APA Dictionary of Psychology

a spectrum of neurologic impairments following minor head trauma from an external force, typically involving a sudden impact or jolt to the head, leading to disruption of brain function. It is typically characterized by a loss of consciousness lasting less than 30 minutes, post-traumatic amnesia lasting less than 24 hours, and a Glasgow Coma Scale score of 13 to 15 upon initial assessment, and can include objective abnormalities on imaging (e.g., small hemorrhage). Mild TBI is the first severity tier of the formal medical classification of traumatic brain injury (mild vs moderate vs severe) and refers only to the initial severity of the brain injury, not necessarily the long-term outcomes or potential complications. Individuals with mTBI may experience subtle and transient symptoms such as headache, confusion, dizziness, visual disturbances, fatigue, irritability, and difficulty concentrating, and, in some cases, these symptoms may persist, falling under the condition known as postconcussion syndrome. Concussion is a subset of mTBI, often favored as a diagnostic term in sports medicine, pediatrics, and public communication, although the two terms are often used synonymously.