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

摘要：

目的 明确何种类型的记忆测试能更好地预测1年后遗忘型轻度认知障碍向阿尔茨海默病（Alzheimer’s disease，AD）转变相关的海马形态学改变。方法 用海马冠状位磁共振扫描T1像0～4分的视觉等级评分法，比较3组遗忘型轻度认知障碍患者的海马萎缩程度，分组为听觉记忆受损组（n =30）、视觉记忆受损组（n =28）、视觉与听觉记忆均受损组（n =44）。患者均接受了多奈哌齐、艾斯能或加兰他敏中的任一药物治疗。结果 基线资料显示听觉记忆受损组存在较高比例（80%）的海马萎缩，高于视觉记忆受损组海马萎缩的比例（43%），视觉与听觉记忆均受损组海马萎缩的比例达91%，且萎缩的皮层更广泛。1年后，听觉记忆受损组、视觉记忆受损组和视觉听觉记忆均受损组向临床痴呆的转化率分别为20.0%、10.7%和31.8%。有极高比例的听觉记忆受损患者（50%）和视觉听觉记忆均受损者（68.2%）出现双侧海马萎缩或萎缩程度较前加重，而仅有较少比例（28.6%）的视觉记忆受损患者出现双侧海马的轻度萎缩。结论 听觉记忆受损和视觉听觉记忆均受损的遗忘型轻度认知障碍患者更可能是AD的前期状态，听觉记忆测试较视觉记忆测试更能敏感预测1年后遗忘型轻度认知障碍患者海马萎缩程度

关键词: 阿尔茨海默病; 轻度认知障碍; 海马; 记忆