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The Relationship between Glymphatic Function (DTI-ALPS), Executive Function, and Language Production in Healthy Aging
Poster Session A, Friday, September 12, 11:00 am - 12:30 pm, Field House
Michele Diaz1, Jie Yan1, Xiaoxiao Bai1; 1Penn State University
The glymphatic (glial-lymphatic) system is a fluid-clearance pathway that clears cerebral waste products within the central nervous system. Animal studies suggest that better glymphatic clearance enhances cognitive abilities. Diffusion Tensor Imaging Analysis along the Perivascular Space (DTI-ALPS) is a recently proposed method to measure glymphatic function in the human brain (Taoka et al., 2017). The DTI-ALPS index accounts for age-related variability in structure and function (Taoka et al., 2022), where lower ALPS index correlates with smaller cerebral cortical volume and worse cognitive performance (Siow et al., 2022; Zhao et al., 2024). For example, among individuals with dementia, a lower ALPS index was correlated with worse picture naming performance (Zhao et al., 2024). Among healthy adults, the DTI-ALPS index was negatively correlated with age, and positively correlated with executive function performance in manipulation and working memory tasks (Hsiao et al., 2023). However, the relationship between DTI-ALPS and age-related differences in language production has not been examined. We examined age-related differences in the glymphatic system and its role in executive function and language production among 91 neurotypical adults (20–81 years old). We used an automated ALPS calculation (Li et al., 2024) to identify the perivascular regions of interest required to calculate the ALPS index for the left and right hemisphere. Using the mean ALPS value, we found a significant negative correlation between ALPS index and age (b=-0.002, p<.001), indicating worse glymphatic function with increasing age. To examine executive function, we used the color-word Stroop effect as a measure of inhibition ability, and the Reading Span task as a measure of working memory. To examine language production, we examined accuracy (ACC) and reaction time (RT) to a picture naming task. There was a negative correlation between the ALPS index and the Stroop interference effect (b=-163.97, p<.05), linking better glymphatic functioning with better inhibitory control (i.e., less interference). There was also a main effect of age on Stroop performance, however the ALPS index did not mediate this relationship. There was no significant relationship between the ALPS index and reading span. For performance on the picture naming task, older ages were associated with slower and less accurate picture naming (p’s < .001) and a higher ALPS index was related to faster picture naming times (b= -.0017, p < .005). Additionally, we found significant interactions between Age and ALPS index on picture naming ACC (b=0.039, p=.001) and RT (b=-.0078, p <.001) where among older adults a higher ALPS index was associated with faster and more accurate responses, and the opposite was found among younger adults. Moreover, mediation analyses indicated that the ALPS index mediated the relationship between age and picture naming RT (ALPS R2 = 17.4%, p<.001). Overall, our findings highlight the utility of the ALPS index for evaluating the relationship between cognition and healthy aging especially for inhibition and word retrieval among older adults.
Topic Areas: Language Production, Speech Motor Control