P3-143: Clinical and Neuroimaging Differences Between Posterior Cortical Atrophy and Typical Amnestic Alzheimer's Disease Patients at Early Disease Stages

The clinical and neuroimaging characteristics between Posterior cortical atrophy (PCA) and typical amnestic AD (tAD) patients were unclear at early disease stages. Clinical symptoms and neuropsychological assessment scores were processed in enrolled 13 tAD and 16 PCA patients. The levels of Aβ42, t-tau and p-tau in both cerebrospinal fluid and serum, the volumes of bilateral hippocampi and cortical gray matter (GM), and the hypometabolism regions were analyzed. There were no significant differences in biomarkers concentrations. PCA patients showed high mean scores in the recognition and recall tests, while the mean scores in the calculation, spatial attention, shape discrimination, and writing tests were lower in PCA. The volumes of right hippocampus in PCA were larger than that in tAD, and the cortical GM volumes of bilateral parietal and occipital lobes were smaller in PCA. Hypometabolism in the bilateral parietal and occipital lobes, especially the right occipitotemporal junction, was seen in PCA. There was a significant correlation in recognition scores and recall scores with bilateral hippocampal volumes. The scores in calculation, spatial attention, and shape discrimination tasks were positively associated with GM volume in bilateral parietal lobes. And only spatial attention and shape discrimination scores were positively associated with regional glucose metabolism in parietal lobes. PCA patients displayed better recognition and recall scores and much poorer performance in spatial attention and shape discrimination tasks, which are likely associated with the larger volume of right hippocampus, the marked cortical GM atrophy, and hypometabolism in the parietal lobes.