Bergem A L, Engedal K, Kringlen E
Department of Psychiatry, Vinderen, University of Oslo, Norway.
Arch Gen Psychiatry. 1997 Mar;54(3):264-70. doi: 10.1001/archpsyc.1997.01830150090013.
This study compares the relative importance of heredity and environment in the development of Alzheimer disease and vascular dementia. The relationship between apolipoprotein E and dementia is also tested.
A total of 23,000 cognitively impaired subjects from Norwegian institutions for the elderly were identified, and their files were checked against the records of 26,000 twin pairs from the Norwegian Twin Register. A sample of 72 twin pairs was selected and thoroughly investigated clinically. The mean age of the sample was 80 years.
The pairwise concordance rate for Alzheimer disease was 78% (7/9) among monozygotic and 39% (9/23) among dizygotic twin pairs. The probandwise concordance rate was 83% (10/12) among monozygotic and 46% (12/26) among dizygotic twin pairs. There was no significant difference in the rate of apolipoprotein E epsilon 4 allele between twin pairs concordant and discordant for Alzheimer disease. By using tetrachoric correlations, the estimated heritability was approximately 0.6. Environmental factors shared by cotwins seemed to explain most of the remaining variance. In vascular dementia, there was no significant difference in pairwise concordance rates among monozygotic (1/6 [17%]) and dizygotic (4/16 [25%]) twin pairs or in probandwise concordance rates among monozygotic (2/7 [29%]) and dizygotic (5/17 [29%]) twin pairs.
Heredity is the major causal factor in late onset Alzheimer disease, whereas environmental factors dominate in vascular dementia.
本研究比较遗传因素和环境因素在阿尔茨海默病及血管性痴呆发病过程中的相对重要性。同时也检测了载脂蛋白E与痴呆之间的关系。
从挪威老年机构中识别出23000名认知受损受试者，并将他们的档案与挪威双胞胎登记处的26000对双胞胎记录进行比对。选取72对双胞胎进行临床详细调查。样本的平均年龄为80岁。
在阿尔茨海默病方面，单卵双胞胎的成对一致性率为78%（7/9），双卵双胞胎为39%（9/23）。先证者一致性率在单卵双胞胎中为83%（10/12），双卵双胞胎中为46%（12/26）。阿尔茨海默病一致和不一致的双胞胎对之间，载脂蛋白E ε4等位基因频率无显著差异。通过四分相关分析，估计遗传度约为0.6。双胞胎共同的环境因素似乎解释了大部分剩余变异。在血管性痴呆方面，单卵双胞胎（1/6 [17%]）和双卵双胞胎（4/16 [25%]）的成对一致性率，以及单卵双胞胎（2/7 [29%]）和双卵双胞胎（5/17 [29%]）的先证者一致性率均无显著差异。
遗传因素是晚发性阿尔茨海默病的主要病因，而环境因素在血管性痴呆中起主导作用。
