Traumatic Brain Injury Associated With Increased Risk for Dementia

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Researchers in Denmark conducted a nationwide observational cohort study with 2.8 million adults at risk for dementia for a total follow-up period of 27.6 million person-years between 1999 and 2013.
Researchers in Denmark conducted a nationwide observational cohort study with 2.8 million adults at risk for dementia for a total follow-up period of 27.6 million person-years between 1999 and 2013.

Research published in The Lancet found that traumatic brain injury (TBI) was associated with an increased risk for dementia compared with no history of TBI or with non-TBI trauma.

Researchers in Denmark conducted a nationwide observational cohort study with 2.8 million adults at risk for dementia for a total follow-up period of 27.6 million person-years between 1999 and 2013. The study used 3 pre-specified models for the analyses; the first model adjusted for sociodemographic factors, the second added medical and neurologic comorbidities, and the third added psychiatric comorbidities.

Of the total cohort, 132,093 patients (4.7%) had an incidence of at least 1 TBI between 1977 and 2013, and 126,734 (4.5%) individuals older than 50 developed dementia during the study follow-up period. Of the patients with dementia, 6724 (5.3%) sustained at least 1 TBI during the study period.

In the first analytical model, the risk for dementia was higher in patients with a history of TBI compared with patients without (hazard ratio [HR] 1.58; 95% CI, 1.54-1.62); after adjusting for medical, neurologic, and psychiatric comorbidities, the risk decreased but remained high (HR 1.24; 95% CI, 1.21-1.27). The risk for dementia was highest during the first 6 months following TBI incidence (HR 4.06; 95% CI, 3.79-4.34), and decreased gradually to an HR of 1.17 (95% CI, 1.13-1.21) at more than 14 years post-TBI.

The risk for dementia also increased with an increased number of TBIs; patients with ≥5 TBIs had a significantly higher risk (HR 2.83; 95% CI 2.14-3.75) than patients with 1 TBI (HR 1.22; 95% CI 1.19-1.25). TBI was associated with a higher risk for dementia in patients with TBI (HR 1.29; 95% CI 1.26-1.33) compared with patients with a non-TBI fracture not involving the skull or spine. Men with a history of TBI were at a slightly higher risk for dementia than women with the same history. In addition, younger age at TBI incidence was associated with higher hazard ratios for dementia when stratified by time since TBI.

Researchers noted that data collected in Denmark may not reflect global trends, given the country's ethnically homogenous population and socialized healthcare system. However, these data support the importance of TBI preventative measures and proper management strategies for subsequent dementia.

Reference

Fann JR, Ribe AR, Pedersen 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]. The Lancet. doi:10.1016/S2215-0366(18)30065-8

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