treatment of the underlying sleep disorder, the researchers said.

They also identified key knowledge gaps, including the lack of validated blood-brain barrier biomarkers in sleep disorders and limited evidence for reversibility of injury after treatment.

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