ABSTRACT

Normal aging, mild cognitive impairment, and Alzheimer’s disease (AD) fall along a continuous spectrumof cognitive aging. Recently, there has been a strong recommendation to recognize preclinical stages ofMCI. Many studies that focused on this “between normal and MCI” status used various terminologiesindicating earlier stages of MCI, such as subjective memory impairment (SMI), subjective cognitiveimpairment (SCI), subjective cognitive decline (SCD), or pre-mild cognitive impairment (pre-MCI). Thereis no established common concept for preclinical stages of MCI yet. Different measurement andinclusion/exclusion criteria have been applied in many studies. In this paper, research criteria guidelines forthose terms denoting preclinical stage of MCI were briefly introduced. It is expected that one of thoseterms will provide potential usefulness for identifying preclinical MCI and clinical trials recruitment.