The Relationship between History of Traumatic Brain Injury and Longitudinal Changes in Cortical Thickness among Patients with Alzheimer’s Disease

Background There has been little direct examination of how traumatic brain injury (TBI) affects the rate of neurodegeneration for individuals with Alzheimer’s disease (AD). Methods The study examined 89 cognitively normal adults (65 with and 24 without prior TBI) and 65 with AD (16 with and 49 without prior TBI). Cortical thickness was quantified from T1-weighted MRI scans at baseline and follow-up (mean interval 33.4 months). Partial least squares analysis was used to evaluate the effects of AD and TBI history on the longitudinal change in cortical thickness. Results Significant group effects were identified throughout the frontal and temporal cortices. Comparison of the AD groups to their control cohorts showed greater relative atrophy for the AD cohort with prior TBI. Conclusion These results indicate that a history of TBI exacerbates longitudinal declines in cortical thickness among AD patients, providing new insights into the shared pathomechanisms between these neurological conditions.