Long-Term Postdeployment Clinical Subtypes of Risk and Resiliency in Brain Injury and Neurodegeneration.

Area of Science:

• Neuroscience
• Traumatic Brain Injury Research
• Military Health

Background:

• Limited research exists on longitudinal neurodegenerative outcomes post-deployment.
• Understanding trajectories of neurodegeneration is crucial for assessing later-life dementia risk.

Purpose of the Study:

• To analyze longitudinal outcomes and MRI data from US military personnel over 10 years.
• To identify profiles of neurodegenerative resilience and risk following combat deployment.

Main Methods:

• Prospective longitudinal cohort study of 288 combat-deployed service members.
• Included groups with and without mild traumatic brain injury (TBI) from blast or blunt trauma.
• Assessed clinical outcomes (neurobehavioral, psychological, cognitive) and structural MRI at 1, 5, and 10 years post-deployment.

Main Results:

• Four distinct 10-year post-deployment clinical outcome subtypes were identified using k-means clustering.
• Significant differences in brain volume, particularly cerebellum and brainstem, were observed between clusters.
• The cluster with severe cognitive dysfunction showed the lowest brain volumes.

Conclusions:

• Clinical outcome clustering identified evolving post-deployment subtypes in service members.
• Regional brain volume differences correlated with these subtypes years prior.
• Findings emphasize the heterogeneity of mild TBI and its long-term outcomes.