Classifying post-stroke aphasia (PSA) and primary progressive aphasia (PPA) in terms of graded variation in four key dimensions may be a more effective way of understanding where patients are situated in the spectrum of aphasia compared to the application of discrete subtype categories.
Why this matters
Aphasia, defined as an impaired ability to comprehend and formulate language, affects many aspects of linguistic communication including reading, auditory comprehension and expressive language.
Language impairments resulting from stroke (i.e. PSA) or neurodegeneration (i.e. PPA) have rarely been directly compared in the literature despite significant overlap in the conditions.
Categorical subtypes of PSA and PPA are often insufficient, with many patients falling into the “mixed” category, suggesting that a spectrum of subtypes exists rather than discrete, mutually exclusive subtypes.
Alternative, non-categorical classification systems making use of a ‘multidimensional space’ defined by dynamic scales of phonology, semantics, speech fluency and non-language cognitive skills, which have emerged in the field of PSA, may be a more effective way of meaningfully situating patients with aphasia including PPA.