Subconcussive Preconditioning Modifies Acute Microglial Response and Improves Cognitive Outcomes Post-Concussion.

Area of Science:

• Neuroscience
• Sports Medicine
• Immunology

Background:

• Subconcussive impacts are common in contact sports and may increase concussion risk.
• The precise mechanisms linking repetitive head trauma to concussion outcomes remain unclear.
• Subconcussive impacts are known to trigger microglial responses in the brain.

Purpose of the Study:

• To investigate how subconcussive impacts influence microglial morphology and gene expression.
• To determine the effect of subconcussive preconditioning on cognitive outcomes following concussion.
• To explore the temporal relationship between subconcussive and concussive impacts on brain response.

Main Methods:

• Development and validation of a controlled cortical impact model for closed-head injuries.
• Analysis of microglial morphology and transcriptomic profiles at 1 and 9 days post-injury.
• Assessment of cognitive function using novel object recognition tests.

Main Results:

• Concussion induced transient microglial changes, while subconcussive impacts caused delayed changes.
• Subconcussive preconditioning prevented concussion-induced microglial alterations and upregulated protective genes.
• Subconcussive impacts delivered within 2 minutes of concussion abolished cognitive deficits, demonstrating a critical time window for protection.

Conclusions:

• Certain subconcussive impacts can protect against subsequent concussion and associated neuroinflammation.
• The timing of subconcussive impacts relative to concussion is crucial for their protective effect.
• Findings may inform strategies to reduce cognitive impairment in athletes with repetitive head trauma.