关键词: 阿尔茨海默病; 轻度认知障碍; 海马; 记忆

Abstract:

Objective To determine which type of memory test can better predict hippocampus topography change underlying amnestic form of mild cognitive impairment(aMCI) conversion to Alzheimer's disease(AD) over a year period. Methods Three subtypes of patients with aMCI: 30 patients with predominant verbal memory impairment(verbal-aMCI), 28 with predominant visual memory impairment(visual-aMCI) and 44 with both verbal and visual memory-predominant impairment(both-aMCI), were enrolled. The level of hippocampal atrophy at baseline and a year later using visual 4-grade scale on magnetic resonance images(MRI) were analyzed. Patients were treated with either donepezil, rivastigmine or galantamine at a low dose. Results Data at baseline indicated that more patients(80%) with verbal-aMCI showed marked cortical thinning in the left hippocampus compared with visual-aMCI(43%). The cortical thinning areas of both-aMCI group overlapped those of verbal-aMCI but were more extensive and the proportion of patients with atrophic hippocampus got to 91 percent. After one year observation, the conversion rates of clinical dementia in the former subgroups(verbal-aMCI, visual-aMCI and both-aMCI) were 20.0%, 10.7% and 31.8%, respectively. More patients' initially diagnosed verbal-aMCI(50%) and both-aMCI(68.2%) were characterized by bilateral hippocampal atrophy or thinning aggravation, but only a small proportion(28.6%) of visual-aMCI patients indicated a mild bilateral hippocampal shrinking. Conclusion The verbal-aMCI and both-aMCI are more likely to be a precursor of AD than aMCI,and verbal memory test combined with hippocampal atrophy is more sensitive in predicting the aMCI conversion over a year period.

Key words: Alzheimer's disease; Mild cognitive impairment; Hippocampus; Memory