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(09/11/2026) VA San Diego researchers learned higher levels of naturally occurring antibodies may protect against the depression and PTSD linked to traumatic brain injuries (TBI). Researchers measured the levels of anti-NMDAR1 autoantibodies in the blood of more than 1,000 active duty Service members before deployment. In Service members who sustained a TBI, those with the highest concentrations of these antibodies had 22% lower scores on a scale of PTSD symptoms and 25% lower scores on a scale of depression symptoms post-deployment. Those with high antibody levels also had lower psychotropic medication use. The findings suggest this naturally occurring immune protein may protect the brain against the effects of TBI, and further study could help improve depression and PTSD risk assessment and prevention. (Molecular Psychiatry, Sep 8, 2026)