Plasma homocysteine in obstructive sleep apnoea

Area of Science:

• Cardiovascular Physiology
• Sleep Medicine
• Biochemistry

Background:

• Obstructive sleep apnea (OSA) is linked to cardiovascular abnormalities.
• The role of homocysteine as a mediator in this association is not fully understood.
• Hypotheses suggest elevated homocysteine in OSA patients, potentially worsening during sleep and improving with treatment.

Purpose of the Study:

• To investigate the relationship between obstructive sleep apnea (OSA) and plasma homocysteine levels.
• To determine if homocysteine levels change during sleep in OSA patients.
• To assess the effect of continuous positive airway pressure (CPAP) treatment on homocysteine.

Main Methods:

• Study A: Measured homocysteine in 22 OSA patients and 20 controls at three time points: before sleep, after 5 hours of untreated OSA, and post-CPAP treatment.
• Study B: Investigated diurnal variation with a full-night protocol in 10 OSA patients and 12 controls, measuring homocysteine before sleep, morning, and noon.
• Study C: Assessed the impact of disturbed sleep on homocysteine in healthy subjects.

Main Results:

• Homocysteine levels were similar between OSA patients and controls at all measured time points.
• A significant overnight decline in homocysteine was observed in both OSA patients and controls.
• This overnight decline was reversed by noon, indicating a diurnal pattern. Disturbed sleep did not affect homocysteine levels.

Conclusions:

• Plasma homocysteine exhibits significant diurnal variation, being lower in the morning post-waking.
• Obstructive sleep apnea (OSA) does not appear to cause acute or chronic changes in homocysteine levels.
• Disturbed sleep, independent of OSA, does not elicit changes in homocysteine.