Differential Diagnosis
In some instances, severity of neurocognitive symptoms ma y appear to be inconsistent
with the severity of the TBI. After previously  undetected neurologic al 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 overlappi ng symptoms (e.g., difficulty concentrat-
ing, depressed mood, aggressiv e behavioral disinhibition).
Comorbidity
Among individuals with substa nce use disorders, the neurocognitive effects of the sub-
stance contribute to or compound the TBI-as sociated neurocognitive change. Some symp-
toms associated with TBI may overlap with sy mptoms found in cases of PTSD, and the two
disorders may co-occur, especia lly in military populations. 
Substance/Medication-Induced
 Major or Mild Neurocognitive Disorder
Diagnostic Criteria
A. The criteria are met for major or mild neurocognitive disorder.
B. The neurocognitive impairments do not occur exclusively during the course of a delir-
ium and persist beyond the usual duration of intoxication and acute withdrawal.
C. The involved substance or medication and duration and extent of use are capable of
producing the neurocognitive impairment.
D. The temporal course of the neurocognitive deficits is consistent with the timing of sub-
stance or medication use and abstinence (e.g., the deficits remain stable or improve
after a period of abstinence).