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Disconnections Related to White Matter Hyperintensities Predict Semantic Memory Impairments in Post-Stroke Aphasia
Poster Session C, Friday, October 25, 4:30 - 6:00 pm, Great Hall 3 and 4
Ida Rangus1, Natalie Busby1, Rebecca W. Roth2, Janina Wilmskoetter3, Julius Fridriksson1, Leonardo Bonilha4; 1Communication Sciences and Disorders, University of South Carolina, Columbia, SC, USA, 2Department of Neurology, Emory University, Atlanta, GA, USA, 3Department of Rehabilitation Sciences, College of Health Professions, Medical University of South Carolina, Charleston, SC, USA, 4School of Medicine Columbia, University of South Carolina, Columbia, SC, USA
Background: Semantic memory impairments in post-stroke aphasia refer to difficulties in accessing or retrieving knowledge about the world, including understanding the meaning of words, concepts, and facts. These impairments can manifest as challenges in naming objects, comprehending spoken and written language, and using appropriate vocabulary, significantly affecting communication and daily functioning. Such deficits may arise from damage to white matter pathways caused by stroke lesions that disrupt connections between critical language and memory regions. The presence of white matter hyperintensities (WMH), a marker of reduced brain health, may exacerbate these disconnections and potentially worsen semantic memory impairments. Our aim was to assess whether semantic memory performance is better explained by combined disconnections from stroke lesions and WMH, compared to disconnections from stroke lesions alone. Methods: Seventy-two individuals with chronic left-hemisphere stroke (mean age at testing: 58.4 ± 13.1 years, mean stroke lesion volume: 133.2 ± 95.6 cc; 31 females [43.1%]) underwent MRI and behavioral assessments. Stroke lesions were manually delineated on T2-weighted images, and WMH were identified from FLAIR images using FSL’s automated segmentation tool BIANCA. Using the Lesion Quantification Toolkit, we quantified the percentage of disconnection within association tracts relative to the whole tracts due to stroke lesions and WMH, respectively. Semantic memory was assessed using the Pyramids and Palm Trees Test (PPTT). To determine whether stroke- and WMH-related disconnections together explained more variance in semantic memory performance than disconnections due to stroke lesions alone, we ran two multiple linear regression models with PPTT as the dependent variable: 1.) the Stroke Lesion Model included only disconnections due to stroke lesions, controlling for age, sex, education, lesion volume and aphasia severity (measured by Western Aphasia Battery revised Aphasia Quotient - WAB-R-AQ), 2.) the Combined Lesion and WMH Model included both disconnections due to stroke lesions and WMH, with the same covariates. Adjusted R² values of the two models were compared using ANOVA to determine whether adding disconnections due to WMH significantly improved the model fit. Results: Stroke Lesion Model explained 8.9% of the variance in semantic memory performance (Adj. R² = .089, F(6, 66) = 2.169, p = .057), with only WAB-R-AQ as a significant predictor (t = 2.443, p = .017). The Combined Lesion and WMH Model explained 24.9% of the variance in semantic memory performance (Adj. R² = .249, F(7, 65) = 4.412, p < .001), with disconnections from WMH as the only significant predictor (t = -3.884, p < 0.001). Including disconnections from WMH significantly improved model fit over disconnections from stroke lesions alone (ΔF(1, 65) = 15.089, p < .001). Discussion: White matter disconnections from WMH significantly impact semantic memory performance in individuals with post-stroke aphasia. Incorporating WMH disconnections substantially enhances the ability to explain variance in semantic memory deficits, beyond the effects of disconnections caused by stroke lesions alone. This finding emphasizes the importance of considering overall brain health in understanding cognitive-communication impairments in post-stroke aphasia.
Topic Areas: Disorders: Acquired, Control, Selection, and Executive Processes