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Abstract
Background and Objectives The aims of this work were to compare rates of longitudinal change in neurologic and neuropsychological test performance between the logopenic progressive aphasia (LPA) and posterior cortical atrophy (PCA) variants of atypical Alzheimer disease (AD) and to use unbiased principal component analysis to assess heterogeneity in patterns of change and relationships to demographics and concurrent brain atrophy.
Methods Patients with PCA or LPA who were positive for amyloid and tau AD biomarkers and had undergone serial neurologic and neuropsychological assessments and structural MRI were identified. Rates of change in 13 clinical measures were compared between groups in a case-control design, and principal component analysis was used to assess patterns of clinical change unbiased by clinical phenotype. Components were correlated with rates of regional brain atrophy with tensor-based morphometry.
Results Twenty-eight patients with PCA and 27 patients with LPA were identified. Those with LPA showed worse baseline performance and faster rates of decline in naming, repetition, and working memory, as well as faster rates of decline in verbal episodic memory, compared to those with PCA. Conversely, patients with PCA showed worse baseline performance in tests of visuospatial and perceptual function and on the Clinical Dementia Rating Scale and faster rates of decline in visuoperceptual function compared to those with LPA. Principal component analysis showed that patterns of clinical decline were highly heterogeneous across the cohort, with 10 principal components required to explain >90% of the variance. The first principal component reflected overall severity, with higher scores in LPA than PCA reflecting faster decline in LPA, and was related to left temporoparietal atrophy. The second and third principal components were not related to clinical phenotype but showed some relationship to regional atrophy. No relationships were identified between the principal components and age, sex, disease duration, amyloid PET findings, or apolipoprotein genotype.
Discussion Longitudinal patterns of clinical decline differ between LPA and PCA but are heterogeneous and related to different patterns of topographic spread. PCA is associated with a more slowly progressive course than LPA.
Glossary
- AD=
- Alzheimer disease;
- AVLT=
- Auditory Verbal Learning Test;
- AVLT RPC=
- AVLT recognition percent correct;
- BDAE-R=
- Boston Diagnostic Repetition;
- BNT=
- Boston Naming Test;
- CBI=
- Cambridge Behavioral Inventory;
- CDR-SB=
- Clinical Dementia Rating Scale sum of boxes;
- LPA=
- logopenic progressive aphasia;
- MCALT=
- Mayo Clinic Adult Lifespan Template;
- MDS-UPDRS III=
- Movement Disorders Society–sponsored revision of the Unified Parkinson's Disease Rating Scale part III;
- MICE=
- multiple imputation by chained equations;
- MoCA=
- Montreal Cognitive Assessment Battery;
- MPRAGE=
- magnetization-prepared rapid gradient echo;
- PCA=
- posterior cortical atrophy;
- PiB=
- Pittsburgh compound B;
- Rey-O=
- Rey-Osterrieth;
- SUVR=
- standard uptake value ratio;
- VOSP=
- Visual Object and Space Perception;
- WAB=
- Western Aphasia Battery;
- WMS=
- Wechsler Memory Scale
Footnotes
Go to Neurology.org/N for full disclosures. Funding information and disclosures deemed relevant by the authors, if any, are provided at the end of the article.
Submitted and externally peer reviewed. The handling editors were Rawan Tarawneh, MD, and José Merino, MD, MPhil, FAAN.
CME Course: NPub.org/cmelist
- Received June 29, 2021.
- Accepted in final form February 21, 2022.
- © 2022 American Academy of Neurology
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