WASHINGTON — Greater intellectual resources may, according to a new study of Vietnam veterans, help buffer soldiers from developing post-traumatic stress disorder (PTSD) after combat. These findings appear in the January issue of Neuropsychology, published by the American Psychological Association (APA).
The same study confirmed that Vietnam veterans with PTSD, independently of intellectual resources, have more problems in attention, working memory and new learning than veterans without PTSD -- an association also found in Gulf War veterans.
PTSD, first diagnosed as “shell shock” during World War I, is a distressing, sometimes disabling anxiety disorder precipitated by exposure to extreme psychological trauma, such as combat, torture, abuse or natural disaster. It is characterized by re-experiencing of the trauma (such as nightmares and intrusive thoughts), behavioral avoidance of reminders of that trauma, emotional numbing, and symptoms of increased arousal (such as sleep disturbance and exaggerated startle response). According to the National Vietnam Veterans Readjustment Study, 30.9 percent of male Vietnam veterans and 26.9 percent of female Vietnam veterans met the criteria for lifetime PTSD (at any point in their lives, but not necessarily at the time of testing). In the general population, the lifetime prevalence of PTSD has been estimated at anywhere between one and 14 percent, and in one study as high as 23.6 percent.
Jennifer J. Vasterling, Ph.D., of the Veterans Affairs Medical Center in New Orleans, Tulane University School of Medicine and Louisiana State University School of Medicine, led a six-person team that compared the neurocognitive performance and pre-Vietnam intellectual resources of 26 combat veterans with posttraumatic stress disorder (PTSD) and 21 combat veterans without mental disorders. In addition, they measured recorded level of combat exposure and education completed prior to Vietnam service. For PTSD veterans, they also assessed the severity of the disorder.
Vasterling et al. found that although extent of combat in Vietnam was the most important predictor of PTSD severity, estimated premilitary IQ appeared to help to buffer the vets from developing PTSD. In other words, veterans with greater pre-combat intellectual resources were significantly less likely to have PTSD. In veterans that developed PTSD, greater intellectual resources were associated with less-severe symptoms.
The authors speculate that intellectual sophistication may protect against psychopathology in a variety of mechanisms. For example, greater verbal skills may help soldiers, says Vasterling, to “’talk out’ and make sense of their experience.” Language can help them to mentally “frame” overwhelming events and to process their extreme feelings and memories. Verbal skills may also help them establish more elaborate networks for social support.
Combat veterans may also have resisted PTSD by dint of greater educational attainment, occupational achievement and other higher socioeconomic levels that also buffer stress impact. Also, the authors suggest that greater intellectual resources prior to combat may reflect a hardier, more stress-resistant brain.
In other significant results, Vietnam vets with PTSD diagnoses performed less proficiently on tasks assessing sustained attention, working memory, and initial registration of verbal information compared with Vietnam vets without the PTSD diagnosis. This study replicated similar findings on attention, learning and memory in Gulf War veterans, an echo that enables scientists to generalize findings about traumatic stress-related cognitive problems across veteran populations with different war experiences, socio-demographic characteristics and time-course of the disorder.
The specific cognitive problems were not related to lower overall intellectual functioning; in other words, veterans with PTSD had the deficits regardless of their pre-combat intellectual resources. With this finding, the authors conclude that the cognitive inefficiency of PTSD does not result from an overall dampening of intellectual ability.
These findings are consistent with current neurobiological models of post-traumatic stress disorder, which envision extreme stress as affecting specific brain areas as well as arousal mechanisms. Deficits on specific attention and anterograde memory tasks (which assess the ability to form and retain new memories) suggest abnormalities in the brain’s frontal-limbic circuits. Weaknesses involving sustained attention, working memory and new learning may be attributed to disordered arousal and dysfunction of the prefrontal cortex, and possibly, to a lesser extent, the hippocampus.
“These cognitive problems are relatively mild when compared to disorders with frank neurological pathology, such as Alzheimer’s disease,” says Vasterling. “However, they do trouble the veterans, who state that they interfere with daily life -- especially their poor concentration.” Based on the findings, Vasterling suggests that “preventive training in a broad range of coping skills would be beneficial. In addition, cognitive rehabilitation can be structured to capitalize on people’s internal strengths -- such as the ability to verbalize and write things down -- to help them circumvent their weaknesses, such as difficulty concentrating or remembering. Rehabilitation can also employ external devices, such as calendars and notepads.”
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