The features of persisting major or mild NCD due to TBI will vary by age, specifics of the injury, and cofactors. Persisting TBI-related impairment in an infant or child may be re- ﬂected in delays in reaching developmental milestones (e.g., language acquisition), worse academic performance, and possibly impaired social development. Among older teenag- ers and adults, persisting symptoms may include various neurocognitive deficits, irrita- bility, hypersensitivity to light and sound, easy fatigability, and mood changes, including depression, anxiety, hostility, or apathy. In older individuals with depleted cognitive re- serve, mild TBI is more likely to result in incomplete recoveries.
Risk factors for traumatic brain injury. Traumatic brain injury rates vary by age, with the highest prevalence among individuals younger than 4 years, older adolescents, and in- dividuals older than 65 years. Falls are the most common cause of TBI, with motor vehicle accidents being second. Sports concussions are frequent causes of TBI in older children, teenagers, and young adults.
Risk factors for neurocognitive disorder after traumatic brain injury. Repeated con- cussions can lead to persistent NCD and neuropathological evidence of traumatic enceph- alopathy. Co-occurring intoxication with a substance may increase the severity of a TBI from a motor vehicle accident, but whether intoxication at the time of injury worsens neu- rocognitive outcome is unknown.
Course modifiers. Mild TBI generally resolves within a few weeks to months, although res- olution may be delayed or incomplete in the context of repeated TBI. Worse outcome from moderate to severe TBI is associated with older age (older than 40 years) and initial clinical pa- rameters, such as low Glasgow Coma Scale score; worse motor function; pupillary nonreac- tivity; and computed tomography (CT) evidence of brain injury (e.g., petechial hemorrhages, subarachnoid hemorrhage, midline shift, obliteration of third ventricle).
Beyond neuropsychological testing, CT scanning may reveal petechial hemorrhages, subarachnoid hemorrhage, or evidence of contusion. Magnetic resonance image scanning may also reveal hyperintensities suggestive of microhemorrhages.
Functionai Consequences of Major or Miid
Neurocognitive Disorder Due to Traumatic Brain Injury
With mild NCD due to TBI, individuals may report reduced cognitive efficiency, difficulty concentrating, and lessened ability to perform usual activities. With major NCD due to TBI, an individual may have difficulty in independent living and self—care. Prominent neuromotor features, such as severe incoordination, ataxia, and motor slowing, may be present in major
NCD due to TBI and may add to functional difficulties. Individuals with TBI histories report more depressive symptoms, and these can amplify cognitive complaints and worsen func- tional outcome. Additionally, loss of emotional control, including aggressive or inappropriate affect and apathy, may be present after more severe TBI with greater neurocognitive impair- ment. These features may compound difficulties with independent living and self-care.
In some instances, severity of neurocognitive symptoms may appear to be inconsistent with the severity of the TBI. After previously undetected neurological complications (e.g., chronic hematoma) are excluded, the possibility of diagnoses such as somatic symptom disorder or factitious disorder need to be considered. Posttraumatic stress disorder (PTSD) can co-occur with the NCD and have overlapping symptoms (e.g., difficulty concentrat- ing, depressed mood, aggressive behavioral disinhibition).
Among individuals with substance use disorders, the neurocognitive effects of the sub- stance contribute to or compound the TBI-associated neurocognitive change. Some symp- toms associated with TBI may overlap with symptoms found in cases of PTSD, and the two disorders may co-occur, especially in military populations.