Mild cognitive impairment in the elderly

Abstract

The present review on mild cognitive impairment (MCI) concerns preclinical Alzheimer's disease (no cognitive impairment but neuropathological changes typical for Alzheimer's disease), subjective cognitive/memory complaints with and without verified neuropsychological deficit, and the validity of amnestic MCI. The following were shown to be predictors of Alzheimer's disease: measures of episodic memory; presence of the apolipoprotein E e4 allele; reduced cerebral temporo-parietal glucose metabolism and blood flow; neuronal loss in the entorhinal cortex, and in layer II and CA1 of the hippocampus; brain activation of the hippocampus through cognitive stress tests (as measured using structural and functional magnetic resonance imaging); and purely subjective cognitive impairment and features of age-associated cognitive decline. Furthermore, the distinction of MCI from both healthy and demented status, and the role of activities of daily living in MCI are emphasized. Early predictors and three stages (MCI spectrum disorder) in the development of Alzheimer's disease are discussed: asymptomatic Alzheimer's disease (including preclinical Alzheimer's disease), purely subjective cognitive complaints, and objective evidence of MCI.