Head injury in early adulthood and the lifetime risk of depression.

BACKGROUND: Depressive symptoms are common and can be debilitating in the months after head injury. Head injury can also have long-term cognitive effects, but little is known about the long-term risk of depression associated with head injury. We investigated the lifetime rates of depressive illness 50 years after closed head injury.
METHODS: Participants were male World War II veterans who served during 1944-1945 and were hospitalized at that time for a head injury, pneumonia, or laceration, puncture, or incision wounds. We used military medical records to establish the presence and severity of closed head injuries. Veterans with (n = 520) and without (n = 1198) head injuries were interviewed in 1996-1997 for their lifetime history of depressive illness. Men with dementia were excluded.
RESULTS: Veterans with head injury were more likely to report major depression in subsequent years and were more often currently depressed. Using logistic regression and controlling for age and education, the lifetime prevalence of major depression in the head injured group was 18.5% vs 13.4% in those with no head injury (odds ratio = 1.54, 95% confidence interval = 1.17-2.04). Current major depression was detected in 11.2% of the veterans with head injuries vs 8.5% of those without head injury (odds ratio = 1.63, 95% confidence interval = 1.07-2.50). This increase in depression could not be explained by a history of myocardial infarction, a history of cerebrovascular accident, or history of alcohol abuse. The lifetime risk of depression increased with severity of the head injury.
CONCLUSION: The risk of depression remains elevated for decades following head injury and seems to be highest in those who have had a severe head injury.