Concussion Clinical Subtypes and Modifiers: A Framework for Longitudinal Study of Low-Level Blast Exposure

Blast overpressure (BOP) exposure is an important, evolving, and highly visible topic with growing operational, clinical, and policy relevance for the U.S. Armed Forces. Special Operations Forces (SOF) personnel are particularly vulnerable to repeated sub-concussive events from BOP because of their operational role and tempo, but conventional forces and other high-risk occupational groups may also experience meaningful cumulative exposures. Recent Congressional actions, including provisions in the National Defense Authorization Acts establishing blast safety oversight and standardized monitoring, underscore the urgency of improving BOP risk management, surveillance, and research. Although BOP-related brain injury may represent a distinct health condition, the lack of a pathognomonic diagnostic criterion often results in it being considered analogous to, or on the continuum of, mild traumatic brain injury (concussion). Diagnosing BOP-related injury and its sequelae remains a challenge, and consensus on an acceptable threshold for occupational BOP exposure has not yet been determined. Overlap in symptom presentation between BOP-related effects and concussion further complicates identification, clinical management, and longitudinal monitoring, particularly in the absence of validated diagnostic tools or BOP-specific clinical guidelines. Rehabilitation following concussion has increasingly focused on identifying clinical subtypes (vestibular, ocular-motor, cognitive, anxiety/mood, post-traumatic headache) and modifiers (sleep, cervical spine) to inform symptom-targeted treatments, guide specialty referral, and improve outcomes. This subtype-based approach has enhanced clinical decision-making in concussion care and provides a pragmatic framework for addressing heterogeneous symptom presentations. We propose extending this established concussion clinical subtype framework to guide future longitudinal research and management of BOP-related effects, leveraging symptom-based classification alongside exposure documentation and objective assessments. The purpose of this commentary is to outline a conceptual framework for the longitudinal study of BOP exposure and its potential effects, integrating baseline assessment, exposure monitoring, serial clinical evaluation, and emerging biomarkers to include advanced neuroimaging approaches. Adoption of a standardized, subtype-informed longitudinal approach has the potential to improve understanding of BOP-related effects, support return-to-duty and risk management decisions, and inform the development of evidence-based policies aimed at protecting brain health, optimizing performance, and enhancing readiness in military personnel.