Scientists have long believed that a single traumatic brain injury (TBI) earlier in life may contribute to problems with memory, thinking and depression later in life. In most previous studies, however, research failed to examine the possible role of having a history of exposure to repetitive head impacts, including those leading to “subconcussive” injuries, in these later-life problems. In the largest study of its kind, an association has been found in living patients exposed to repetitive head impacts and difficulties with cognitive functioning and depression years or decades later.
Scientists from the Boston University (BU) Alzheimer’s Disease and Chronic Traumatic Encephalopathy (CTE) Centers, the University of California, San Francisco (UCSF), and San Francisco VA Healthcare System teamed up to analyze the records of 13,323 individuals age 40 and older (average age 62) who participate in the internet-based Brain Health Registry. Of those, 725 or 5 percent of participants reported exposure to previous repetitive head impacts through contact sports, abuse or military service. In addition to repetitive head impact history, the scientists also examined the effects of having a TBI with and without loss of consciousness.
Along with self-report questionnaires of repetitive head impact and TBI history, participants completed measures of depressive symptoms and computerized cognitive tests. The findings, published in the journal Neurology, reveal that participants with a history of both repetitive head impacts and TBI reported greater depression symptoms than those who did not have such history. In addition, when repetitive head impacts and TBI were examined separately, a history of repetitive head impacts had the strongest effect on later-life symptoms of depression. The findings were independent of age, sex, racial identity and education level.