PTSD Not Most Common Disorder That Develops After Trauma

A large Australian study adds weight to the view that depression and anxiety are more likely psychiatric outcomes than posttraumatic stress disorder (PTSD) in the year following trauma.

The researchers also reported that patients with psychiatric disorders assessed at 12 months had more functional impairment, regardless of whether they had sustained a mild traumatic brain injury (TBI), and that mild TBI alone did not lead to greater functional impairment.

Overall, 23 percent of the 817 patients studied developed a new psychiatric disorder by the time of a 12-month assessment, wrote Richard Bryant, Ph.D., of the School of Psychology at Australia's University of New South Wales, and colleagues in the March American Journal of Psychiatry.

“A novel finding was that PTSD was not the most prevalent psychiatric disorder after traumatic injury, and when PTSD did occur, it typically occurred in the presence of another disorder,” they said.

Initially, the researchers assessed 1,084 patients while in the hospital and assessed 817 at 12 months. Most were hurt in auto accidents, but some were victims of assault or traumatic falls. There was no non-trauma-exposed control group.

Depression (9 percent), generalized anxiety disorder (9 percent), PTSD (6 percent), and agoraphobia (6 percent) were the most common new diagnoses. These rates were higher than those recorded in the general Australian population.

PTSD tended to co-occur with other psychiatric disorders. Only 9 percent of subjects with PTSD had no comorbid disorders.

“This finding challenges the notion that PTSD is always the primary psychiatric disorder after trauma,” said Bryant and colleagues. “[I]t appears that a broader range of disorders affect people after traumatic injury.”

They also noted that prevalence rates of the psychiatric disorders affecting their subjects remained nearly the same at 12 months as they were at three months.

The researchers excluded from the study patients with moderate to severe traumatic brain injury.

Those with mild TBI developed PTSD, panic disorder, agoraphobia, or social phobia twice as often as those with no TBI. Major depression and generalized anxiety disorder were unrelated to mild TBI in their analysis.

Mild TBI alone did not raise the odds ratio for physical or psychological impairment, but the combination of mild TBI and either PTSD, depression, anxiety, or any psychiatric disorder did so significantly. Having any psychiatric disorder without mild TBI also raised the odds of impairment significantly.

Bryant and colleagues suggested that damage to the forebrain, common in mild TBI, may have affected regulation of the amygdala or hippocampus or have compromised the neural networks that regulate emotion.

Only one-third of study patients who recorded a psychiatric disorder sought mental health care in the month prior to the 12-month assessment, although the researchers did not ask if they had received treatment earlier.

The study's conclusions regarding mild TBI enter into another debate, one over the relative roles of brain injury and traumatic experience.

“Clinically, if a person has a mild brain injury after trauma and has PTSD or social phobia, it happens not just from the injury but from the trauma,” said Jonathan Silver, M.D., a clinical professor of psychiatry at New York University School of Medicine, who was not involved in the study. “Having [a mild] TBI may increase your chances for PTSD, but the accident alone increases your risk of getting depression or anxiety.”

Having a psychiatric disorder such as depression or anxiety on top of a brain injury often leads to worse neuropsychiatric outcomes, he said.

Bryant's study may even underestimate the scope of the problem, since other research has shown that emergency-room personnel miss half of all mild TBIs because they don't have the time or resources to screen for them, added Silver.

“Unfortunately, there is also little research on whether treating psychiatric sequelae improves TBI symptoms,” he said.

An abstract of “The Psychiatric Sequelae of Traumatic Injury” is posted at <http://ajp.psychiatryonline.org/cgi/content/abstract/167/3/312>.