A cognitive marker for Alzheimer disease pathology in primary progressive aphasia? A validation study in the clinical setting.

Valeria Isella, Daniele Licciardo, Gaia Rebecchi, Francesca Ferri, Cinzia Crivellaro, Ildebrando Appollonio, Carlo Ferrarese

Neurobiology of aging 2023 Nov

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We validated in the clinical setting a putative clinical marker for a biological diagnosis of primary progressive aphasia (PPA) due to amyloid previously identified in an autopsy cohort and including impaired (score ≤4) digit span (DS) as index of phonological loop dysfunction and broadened criteria for logopenic PPA. In 29 PPA patients with an amyloid-positive (A+) biomarker and 28 PPA patients with an amyloid-negative (A-) biomarker, Receiver Operating Characteristics (ROC) curve analysis showed moderate specificity (71%) but insufficient sensitivity (41%) for the proposed marker. Specificity was particularly poor (58%) for the discrimination between A+ PPA and the A- subgroup with nonfluent PPA. DS may be compromised in both logopenic and nonfluent PPA, whose loci of neurodegeneration lie at the 2 ends of the left fronto-parieto-temporal system that underpins phonology. An Statistical Parametric Mapping (SPM) correlation analysis between DS score and metabolism on brain 18-fluoro-deoxy-glucose positron emission tomography also showed a major contribution of the left frontal cortex to impaired span. Copyright © 2023 Elsevier Inc. All rights reserved.

Citation

Valeria Isella, Daniele Licciardo, Gaia Rebecchi, Francesca Ferri, Cinzia Crivellaro, Ildebrando Appollonio, Carlo Ferrarese. A cognitive marker for Alzheimer disease pathology in primary progressive aphasia? A validation study in the clinical setting. Neurobiology of aging. 2023 Nov;131:153-155