Guedes et al.1 measured exosomal and plasma biomarkers in veterans with a history of mild traumatic brain injury (mTBI) and tested their relationships with chronic symptoms. Neurofilament light (NfL) chain, tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-10, and vascular endothelial growth factor were measured, and the symptoms of postconcussive syndrome (PCS), posttraumatic stress disorder (PTSD), and depression were evaluated. Repetitive mTBIs are associated with elevated exosomal and plasma levels of NfL chain, with the greatest elevations in those with chronic PCS, PTSD, and depression symptoms. The authors speculated that there is a possible neuroinflammatory and axonal disruptive basis for symptoms that persist years after mTBI, especially in repetitive cases. I have a concern about their study.