In obstructive sleep apnea (OSA), the hippocampus shows lateralized and sex-specific, OSA-related regional volume differences, which may contribute to sex-related expression of symptoms in the sleep disorder, according to a recent study. High-resolution T1-weighted images were collected from 66 newly-diagnosed, untreated OSA (mean age ± SD: 46.3 ± 8.8 years; 50 male) and 59 healthy age-matched control (46.8 ± 9.0 years; 38 male) participants. Researchers added age-matched controls with T1-weighted scans from 2 datasets (IXI, OASIS-MRI), for 979 controls total (426 male/46.5 ± 9.9 years). They found:
- In OSA relative to controls, the hippocampus showed small areas larger volume bilaterally in cornu ammonis (CA)1 (surface displacement ≤0.56 mm), subiculum, and uncus, and smaller volume in right posterior CA3/dentate (≥ − 0.23 mm).
- OSA vs control males showed higher bilateral volume (≤0.61 mm) throughout CA1 and subiculum, extending to head and tail, with greater right-sided increases; lower bilateral volumes (≥ − 0.45 mm) appeared in mid- and posterior-CA3/dentate.
- OSA vs control females showed only right-sided effects, with increased CA1 and subiculum/uncus volumes (≤0.67 mm), and decreased posterior CA3/dentate volumes (≥ − 0.52 mm).
- Unlike males, OSA females showed volume decreases in the right hippocampus head and tail.
Macey PM, Prasad JP, Ogren JA, et al. Sex-specific hippocampus volume changes in obstructive sleep apnea. [Published online ahead of print July 27, 2018]. Neuroimage Clin. doi:10.1016/j.nicl.2018.07.027.
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