The Effect of Age on Post-Stroke Language Outcomes.

Introduction: This study investigates how chronological age at stroke onset affects post-stroke language abilities and recovery. Using cross-sectional and retrospective data, we investigated (A) which language tasks are sensitive to age; (B) whether any age-related effects are modified by factors such as lesion size, initial severity and education and (C) whether age influences recovery from aphasia. Methods: Language abilities were assessed in 749 participants using (i) the Comprehensive Aphasia Test (CAT) at a single time point and (ii) self-reported measures of speaking, understanding, reading and writing ability both at 1 week and 1 year post-stroke. The outcomes investigated, using multiple linear regression, were (1) CAT language scores and (2) self-reported recovery scores at 1 year post-stroke. Lesion size, initial severity, sex, handedness, pre-stroke education and time post-stroke were controlled. Bayesian statistics assessed the strength of evidence for observed effects. Results: (A) Irrespective of lesion or symptom severity, older age at stroke onset was associated with worse performance across multiple language domains, including overall language ability, nonword and word repetition, semantic and letter fluency, object naming and comprehension of spoken and written words and sentences. Effect sizes were strongest for nonword repetition ( Conclusion: Older age at stroke onset significantly worsened language outcomes, highlighting the sensitivity of aphasia assessments to age-related differences in post-stroke language abilities. This disadvantage was greatest in participants with both large lesions and severe initial symptoms. Considering age when interpreting assessment scores would optimise diagnosis and prognostic accuracy.