How were sleep apnoea measures linked to brain structure in adults at risk for dementia?

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The study investigated associations between obstructive sleep apnoea (OSA) and cortical thickness in adults with subjective and objective cognitive difficulties, considered at risk for dementia. It included 83 middle-aged to older adults aged 51–88, who underwent neuropsychological testing, polysomnography to assess OSA, and a structural magnetic resonance imaging brain scan.

Researchers used principal components analysis on the OSA measures. They compared cortical thickness and subcortical volumes with the extracted components of oxygen desaturation and sleep disturbance. Oxygen desaturation was significantly associated with reduced cortical thickness in both temporal lobes (left: r=-0.44, p<0.001; right: r=-0.39, p=0.003).

In contrast, sleep disturbance was associated with increased thickness in the right postcentral gyrus (r=0.48, p<0.001), pericalcarine region (r=0.50, p=0.005), and pars opercularis (r=0.46, p=0.009), as well as increased volume of the hippocampus and amygdala.

Reduced thickness in both temporal regions was associated with reduced verbal encoding (r=0.28, p=0.010). Given the sample’s clinical significance for dementia prevention, the authors suggested that these grey matter changes reveal how OSA might contribute to neurodegenerative processes in older adults.