Regional Cerebral Blood Flow during Wakeful Rest in Older Subjects with Mild to Severe Obstructive Sleep Apnea.
Level 4 - case-series / case-control
Case-control neuroimaging study comparing OSA patients across severity tiers to healthy controls.
PubMed 25761981 · doi:10.5665/sleep.4986
What was done
Fifty untreated obstructive sleep apnea (OSA) patients aged 55 to 85 years (categorized into mild, moderate, and severe OSA) and 20 age-matched healthy controls underwent high-resolution 99mTc-HMPAO SPECT imaging during wakeful rest. Regional cerebral blood flow (rCBF) was assessed using statistical parametric mapping and correlated with clinical, respiratory, and polysomnographic sleep metrics.
What was found
No significant rCBF changes were observed in the mild or moderate OSA groups compared to controls. Participants with severe OSA showed reduced rCBF in the left parietal lobules, left precentral gyrus, bilateral postcentral gyri, and right precuneus. Lower rCBF in these areas plus bilateral frontal and left temporal cortices correlated with higher hypopnea counts, snoring, hypoxemia, and sleepiness. Higher apnea index, microarousal index, and body mass index correlated with increased rCBF in the basal ganglia, insula, and limbic system. The abstract does not report numerical perfusion rates, correlation coefficients, or p-values.
Why it matters
This demonstrates that severe OSA in older adults is associated with distinct regional hemodynamic abnormalities during wakefulness, featuring cortical hypoperfusion and subcortical hyperperfusion that may contribute to neurocognitive deficits and vascular dysregulation.
Limits
The study is limited by a modest sample size (70 participants total) and a cross-sectional design that cannot determine causality. It is restricted to older adults (55-85 years), limiting generalizability to younger demographics, and the abstract omits quantitative point estimates and confidence intervals.
Cited by
- supports A Montreal Neurological Institute study using SPECT imaging showed significant perfusion decreases in the parietal lobes of individuals with sleep apnea.