Abstract 2674: Brain White Matter Abnormalities Differ in Obstructive Sleep Apnea Patients with and without Depression
Obstructive sleep apnea (OSA) is frequently accompanied by depression; both syndromes place individuals at higher risk for cardiovascular disease (CVD), and both are associated with gray matter injury that may contribute to depression or CV consequences. The neural injury may be exacerbated by damage from projecting fibers; we hypothesized that pts with depression would differ in fiber injury.
Methods Using diffusion-weighted MRI images, we calculated fractional anisotropy (FA), a measure indicative of fiber tract myelination and density, in OSA pts and controls. OSA pts were divided into depressed (N = 9, age 49 ± 11 yrs) and non-depressed (N = 12, age 51 ± 6 yrs) groups by Beck Depression Inventory-II scores (>10 = depressed). After excluding 3 depressed controls, 38 remained (age 48 ± 7 yrs). We used ANCOVA to determine regions with abnormal FA in each OSA group relative to controls, with age and sex as covariates.
Results OSA pts showed lower FA values relative to controls, but locations differed between subgroups. Depressed pts showed abnormal fibers in the anterior cingulate and cingulum bundle, axons near the posterior right hippocampus, and the frontal cortex (p < 0.001; figure⇓). Non-depressed OSA pts showed abnormalities in the cerebellar cortex, left temporal lobe, prefrontal cortex, and head of caudate (p < 0.001).
Discussion Depression in OSA is associated with fiber abnormalities in axons serving affective sites. Non-depressed pts show injury primarily in fibers of motor regulation, including autonomic motor regulatory areas. Such damage may affect both autonomic motor output and affective influences on autonomic outflow, contributing independent risk factors for CVD.