Polysomnography, brain volumetry, and mismatch negativity as early biomarkers of amnestic mild cognitive impairment progression

Abstract Background Mild cognitive impairment (MCI) is a heterogenous disorder in which a proportion of patients follow stationary or regressive courses while others undergo clinical progression to dementia. Methods This study was conducted on 60 amnestic mild cognitive impairment (amMCI) and 20 healthy control subjects submitted to baseline Montreal Cognitive Assessment (MoCA) scale, one-night polysomnography (PSG), hippocampal/entorhinal cortex (HPC/ERC) MRI volumetry, and auditory mismatch negativity (MMN). Fifty-six amMCI subjects continued the study and underwent follow-up MoCA scale 1 year after their baseline evaluation, 17 showed amMCI progression (≥ 3 points decrease in MoCA scale), and 39 had stationary or regressive courses. Results Progressive amMCI patients showed reduced sleep efficiency and shortened rapid eye movement (REM) sleep in PSG, decreased HPC/ERC–MRI volumetry and reduced amplitudes with delayed latencies of the MMN evoked potentials. Conclusions PSG shortened REM sleep, MRI–HPC/ERC volumes reduction, and low amplitude delayed auditory MMN are valuable non-invasive screening predictors of amMCI progression