TBI Raises Long-Term Dementia Risk

Traumatic brain injury (TBI) raises the risk for dementia in the long-term compared with individuals with no history of TBI and those with non-TBI trauma, according to new research.

Although TBI has long been associated with dementia, few large-scale studies with long follow-up have been performed. To provide more information on the long-term effects of TBI, researchers studied a large cohort of 2,794,852 people in Denmark (27,632,020 person-years) with a risk for dementia.

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Data on TBI and dementia was obtained from national registries. Follow-up lasted from 1999 to 2013. All patients included in the study were living in Denmark on January 1, 1995, and were aged at least 50 years at some point throughout follow-up.

Survival analysis was performed to ascertain the long-term risk of dementia after TBI using 3 prespecified models: different time periods since TBI, multiple TBIs, and sex. Each model was adjusted for various factors.

A total of 132,093 participants (4.7%) had at least 1 TBI between 1977 and 2013, and 126,734 (4.5%) had incident dementia between 1999 and 2013. Ultimately, the researchers found that the fully adjusted risk of all-cause dementia (hazard ratio [HR] 1.24) and the specific risk of Alzheimer disease (HR 1.16) were higher in participants with a history of TBI 1.24) vs those without a history of TBI.

The risk for dementia was found to be highest within the first 6 months following TBI (HR 4.06) and among participants with a higher number of events (1.22). Furthermore, the association between TBI and higher risk of dementia (HR 1.29) was stronger in participants with TBI vs those with a non-TBI fracture not involving the skull or spine.

The researchers noted that younger age at TBI was associated with higher HRs for dementia when stratified by time since TBI.

“TBI was associated with an increased risk of dementia both compared with people without a history of TBI and with people with non-TBI trauma,” the researchers concluded. “Greater efforts to prevent TBI and identify strategies to ameliorate the risk and impact of subsequent dementia are needed.”

—Christina Vogt


Fann JR, Riisgaard Ribe A, Pederson HS, et al. Long-term risk of dementia among people with traumatic brain injury in Denmark: a population-based observational cohort study [Published online April 10, 2018]. Lancet Psychiatry.