Study finds long-term neurodegeneration in all severities of TBI
By Kaitlyn Chen. This article was initially published in the 7/25/24 edition of our Concussion Update newsletter; please consider subscribing.
Trigger warning: This synopsis discusses traumatic brain injury (TBI), neurodegeneration, and cognitive impairments. It includes details about the long-term effects of TBIs, brain volume loss, and related medical conditions. If these topics are distressing or triggering, please proceed with caution.
A study published in Alzheimer’s & Dementia found that neurodegeneration is “progressive and continues for many years after mild head trauma without signs of brain injury on conventional MRI.” The study included 143 mild, moderate, and severe TBI patients and 43 controls, with participants tested at various intervals from 30 days to 5 years after their injury. Data was collected using blood tests, MRIs, and cognitive tests over a 9-year period. All severities of TBIs experienced the same amount of brain volume loss but in different brain regions; mild TBI was associated with atrophy in gray matter, while moderate to severe TBIs were associated with atrophy in subcortical gray matter or white matter.
On a more optimistic note, both mild and moderate to severe TBI patients showed cognitive improvement after their concussion, although those with more severe TBIs performed slightly worse. The study authors explain that “the relationship between cognitive performance and neurodegeneration after TBI is complex, and suggests two distinct processes, in which there is an interaction between them early on, followed by a divergence in the years after injury.” In other words, there are opportunities for cognitive improvement despite neurodegeneration.
In addition, they found that serum NfL and GFAP, neuronal proteins, and initial TAI (traumatic axonal injury) can serve as biomarkers of neurodegeneration in patients with TBI. These biomarkers offer the potential for noninvasive detection of elevated risk of neurodegeneration immediately after a TBI, as well as tracking neurodegeneration over time, post-TBI. The study authors suggest that biomarkers can also be used in research to evaluate the effects of therapies on post-concussion symptoms or research into other neurodegenerative diseases.
Limitations of this study include missing data at certain time points, fewer MRI scans for controls to evaluate age-related brain atrophy, and a slightly imbalanced proportion of TBI severities.
