Stroke Damage Can Disrupt Use of Word Meanings in Reading

A new study has identified how stroke can affect a person’s ability to use word meanings during reading – a finding that provides insight into the neurobiology of reading and could inform future research into rehabilitation approaches.

While it is well-established that stroke can impair reading ability, the mechanisms behind this deficit have been unclear. Researchers at Georgetown University have now shown that damage from stroke may interfere with the brain’s capacity to draw on word meanings to aid in word recognition during reading.

The study, published August 13 in Brain, examined reading performance and brain imaging data from 56 individuals who had experienced a left-hemisphere stroke and 68 individuals with no history of stroke. The left hemisphere is typically responsible for language processing.

Understanding meaning-based reading impairment

The research focused on how participants read words with different levels of “imageability” – a measure of how easily a word evokes a mental image. Words like “hammer” and “cow” are high in imageability, whereas abstract terms like “justice” have lower imageability.

By using MRI to assess the extent of stroke damage, the researchers identified a key brain region – the superior temporal sulcus – that was associated with impaired use of semantic information during reading. This region is involved in processing speech and auditory short-term memory. Damage to this area was linked to reduced advantage in reading high imageability words, suggesting that some stroke survivors are unable to use word meanings as a reading aid.

The findings indicate that, in these cases, individuals may struggle to connect the pronunciation of a word with its underlying concept, a process that normally supports fluent reading.

“We usually think of reading in our daily lives as a way to gain meaning, but the opposite is also true: we rely on a word’s meanings to help us recognize it when reading.”

Dr. Peter E. Turkeltaub.

Mapping reading-related brain function

The research team also identified overlap between regions responsible for phonological processing – the ability to sound out words – and those involved in semantic-phonological integration. This suggests that the inability to use meaning during reading may result from disruptions in linking word meanings to their spoken forms.

Phonological impairment is a common consequence of stroke, but this study highlights a less frequently recognized type of reading difficulty. While phonological deficits were more common and severe in the study group, semantic impairment also emerged as a distinct and measurable challenge.

Next steps in stroke-related language research

This work adds to the understanding of how brain injuries impact language systems and identifies a specific deficit affecting reading. The authors noted that future studies, including a new five-year project funded by the National Institutes of Health, will compare reading abilities in people with left-hemisphere stroke to those of older adults without stroke to explore how language changes with aging and brain injury.

Reference: Staples R, Dickens JV, Dyslin SM, et al. Meaning for reading: the neurocognitive basis of semantic reading impairment after stroke. Brain. 2025:awaf253. doi: 10.1093/brain/awaf253

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