Prevalence and clinical associations of atrophy subtypes using clinical routine image analysis software in MCI patients from a memory clinic population

Abstract

AbstractBackgroundThree patterns of brain atrophy have been consistently identified in cases of Alzheimer’s dementia [1]: a limbic‐predominant (LP) phenotype, with atrophy of the hippocampus but relatively spared neocortex; a hippocampal sparing (HS) phenotype, with atrophy in the cortex (especially lateral temporal and parietal lobes) but sparing of the hippocampus; and a typical/diffuse (TD) phenotype that presents with atrophy in both. A recent study extended this concept to a less severely affected memory clinic population (the MEMENTO Study). Here, we assessed atrophy subtypes in that same population using an approach based on the output of QyScore® an FDA‐approved and CE‐marked image analysis software.Method1642 MCI participants from the MEMENTO cohort (Age 71±9, MMSE 27.8±2.0, CDR‐SB 0.6±0.7) had 3DT1 MRI scans analyzed with QyScore®. 678 (41%) had amyloid status from CSF or PET, of which 193 (28%) were amyloid‐positive (A+). Neurodegeneration‐positive (N+) atrophy subtypes were defined on individual scans using z‐scores from parietal cortex and hippocampus volumes referenced to 1290 cognitively normal individuals. LP and HS were defined by atrophy (z<‐1.64) of parietal lobe or hippocampus only, and TD by atrophy in both structures (otherwise N‐).ResultThe proportion of single‐domain amnestic (aMCIsd), multi‐domain amnestic (aMCImd), single‐domain non‐amnestic (naMCIsd) and multi‐domain non‐amnestic (naMCImd) individuals was 10%, 50%, 21% and 18% respectively. N+ subtypes were more prevalent in amnestic (aMCIsd 18%, aMCImd 17%) than non‐amnestic (naMCIsd 8%, naMCImd 10%) presentations. N+ subtypes were more common in A+ participants, especially the amnestic presentations (aMCIsd 42%, aMCImd 29%). Overall, the HS subtype was the most common (8% of all cases, 16% of A+ cases), followed by LP (4%/6%) and TD (2%/3%). The LP subtype was more prevalent in amnestic presentations.ConclusionThe relatively low prevalence of the TD subtype in this cohort is consistent with [2]. The overall prevalence of N+ subtypes in MEMENTO by this method is intermediate between those previously reported using a similar method for ADNI CN A+ and aMCI A+ cohorts [3].[1] Ferriera et al. (2020) Neurology 94:436 [2] Planche et al. (2021) Alz & Dem 17(4):651 [3] Charil et al. (2018) AAIC