Researchers from the University of California, San Francisco, found that older adults, aged 55 and above, are at higher risk of developing dementia after enduring a traumatic brain injury (TBI). The study looked at the data of 164,661 people who were brought to the hospital due to TBI and non-TBI body trauma (NTT) or fractures excluding the head and neck. About 32 percent (or 51,799 patients) were identified to have a TBI.
However, the researchers of this latest study – including Dr. Raquel C. Gardner of the University of California-San Francisco – note that other studies have not found a link between TBI and dementia, but such studies have been subject to many limitations. “Even among studies that report a positive association between TBI and dementia, marked variability exists in the magnitude of reported risk,” the researchers add, “which may be due to differences in TBI severity, age of patients, and follow-up period – with some being as short as 2 years – among studies.”
“While many studies have shown that traumatic brain injuries in early life increase the chance of getting dementia, it has been harder to establish whether late-life injuries also increase the chance of getting dementia,” she said. “This is a very important question because the highest rates of traumatic brain injury in this country are in older adults.”
The researchers note that few studies assessing the link between TBI and dementia have used patients with NTT as controls. Doing so strengthens the study results, they say, as it mitigates the possibility of reverse causality. Patients were followed-up for an average of 5.7 years and had no signs of dementia at study baseline.
The team concluded that one incident of brain injury increases one’s risk of developing dementia by 26 percent; more than one doubles the risk. However, some experts were not convinced of the findings because of the data used in the study.
“There was not a non trauma control group included, which may have answered the question of whether NTT (i.e. body trauma itself) raised the risk of dementia significantly above age-equivalent controls without non brain trauma (perhaps from inflammation or other complications),” Dr. Steven T. DeKosky of the University of Pittsburgh School of Medicine, said.
To conduct the study researchers examined all in all 52,000 patients from emergency rooms in California between 2005 and 2011. Each patient suffered from some type of traumatic injury and were over the age of 55. Six percent of patients with non-brain related injuries developed dementia later on. However, 8 percent of patients with brain injuries developed the disease.