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[IC‐P‐143]: SOFTWARE COMPARISONS FOR SUBCORTICAL MEASUREMENTS IN HEALTHY OLDER ADULTS ACROSS ADNI AND PPMI
Author(s) -
Rane Swati,
Plassard Andrew,
Landman Bennett,
Donahue Manus J.,
Claassen Daniel O.
Publication year - 2017
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1016/j.jalz.2017.06.2417
Subject(s) - putamen , bonferroni correction , white matter , neuroimaging , medicine , amygdala , neuroscience , nuclear medicine , psychology , magnetic resonance imaging , radiology , statistics , mathematics
Background:Posterior cortical atrophy (PCA) is a progressive visual syndrome that affects the posterior part of the brain and is most commonly caused by Alzheimer’s disease (AD). It has been previously suggested that three main subgroups exist: primary visual (the striate cortex, caudal), parietal (dorsal) and occipito-temporal (ventral) (Ross et al., 1996, Galton et al., 2000). However, evidence for the existence of these groups is mainly limited to individual case reports (Ross et al., 1996, Galton et al., 2000) and no previous study looked at the temporal progression of brain atrophy in such subgroups. The aim of the present study was to explore temporal patterns of atrophy in different behavioural subgroups as defined by neuropsychological data. Methods: We analysed 78 controls and 55 PCA subjects using 25 region-of-interest volumes derived from T1-weighted MRI scans. The PCA patients were divided into three subgroups. We first ranked them based on the difference between early visual tests and memory tests, and the lowest 1/3 of subjects were assigned to the “vision” subgroup, typically associated with caudal impairment. We split the remaining 2/3 into two halves: a “space” subgroup with worse performance on spatial processing tasks, typically associated with dorsal stream impairments and an “object” subgroup with worse performance on perceptual tasks, normally associated with ventral stream impairments. We fit an Event-Based Model (EBM) (Fontejin et al., 2012) for each subgroup to estimate the order in which brain regions become abnormal. Results: For the vision subgroup (Fig. 1a-b) our model suggests occipital areas are the first to become affected by the disease. For the space subgroup (Fig. 2a-b) our model suggests atrophy starts in the superior parietal area (dorsal pattern) but occipital and temporal areas are also involved. For the object subgroup (Fig. 3ab) atrophy starts in the inferior occipital area and spreads to the temporal areas (ventral pattern). Conclusions:Our model predicts that different cognitive profiles in PCA patients correspond to distinct longitudinal patterns of atrophy. While these subgroups show differences in the longitudinal progression of atrophy, they might represent points in a continuum of phenotypical variation within PCA, as suggested by Lehmann et al., 2011.