Introduction: Transient ischemic attack (TIA) greatly increases the risk of developing dementia later in life. Measurement of microstructural changes in white matter (WM) using diffusion tensor imaging (DTI) tractography has potential for identifying those at greatest risk of cognitive decline. We hypothesized that patients presenting with TIA have abnormal DTI measures in major WM tracts. Our objective was to determine changes in DTI measures for fractional anisotropy (FA) and medial diffusivity (MD) in frontoparietal (Superior Longitudinal Fasciculus; SF) and medial temporal (Uncinate Fasciculus; UF) WM tracts for TIA patients and healthy controls.
Methods: Patients presenting with symptoms of high risk TIA but free of dementia, and healthy volunteer controls were recruited acutely. Structural MRI, inclusive of DTI sequences (31 directions b1000) was performed. FA and MD values were collected in the left and right SLF and UF. Multiple linear regression was performed to determine predictors of DTI values (FA and MD), adjusted for age. Subject’s cognition was screened using Montreal Cognitive Assessment (MoCA).
Results: Data from 60 TIA patients (mean age = 68.75 years, SD = 9.39, 45% female) and 33 healthy controls (mean age = 64.97 years, SD = 10.45, 67% female) was analyzed. Linear regression identified that TIA patients have higher FA values in left SLF, F(2, 90) = 9.210, p < .001, R2 = .170); right SLF, F(2, 90) = 7.154, p = .001, R2 = .137; and left UF, F(2, 90) = 3.513, p = .034, R2 = .072, compared to healthy controls. No group changes in MD were observed when corrected for age. TIA patients (median score 24, (interquartile range (IQR) = 5) performed worse than healthy controls (median score = 27, IQR = 4) on the MoCA while controlling for age, F(1, 90) = 7.689, p < .007.
Conclusion: TIA patients showed changes in FA of WM tracts related to language and memory function when compared to healthy controls, supporting the presence of incipient microstructural disease. Our results show that measures of microstructural changes using DTI may help identify TIA patients at a greater risk of developing cognitive impairment. Future work aims to identify deterioration of DTI measures over time and their relation to potential vascular and neurodegenerative etiologies.