280 Trauma- and Stressor-Related Disorders
psychotic features; delirium; substance/medication-induced disorders; and psychotic dis-
orders due to another medical condition. 
Traumatic brain injury. When a brain injury occurs in the context of a traumatic event (e.g.,
traumatic accident, bomb blast, acceleration/d eceleration trauma), symptoms of PTSD may
appear. An event causing head trauma may also  constitute a psychological traumatic event,
and tramautic brain injury (TBI)–related neurocognitive symptoms are not mutually exclusive
and may occur concurrently. Sy mptoms previously termed postconcussive  (e.g., headaches,
dizziness, sensitivity to light or  sound, irritability, concentration deficits) can occur in brain-
injured and non-brain-injured populations, in cluding individuals with PTSD. Because symp-
toms of PTSD and TBI-related neurocognitive symptoms can overlap, a differential diagnosis
between PTSD and neurocognitive disorder sy mptoms attributable to TBI may be possible
based on the presence of symptoms that are di stinctive to each presentation. Whereas reexpe-
riencing and avoidance are characteristic of PTSD  and not the effects of TBI, persistent disori-
entation and confusion are more specific to TBI (neurocognitive effects) than to PTSD.
Comorbidity
Individuals with PTSD are 80% more likely than those without PTSD to have symptoms
that meet diagnostic criteria for at least one other mental disorder (e.g., depressive, bipo-
lar, anxiety, or substance use disorders). Comorbid substance use disorder and conduct
disorder are more common among males than  among females. Among U.S. military per-
sonnel and combat veterans who have been de ployed to recent wars  in Afghanistan and