MMP9 and post-traumatic stress disorder: High MMP-9 levels, particularly in the Past PTSD (≤5 y) group (median: 418.70 ng/mL, IQR: 341.08–558.19, Section 2.1, Table 1), are known to enhance glutamate release and impair astrocytic glutamate uptake, leading to excessive excitatory signaling [2].