Major or Mild Neurocognitive Disorder Due to Traumatic Brain Injury

Clinical picture

• Slowed processing speed, divided-attention failure, and word-finding pauses dominate, and patients describe mental fog and effortful thinking.
• Neurobehavioral change is often disproportionate to test scores: irritability, low frustration tolerance, disinhibition, emotional lability, and apathy.
• Duration of post-traumatic amnesia predicts outcome better than initial Glasgow Coma Scale score, and patients rarely recall the injury itself.
• Somatic symptoms cluster with the cognitive ones: headache, dizziness, photophobia, noise sensitivity, fatigue, and fragmented sleep.
• Frontal injury produces intact knowledge with failed application, so patients describe the correct plan in clinic and cannot execute it at home.
• Symptoms worsen under fatigue, time pressure, and sensory load, which is why deficits surface at work long before they show up on office testing.

Criteria snapshot

• Requires evidence of head impact or rapid brain movement plus at least one acute sign: loss of consciousness, post-traumatic amnesia, disorientation, or focal findings.
• The neurocognitive deficits must appear immediately after the injury or immediately after recovery of consciousness, not emerge months later.
• Deficits must persist past the acute post-injury period, which DSM-5-TR anchors at beyond one week following the event.
• Major versus mild turns on independence: major means the person requires assistance with instrumental activities of daily living.
• Severity of the brain injury and severity of the resulting neurocognitive disorder are separate judgments and need not match.

Neurobiology

• Diffuse axonal injury from rotational shear disrupts white matter tracts, seen as reduced fractional anisotropy on diffusion tensor imaging.
• A secondary injury cascade unfolds over hours to days: glutamate excitotoxicity, calcium influx, mitochondrial failure, inflammation, and oxidative stress.
• Frontal and anterior temporal poles bear the brunt of contusion against bony ridges, which explains the executive and behavioral phenotype.
• Catecholaminergic signaling is disrupted, which is the rationale for methylphenidate and amantadine improving arousal and processing speed.
• APOE e4 carriers show poorer recovery, and repetitive head impacts are linked to chronic traumatic encephalopathy tau pathology at autopsy.
• Post-traumatic epilepsy, pituitary dysfunction with hypogonadism or hypothyroidism, and sleep apnea are common, treatable, and routinely missed.

Psychology

• Impaired self-awareness is neurologic rather than denial, and it undermines safety judgment and rehabilitation adherence more than any single test score.
• Premorbid factors including prior injuries, psychiatric history, and litigation or compensation context strongly shape persistent symptom reporting.
• Expectation shapes outcome: beliefs about permanent brain damage and misattribution of ordinary symptoms maintain post-concussive complaints.
• Grief over the pre-injury self drives depression, which affects roughly half of patients within the first year after moderate to severe injury.
• Fatigue combined with disinhibition strains family systems, and caregiver-reported behavior change predicts return-to-work failure better than imaging.

Differential & comorbidity

• PTSD and TBI overlap heavily in veterans and share insomnia, irritability, and concentration failure, so both are treated rather than ranked.
• Depression, substance use, chronic pain, and sleep apnea each independently degrade cognition and must be treated before deficits are attributed to the injury.
• Suicide risk is roughly doubled after traumatic brain injury, and impulsivity with disinhibition converts ideation into action rapidly.
• Assess performance validity in medicolegal contexts, which is standard practice in traumatic brain injury neuropsychological evaluation.
• Consider post-traumatic hydrocephalus, chronic subdural hematoma, seizures, and endocrine failure when decline is late, sudden, or stepwise.

Pharmacologic treatment

• No agent is approved for post-traumatic cognition, so treat discrete targets such as attention, mood, headache, and sleep with the fewest drugs possible.
• Amantadine 100-200 mg twice daily accelerates functional recovery in disorders of consciousness and is the best-supported cognitive agent.
• Methylphenidate 5-20 mg twice daily improves processing speed and attention; monitor blood pressure, appetite, sleep, and irritability.
• Sertraline or escitalopram are first-line for post-injury depression, started low because this population is sensitive to side effects.
• Avoid benzodiazepines, anticholinergics, and typical antipsychotics; antiseizure prophylaxis beyond 7 days does not prevent post-traumatic epilepsy.

Psychotherapy

• Cognitive rehabilitation using metacognitive strategy training carries the strongest evidence for executive dysfunction and attention deficits.
• Early education and reassurance after mild injury reduces persistent post-concussive symptoms and is the single best-supported intervention.
• CBT adapted for cognitive load, using written summaries, repetition, and shorter sessions, treats post-injury depression, anxiety, and insomnia.
• Applied behavior analysis with antecedent management is preferred over medication for aggression and disinhibition after brain injury.
• Family therapy and caregiver training address role change, supervision needs, and unrealistic recovery timelines that fuel conflict.

Adjunct options

• Graded return to activity within 24 to 48 hours after concussion outperforms strict rest, which prolongs symptom duration.
• Use external compensatory aids relentlessly: smartphone alarms, written checklists, one shared calendar, and highly structured daily routines.
• Vestibular and oculomotor rehabilitation plus cervical physical therapy resolve much of the dizziness and headache burden after concussion.
• Screen for post-traumatic hypopituitarism at 3 to 6 months and evaluate for sleep apnea, both frequently missed drivers of persistent fatigue.
• Track outcomes with the MoCA, the Rivermead Post-Concussion Questionnaire, and return-to-work status rather than repeat neuroimaging.

Clinical pearls

• Post-traumatic amnesia length predicts outcome better than GCS or CT findings.
• Strict rest after concussion prolongs recovery; graded activity by 48 hours is better.
• In veterans, assume PTSD and TBI coexist and treat both rather than picking one.