Rethinking classification of primary progressive and post-stroke aphasia


  • 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.