Reduced cerebral blood flow in obstructive sleep apnea: A meta-analysis of SPECT and MRI studies.

PURPOSE: Obstructive sleep apnea (OSA) is associated with increased risk of neurovascular and neurodegenerative disorders. However, cerebral blood flow (CBF) abnormalities in OSA remains unclear due to mixed findings across studies. METHOD: We conducted a meta-analysis and activation likelihood estimation (ALE) analyses of neuroimaging data to clarify the nature and extent of CBF changes in patients with OSA.

RESULTS

Among MRI studies employing arterial spin labelling (ASL) (k = 6), whole-brain CBF was significantly reduced in OSA patients compared to controls (SMD=-0.36, Z=-3.22, p=.001; CI: − 0.58 to − 0.14). Notably, this effect was not observed in non-ASL MRI studies (k = 4) (SMD=0.06, Z=0.27, p=.79; CI: − 0.35 to 0.46). ALE analyses revealed consistent hypoperfusion in the left parietal lobe across SPECT studies and in the left caudate, bilateral anterior cingulate cortex, and right medial frontal gyrus across MRI studies.

CONCLUSION

Our findings suggest that whole-brain CBF is modestly reduced in OSA, particularly when measured using ASL MRI. Regional hypoperfusion is consistently observed in fronto-striatal and parietal regions, though convergence is modality-specific. Variability in imaging techniques may account for discrepancies in the literature. Large-scale studies (n ≥ 140 per group) are warranted to investigate the potential cause(s) of CBF abnormalities in OSA.