Lack of tissue oxygenation associated with episodes of upper airway obstruction in patients with obstructive sleep apnea syndrome (OSAS) may increase the levels of alpha-synuclein in the blood and may contribute to the development of Parkinson’s disease, a study says.

The study, “Plasma ??synuclein levels are increased in patients with obstructive sleep apnea syndrome,” was published in the Annals of Clinical and Translational Neurology.

Parkinson’s disease mainly results from the gradual loss of dopaminergic neurons in the substantia nigra, a region of the brain responsible for controlling movement. The disease also seems to be associated with overproduction of the protein alpha-synuclein in nerve cells of the brain. When this protein clumps together, it gives rise to small toxic deposits inside brain cells, called Lewy bodies, inflicting damage and eventually killing them.

Of note, alpha-synuclein phosphorylation — a chemical modification in which a phosphate group is added to the protein — is known to occur in Parkinson’s disease, and is thought to be a critical step in disease progression as it enhances alpha-synuclein’s toxicity, possibly by increasing the formation of alpha synuclein aggregates.

“Recent studies found that [obstructive sleep apnea] was a risk factor for PD [Parkinson’s disease] onset, and hypoxia [lack of oxygen] may have contributed to it. [In addition,] previous studies both in vitro and in vivo revealed that hypoxia is able to induce overexpression of alpha?synuclein (…). However, the detail mechanism remains to be further investigated,” the researchers wrote.

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