Pietrini P, Furey M L, Graff-Radford N, Freo U, Alexander G E, Grady C L, Dani A, Mentis M J, Schapiro M B
Laboratory of Neurosciences, National Institute on Aging, Bethesda MD 20892, USA.
Am J Psychiatry. 1996 Oct;153(10):1261-8. doi: 10.1176/ajp.153.10.1261.
A subgroup of patients with Alzheimer's disease present with visual disturbances at onset. This study investigated whether specific cortical networks associated with visual processes are preferentially affected in this subgroup and determined the clinical implications of such abnormalities.
Regional cerebral glucose metabolic rates were assessed with positron emission tomography and [18F]2-fluoro-2-deoxy-D-glucose, and general intellectual functions, memory, and visual skills were measured with cognitive tests in patients with probable Alzheimer's disease-10 with and 22 without prominent visual symptoms-and in 25 healthy comparison subjects.
Both patient groups showed reduced glucose metabolism in parietal regions and in middle and superior temporal regions in comparison with the healthy subjects. The Alzheimer's disease patients without visual symptoms also showed reductions in inferior temporal, frontal, and limbic structures, as is typical of Alzheimer's disease. In contrast, the patients with visual symptoms had larger metabolic deficits than the patients without visual symptoms in the parietal and occipital cortices (including the primary visual cortex), with a relative sparing of inferior temporal, frontal, and limbic regions. Consistently, the patients with visual symptoms had significantly greater visuospatial deficits and less severe memory impairments than the patients without visual symptoms.
Alzheimer's disease patients with visuospatial deficits who are studied while alive have a distinctive regional distribution of cerebral metabolic impairment that is related to specific cognitive deficits and that distinguishes them from patients with typical Alzheimer's disease. These findings imply that regional variations in brain dysfunction can occur in Alzheimer's disease, with differential involvement of cortical systems resulting in distinctive clinical subgroups.
一部分阿尔茨海默病患者在发病时伴有视觉障碍。本研究调查了与视觉过程相关的特定皮质网络在该亚组患者中是否受到优先影响，并确定了此类异常的临床意义。
采用正电子发射断层扫描和[18F]2-氟-2-脱氧-D-葡萄糖评估局部脑葡萄糖代谢率，并通过认知测试测量可能患有阿尔茨海默病的患者（10例有明显视觉症状，22例无明显视觉症状）以及25名健康对照者的一般智力功能、记忆力和视觉技能。
与健康受试者相比，两组患者的顶叶区域以及颞中、颞上区域的葡萄糖代谢均降低。无视觉症状的阿尔茨海默病患者还表现出颞下回、额叶和边缘结构的代谢降低，这是阿尔茨海默病的典型表现。相比之下，有视觉症状的患者在顶叶和枕叶皮质（包括初级视觉皮质）的代谢缺陷比无视觉症状的患者更大，而颞下回、额叶和边缘区域相对较少受累。一致地，有视觉症状的患者比无视觉症状的患者有更明显的视觉空间缺陷和较轻的记忆障碍。
生前研究的有视觉空间缺陷的阿尔茨海默病患者具有独特的脑代谢损害区域分布，这与特定的认知缺陷相关，并将他们与典型阿尔茨海默病患者区分开来。这些发现表明，阿尔茨海默病可能存在脑功能障碍的区域差异，皮质系统的不同受累导致了独特的临床亚组。
