Abstract
Simultanagnosia is a common symptom of posterior cortical atrophy, and its association with brain structural and functional changes remains unclear. In our study, 18 posterior cortical atrophy patients with simultanagnosia, 29 patients with Alzheimer’s disease and 20 cognitively normal controls were recruited and subjected to full neuropsychological evaluation, including simultanagnosia tests, and structural and resting-state functional MRI. The gray matter volume was assessed by voxel-based morphometry, while the intrinsic functional connectivity was evaluated using the reduced gray matter volume regions of interest as the seed. In contrast to the patients with Alzheimer’s disease, those with posterior cortical atrophy showed the following: (1) markedly lower simultanagnosia test scores, (2) an altered regional gray matter volume of the left middle occipital gyrus and ventral occipital areas, and (3) lowered intrinsic functional connectivity with the left middle occipital gyrus, left lingual gyrus and right middle occipital gyrus separately. Additionally, the gray matter volume of the left middle occipital gyrus and left inferior occipital gyrus were each correlated with simultanagnosia in posterior cortical atrophy patients. The intrinsic functional connectivity of the left middle occipital gyrus with the right superior occipital gyrus and that of the right middle occipital gyrus with the left superior parietal gyrus were also correlated with simultanagnosia in posterior cortical atrophy patients. In summary, this study indicated that simultanagnosia is associated with gray matter reductions and decreased functional connectivity in the left middle occipital gyrus and the left inferior occipital gyrus in patients with posterior cortical atrophy.
Highlights
As observed in wounded veterans with visuospatial impairment (Hughes, 1970) and more systematically described by Benson et al in (1988), posterior cortical atrophy (PCA) is a clinical syndromeYue Cui, Yang Liu and Caishui Yang have contributed to this work.1 3 Vol.:(0123456789)Brain Imaging and Behavior appear together but can do so when each object appears separately (Crutch et al, 2011)
Another study used single photon emission computed tomography (SPECT) to examine an Alzheimer’s disease (AD) group and a PCA group with matched Mini-Mental State Examination (MMSE) scores; the study found that hypoperfusion in the right inferior occipital gyrus and bilateral middle occipital gyri was related to simultanagnosia (Kas et al, 2011)
No statistically significant difference was found in age, years of education or sex ratio, while significant differences were shown in the Trail Making Test (TMT) A test (F = 39.44; p < 0.01), reading test (F = 21.26; p < 0.01) and facial agnosia test (F = 10.28; p < 0.01) among the three groups; the PCA group performed worse than the other group
Summary
As observed in wounded veterans with visuospatial impairment (Hughes, 1970) and more systematically described by Benson et al in (1988), posterior cortical atrophy (PCA) is a clinical syndromeYue Cui, Yang Liu and Caishui Yang have contributed to this work.1 3 Vol.:(0123456789)Brain Imaging and Behavior appear together but can do so when each object appears separately (Crutch et al, 2011). Two case reports documented the specific encephalic changes in cerebral ischemia patients who had simultanagnosia using structural magnetic resonance imaging (sMRI) and single photon emission computed tomography (Sakurai et al, 2016, 2018). A case–control study published in 2016 comparing sMRI findings between 12 PCA subjects and 12 healthy controls reported that white matter atrophy within the left association fiber pathway results in simultanagnosia. Another study used single photon emission computed tomography (SPECT) to examine an AD group and a PCA group with matched Mini-Mental State Examination (MMSE) scores; the study found that hypoperfusion in the right inferior occipital gyrus and bilateral middle occipital gyri was related to simultanagnosia (Kas et al, 2011)
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