Table 2.
Neuropathological findings associated with the three primary progressive aphasia (PPA) variants.
| Variable | svPPA | nfvPPA | lvPPA |
|---|---|---|---|
| Disease epicenter | Anterior temporal lobe (L>R) | Left posterior fronto-insular cortex | Left posterior perisylvian or parietal cortex |
| Typical neuropathology | TDP-43C | Tau (CBD/PSP) | Alzheimer's disease (AD) |
| Modality | Evidence for PPA | ||
| Structural MRI (T1) | a Predominant atrophy or cortical thinning in disease epicenter | ||
| Perfusion imaging (ASL, MRI, or SPECT) | a Predominant hypoperfusion (lower signal) in disease epicenter | ||
| FDG-PET (F-18 fluorodeoxyglucose PET) | a Predominant hypometabolism (lower signal) in disease epicenter | ||
| Tau-PET ( b 18F-Flortaucipir PET) | Predominant tau aggregation (high signal) in disease epicenter in lvPPA and (to a lesser extent) in nfvPPA; the relation between tau aggregation and symptoms is unclear for svPPA | ||
| Amyloid-PET ( b 11C-labeled Pittsburgh Compound-B PET) | Elevated levels of amyloid (high signal) distributed along cortex indicates AD, which is closely associated with lvPPA; little or no amyloid (low signal) in nfvPPAand svPPA | ||
| Cerebrospinal fluid (CSF) via lumbar puncture | Decreased levels of Aβ and increased levels of total tau and phosphorylated tau compared to healthy controls indicates probable AD pathology, which is strongly linked to lvPPA | ||
Note. svPPA = semantic variant primary progressive aphasia; nfvPPA = nonfluent/agrammatic variant primary progressive aphasia; lvPPA = logopenic variant primary progressive aphasia; CBD = corticobasal degeneration; PSP = progressive supranuclear palsy; MRI = magnetic resonance imaging; ASL = arterial spin labeling; SPECT = single-photon emission computed tomography.
a
Imaging-supported criteria for variant classification in Gorno-Tempini et al. (2011).
b
Alternative labels for 18F-Flortaucipir and 11C-labeled Pittsburgh Compound-B are 18F-AV-1451 and 11C-PiB, respectively.