Published: Thu, April 12, 2018
Medicine | By Rogelio Lindsey

Brain injury in teenagers may increase the risk of Alzheimer's disease: Lancet

Brain injury in teenagers may increase the risk of Alzheimer's disease: Lancet

Traumatic brain injury (TBI) was found to increase the risk of Alzheimer's and other forms of dementia by 24 per cent over a period of 36 years.

After one of the largest ever investigations into the link between traumatic brain injury (TBI) and cognitive decline in later life, Danish and U.S. researchers concluded that the younger a person was when sustaining a head injury, the higher the risk of developing Alzheimer's and other forms of dementia.

Traumatic brain injury caused by an accident or a blow to the head increases the risk of dementia according to a recently published study.

"Our findings do not suggest that everyone who suffers a traumatic brain injury will go on to develop dementia later in life", Fann said. The study also examined the impact of sustaining multiple separate brain injuries and the likelihood of subsequently developing dementia. "Making major decisions about brain injured patients rely on quick assessments and the new method gives us rapid insights into the patient's condition". According to the study authors, more than 50 million people every year experience a traumatic brain injury. Leading causes of TBI include falls, traffic crashes and assaults. Those affected should avoid certain behaviors, researchers suggest.

Fann said his team's research is able to provide better evidence of a link because of the large sample size, though the study is limited because it draws on patients from a single country that's relatively ethnically homogenous.

For their study, the researchers evaluated data from the Danish patient registry of almost three million people. For example, a person over 50 who suffered one TBI had a 22% increased risk of developing dementia, while someone who suffered four TBIs had a 61% increased risk.

Despite the size of the studies, they won't settle scientific questions - or social debate - about brain injuries from sports, war, auto crashes or domestic violence. However, they were not able to account for some potential confounders such as education, high blood pressure, smoking, and obesity, which could result in the association between TBI and dementia being over or underestimated. The researchers found that 4.3 percent of participants with dementia had at least one mild TBI, compared with 4 percent of those without dementia.

"What surprised us was that even a single mild TBI was associated with a significantly higher risk of dementia", lead author Jesse Fann, a professor of psychiatry and behavioral sciences at the University of Washington School of Medicine, said in a statement.

Among men and women with TBI histories, men had slightly higher rate of developing dementia (30 percent vs. 19 percent). TBI correlated with elevated dementia risk compared to individuals with a non-TBI fracture not involving the skull or spine (hazard ratio, 1.29).

"Shedding light on risk factors for dementia is one of the most important tasks in health research".

"However, it's important to emphasize that although the relative risk of dementia is increased after traumatic brain injury, the absolute risk increase is low", Fann noted in a journal news release.

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