Primitive-Reflex Profiling After Sport-Related Concussion: An Athlete-Centered Framework for Testing a Candidate Behavioral State Marker

Direct prospective evidence that primitive-reflex expression changes after sport-related concussion (SRC) is currently very limited. This Perspective therefore proposes a deliberately restricted context of use: standardized primitive-reflex profiling as an experimental, low-cost candidate behavioral state marker to be tested within athletes across recovery, not as an established diagnostic biomarker or a return-to-sport criterion. The standardized 18-reflex protocol underlying this framework demonstrated excellent inter-rater (κ = 0.912–1.000) and intra-rater (κ = 0.912–0.983) reproducibility in the reported 565-participant validation sample; however, athlete-specific reliability, responsiveness to SRC, construct validity, prognostic utility, and treatment sensitivity remain unestablished. We distinguish three testable candidate mechanisms—fronto-subcortical stopping-network dysfunction, altered sensorimotor/afferent gating, and vestibular–reticulospinal dysregulation—and specify findings that would support or weaken each account. A staged research program begins with sport-specific reliability and feasibility, proceeds to prospective within-athlete change beyond measurement error, and only then evaluates mechanistic convergence, incremental prognostic value, and intervention sensitivity. The full 18-reflex profile (30 bilateral or non-lateralized measurements) should remain the primary level of analysis. A summed primitive-reflex burden is retained only as a descriptive summary and must not substitute for reflex-specific analysis. Palmar grasp and Babkin-related responses provide a focused, falsifiable test case for relating lateralized reflex expression to premotor and supplementary motor hemodynamics during force-matched grasping. Progression between stages requires prespecified success criteria, independent replication, and explicit stopping rules. Until those conditions are met, primitive-reflex profiling should remain an experimental outcome embedded within guideline-concordant concussion care.