Aphasia

The scope of this page is acquired aphasia in adults (18+). See the Aphasia Evidence Map for pertinent scientific evidence, expert opinion, and client/caregiver perspectives. For research about neurodegenerative aphasia, see the Primary Progressive Aphasia Evidence Map.

Aphasia is an acquired neurogenic language disorder resulting from an injury to the brain, typically the left hemisphere, that affects the functioning of core elements of the language network. Aphasia involves varying degrees of impairment in four primary areas:

  • spoken language expression
  • written expression
  • spoken language comprehension
  • reading comprehension

Aphasia may also result from neurodegenerative disease. For example, primary progressive aphasia is a subtype of frontotemporal dementia in which language capabilities become progressively impaired. Discussion of neurodegenerative disease is beyond the scope of this page. For further information, please see ASHA’s Practice Portal page on Dementia, the Primary Progressive Aphasia Evidence Map, and the items listed in the Resources section at the end of this page.

Aphasia is often described as nonfluent or fluent, based on the typical length of utterance and amount of meaningful content a person produces. There are various subtypes of aphasia within these two categories based on differences in other aspects of expressive and receptive language skills. Clinicians should be aware that a person’s presentation may not fit into a single aphasia type or subtype, and should use care if designating a type or subtype. Aphasia’s presentation may also change over time as communication improves with recovery. For further discussion of subtypes please see Sheppard & Sebastian, 2021.

The recovery arc of aphasia varies significantly from person to person. The most predictive indicator of long-term recovery is initial aphasia severity, along with lesion site and size (Benghanem et al., 2019; Hillis et al., 2018; Kristinsson et al., 2022; Plowman et al., 2012; Watila & Balarabe, 2015). Factors that may negatively affect improvement include poststroke depression (Berg et al., 2003) and social isolation after aphasia onset (Hilari & Northcott, 2006; Vickers, 2010).

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