The HC were volunteers and recruited through public advertisements at memory clinics, at local associations for elders, or through an online recruitment site. The inclusion criteria were (1) between 50 and 90 years old, (2) MMSE score >26, (3) ACE > 85, (4) normal neurological and clinical examination, (5) normal or age-related brain atrophy measured on a computed tomography scan, and (6) normal routine blood tests. The exclusion criteria were (1) an inability to participate (including impaired vision or hearing), (2) cognitive symptoms including memory complaints, (3) major neurological, psychiatric, or other severe diseases, which could cause cognitive impairments including major depression or a geriatric depression scale score >7, (4) pregnancy, (5) had undergone general anesthesia, (6) received electroconvulsive therapy in the last 3 months, (7) use of sedatives, or (8) past or current addiction to alcohol or medications.
