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Updated: Aug 28, 2025
Advanced Diffusion Imaging in The Hippocampus of Rats with Mild Traumatic Brain Injury
Published on: August 14, 2019
White matter degradation near cerebral microbleeds is associated with cognitive change after mild traumatic brain
Andrei Irimia1, Van Ngo2, Nikhil N Chaudhari2
1Ethel Percy Andrus Gerontology Center, Leonard Davis School of Gerontology, University of Southern California, Los Angeles, CA, USA; Denney Research Center, Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA, USA.
Abstract:
To explore how cerebral microbleeds (CMBs) accompanying mild traumatic brain injury (mTBI) reflect white matter (WM) degradation and cognitive decline, magnetic resonance images were acquired from 62 mTBI adults (imaged ∼7 days and ∼6 months post-injury) and 203 matched healthy controls. On average, mTBI participants had a count of 2.7 ± 2.6 traumatic CMBs in WM, located 6.1 ± 4.4 mm from cortex. At ∼6-month follow-up, 97% of CMBs were associated with significant reductions (34% ± 11%, q < 0.05) in the fractional anisotropy of WM streamlines within ∼1 cm of CMB locations. Male sex and older age were significant risk factors for larger reductions (q < 0.05). For CMBs in the corpus callosum, cingulum bundle, inferior and middle longitudinal fasciculi, fractional anisotropy changes were significantly and positively associated with changes in cognitive functions mediated by these structures (q < 0.05). Our findings distinguish traumatic from non-traumatic CMBs by virtue of surrounding WM alterations and challenge the assumption that traumatic CMBs are neurocognitively silent. Thus, mTBI with CMB findings can be described as a clinical endophenotype warranting longitudinal cognitive assessment.
Insights
Cerebral microbleeds (CMBs) after mild traumatic brain injury (mTBI) are linked to white matter (WM) damage and cognitive decline. These CMBs indicate a specific mTBI endophenotype requiring ongoing cognitive monitoring.
Area of Science:
- Neuroimaging
- Neurology
- Brain Injury Research
Background:
- Mild traumatic brain injury (mTBI) can lead to persistent neurological deficits.
- Cerebral microbleeds (CMBs) are often found after TBI, but their impact on white matter (WM) and cognition is not fully understood.
- Distinguishing traumatic CMBs from other types is crucial for understanding their clinical significance.
Purpose of the Study:
- To investigate the relationship between CMBs in mTBI patients and subsequent white matter (WM) degradation.
- To determine if CMBs are associated with cognitive decline following mTBI.
- To characterize CMBs as a potential clinical endophenotype of mTBI.
Main Methods:
- Acquisition of magnetic resonance images from 62 mTBI adults and 203 healthy controls at approximately 7 days and 6 months post-injury.
- Quantification of CMBs in white matter (WM) and measurement of fractional anisotropy (FA) in surrounding WM streamlines.
- Correlation analysis between FA changes, CMB characteristics, and cognitive function assessments.
Main Results:
- mTBI participants showed an average of 2.7 CMBs in WM.
- At 6-month follow-up, 97% of CMBs were associated with significant WM degradation (34% ± 11% reduction in FA) within 1 cm.
- Male sex and older age were risk factors for greater WM degradation; FA changes correlated with cognitive function decline in specific pathways.
Conclusions:
- Traumatic CMBs in mTBI are associated with significant, localized white matter (WM) degradation.
- These CMBs are not neurocognitively silent and are linked to cognitive decline, challenging previous assumptions.
- mTBI with CMBs represents a distinct clinical endophenotype necessitating longitudinal cognitive assessment.
