Burggren Alison C, Small Gary W, Sabb Fred W, Bookheimer Susan Y
Department of Psychiatry and Biobehavioral Sciences, Brain Mapping Division, UCLA School of Medicine, Los Angeles, CA 90095-7085, USA.
Am J Geriatr Psychiatry. 2002 Jan-Feb;10(1):44-51.
Previous studies with positron-emission tomography (PET) and functional magnetic resonance imaging (fMRI) have indicated differences in neural metabolism and activity between carriers of the APOE epsilon4 allele and those who are not at risk for Alzheimer disease (AD). Persons without dementia carrying the epsilon4 allele showed greater magnitude and extent of brain activation than noncarriers in regions required for memory, suggesting they performed additional cognitive work to accomplish the same task. To determine whether the fMRI differences were specific to a memory task or generalizable to any difficult cognitive task, the authors performed fMRI and compared images from 25 subjects with and without the APOE epsilon4 allele. In the most difficult conditions, all subjects showed increased MR signal in the prefrontal cortex, indicating increased cognitive effort. However, the two genetic groups showed no differences in activation patterns even at the most difficult task level, suggesting that additional cognitive effort in persons at genetic risk for AD is specific to episodic encoding and is not merely a reflection of task difficulty.
先前使用正电子发射断层扫描（PET）和功能磁共振成像（fMRI）的研究表明，携带APOEε4等位基因的个体与无患阿尔茨海默病（AD）风险的个体在神经代谢和活动方面存在差异。携带ε4等位基因且无痴呆症的人在记忆所需区域的大脑激活程度和范围比非携带者更大，这表明他们为完成相同任务需要付出额外的认知努力。为了确定功能磁共振成像的差异是特定于记忆任务还是可推广到任何困难的认知任务，作者进行了功能磁共振成像，并比较了25名携带和不携带APOEε4等位基因的受试者的图像。在最困难的条件下，所有受试者前额叶皮质的磁共振信号均增强，表明认知努力增加。然而，即使在最困难的任务水平，这两个基因组在激活模式上也没有差异，这表明有患AD遗传风险的个体额外的认知努力特定于情景编码，而不仅仅是任务难度的反映。
