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P1‐173: Clinical utility of amyloid imaging in the differential diagnosis of atypical/unclear dementias and its impact on caregivers
Author(s) -
Bensaïdane Mohamed Reda,
Bouchard Remi W.,
Fortin Marie-Pierre,
Houde Michèle,
Neto Pedro Rosa,
Poulin Stéphane,
Verret Louis,
Soucy Jean-Paul,
Beauregard Jean-Mathieu,
Laforce Robert
Publication year - 2015
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.2015.06.372
Subject(s) - dementia , differential diagnosis , neuroimaging , medicine , amyloid (mycology) , disease , positron emission tomography , pathology , neuropsychology , psychology , psychiatry , cognition , radiology
Background: Suspected non–Alzheimer disease pathophysiology (SNAP) has been recently defined as the presence of AD-like neurodegeneration in the absence of Ab deposition. In this study, we try to identify the pattern of cortical grey matter (GM) atrophy in cognitively unimpaired healthy elderly controls (HC) when hippocampal volume is used to define neurodegeneration, and ascertain if this pattern is different in those with or without AD pathology. Methods:320 cognitively unimpaired subjects were assessed using PET (PiB, flutemetamol or florbetapir) andMRI as part of the AIBL study. Ab status (A) was determined using CapAIBL , while neurodegeneration (N) was established using hippocampal volume (HV) measured with FreeSurfer. Following Jack et al, (2012, 2013) subjects were categorized as A-N-, A+N-, A+N+, or A-N+ (SNAP). Regional GM volumes at baseline and rates of atrophy for subjects with repeat imaging timepoints (N1⁄4135) were compared. Volumes were adjusted for age and intra-cranial volume. Statistical tests were corrected for multiple comparisons. Results: At baseline, 63% (N1⁄4203) of subjects were classified as A-N-, 15% (N1⁄448) as A+N-, 5% (N1⁄416) as A+N+, and 17% (N1⁄453) as SNAP. Compared to A-N-, A+Nhad no GM atrophy, SNAP had atrophy in all regions but the cuneus, posterior cingulate, and post-central gyrus, while A+N+ had GM atrophy in all regions except for the cuneus and pre/post-central gyri. Compared to A+N-, SNAP had significant GM atrophy in the inferior temporal (p<0.0001). Compared to SNAP, A+N+ had more atrophy in precuneus (p<0.005). SNAP had similar rates of atrophy than A-N-, A+Nhad faster atrophy rates (p<0.05) than A-Nin the temporal, precuneus and occipital, and A+N+ had faster atrophy rates (p<0.05) than A-Nin all regions but the anterior cingulate. Conclusions: At baseline, the pattern of GM atrophy in SNAP was more extensive than in A+N-, while the rates of atrophy did not differ from A-N-, suggesting SNAP, as defined by HV, comprise different underlying pathologies, and are on a different trajectory than those with AD pathology.