People with a history of head injury may have an increased lifetime risk of depression, according to a recent psychiatric study at the Medical Center.
Duke researchers found that the lifetime prevalence of major depression in a group of 1,718 veterans injured during World War II was 18.5 percent for those who suffered head injuries compared to 13.4 percent for those hospitalized for other reasons.
Researchers interviewed veterans more than 50 years after the war to determine if they had developed clinical depression. World War II veterans are optimal subjects because a long time has elapsed since their injuries, and the federal government provided the participants' medical records, said Tracey Holsinger, consulting associate in the Department of Psychiatry and Behavioral Sciences.
"The greatest risk of depression was found in those with the most severe head injuries," said Brenda Plassman, assistant research professor of psychiatry.
Additionally, older participants in the study had a higher risk for depression after head injuries. In typical populations, elderly people have lowered risk for depression. "In our sample, the lifetime history of depression increased as the men got older," Plassman said.
Based on previous research linking head trauma to a higher risk of dementia, researchers suspected that there may also be other long-term effects of head injury on the brain.
"There are several factors that pointed us to depression," Plassman said. "First, we know that rates of depression are quite high in the short-term following head injury. Second, we also know that depression is a major public health concern in the older population. Third, there are some biologically plausible explanations for development of depression after head injury."
Pinpointing the specific cause of depression following head trauma is difficult because an individual's unhappiness may be attributed to psychological, physical or others factors.
Holsinger said it is also difficult to determine the biological mechanism by which a head injury may affect an individual's risk for depression. When a person suffers head trauma, destruction of neurons or an inflammatory response may later induce depression. An increase in brain chemicals called cytokines occurs with both depression and an inflammatory response to head injury, Holsinger noted.
The researchers did not include a quality-of-life measure as part of the study to determine if the men's experiences, rather than their injuries, may have helped to cultivate depression, but the study did exclude participants who had histories of vascular problems, alcohol abuse, dementia or other disabling conditions. "[The participants] are presumably productive people," Holsinger said.
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