This 61-year-old right-handed man presented with a 3-year history of worsening memory and slowness in thinking. Working as an accountant, he first noticed his ability to process information quickly had diminished, particularly when performing calculations. Multitasking had also become more challenging. More recently, he became forgetful and more often relied on making notes, uncharacteristic for him. He reported he would eventually remember things, but usually needed a hint to do so. He did not experience any changes in language or visuospatial abilities. He denied depression, but acknowledged feeling tired most of the day, despite sleeping nine hours at night and napping for one hour on the weekends. He reported a 20-year history of polysomnogram (PSG)-confirmed obstructive sleep apnea (apnea-hypopnea index of 35, consistent with severe sleep apnea), but had not used a continuous positive airway pressure (CPAP) machine. His current medication regimen included aspirin, enalapril, and metformin. Other than obesity, his general physical examination was unremarkable.