People who have suffered a traumatic brain injury (TBI) have a significantly higher risk of dementia than those who have no history of brain injury, according to one of the largest studies of its kind to date.
In the study, published April 10 in The Lancet Psychiatry, researchers from the University of Washington (UW) and Aarhus University Hospital in Denmark reviewed nearly 2.8 million patient records. They found people with a history of TBI had a 24 percent higher risk of dementia than those who had no history.
“What surprised us was that even a single mild TBI was associated with a significantly higher risk of dementia,” said lead author Dr. Jesse Fann, a professor of psychiatry and behavioral sciences at UW and adjunct professor of epidemiology at the University of Washington School of Public Health. “The relationship between the number of TBIs and risk of dementia was very clear. Similarly, a single severe brain injury seems to have twice the risk associated with dementia as a single mild TBI.”
According to the study, a single TBI characterized as “severe” increased the risk of developing dementia by 35 percent. A single “mild” TBI or concussion increased the risk by 17 percent. What’s more, researchers found that people who had a brain injury in their twenties were 60 percent more likely to develop dementia in their fifties.
Dementia affects 47 million people globally, a number expected to double in the next 20 years. Every year, more than 50 million people experience a TBI, which occurs when an external force disrupts the brain’s normal function. Leading causes include falls, motor vehicle accidents and assaults.
It’s important to recognize that most people who sustain a single concussion do not develop dementia, according to Dr. Fann. He also clarified that the findings do not suggest every person who sustains a severe TBI will develop dementia later in life. However, findings might lead people with TBI histories to change behaviors toward other potential risk factors for dementia, such as limiting alcohol and tobacco use, engaging in regular exercise, preventing obesity, and treating hypertension and diabetes.
More research is needed to understand who is at greatest risk of dementia and what other factors contribute to the risk. Researchers call for heightened efforts to prevent TBI, especially among younger people, and say strategies are needed to ameliorate the risk and impact of dementia associated with TBI.