Study Links Number, Severity of Brain Injuries to Dementia

(CN) – New research in the journal Lancet Psychiatry offers more evidence on the link between traumatic brain injuries and dementia for older adults.

A section of a preserved human brain is displayed on Oct. 7, 2003, at the Museum of Neuroanatomy at the University at Buffalo, in Buffalo, N.Y. A study published on April 10, 2018, offers more evidence of a link between traumatic brain injuries and dementia later in life, with repeated injuries and severe ones posing the greatest danger. (AP Photo/David Duprey)

Published on Tuesday, the study led by Jesse Fan of the University of Washington School of Medicine in Seattle capitalized on features of the national health system in Denmark that allow researchers to explore connections in health records.

Pulling data on 2.79 million people at risk of dementia, the researchers looked for a subset of people born in Denmark who were living in the country on Jan 1, 1995, and who were at least 50 years old when approached for follow-up information between 1999 and 2013.

The results showed that fewer than 5 percent of people who suffered a traumatic brain injury developed dementia, but that the risk of dementia is highest in the first six months after a severe brain injury and increases along with the number of events.

Abbreviating traumatic brain injury, the researchers found that, as compared with individuals who suffered a non-TBI fracture not involving the skull or spine, “TBI was associated with a higher risk of dementia.”

The specific risk of Alzheimer’s disease was also higher after a TBI event, according to the report.

Researchers found that age plays a factor: “the younger a person was when sustaining a TBI, the higher the HRs [hazard ratios] for dementia when stratified by time since TBI.”

Of the population studied, 132,093 individuals (4·7 percent) had at least one TBI during 1977–2013, and 126,734 (4·5 percent) had incident dementia during 1999–2013.

Researchers obtained their TBI data from the Danish National Patient Register, while information on dementia involved a combination of data from the National Patient Register, the Danish Psychiatric Central Register and the Danish National Prescription Registry.

For each of three survival analyses that the researchers used to determine the long-term risk of dementia after TBI, three prespecified models were used: different time periods since the TBI, multiple TBIs and sex.

“The first model adjusted for sociodemographic factors, the second model added medical and neurological comorbidities, and the third added psychiatric comorbidities,” according to the report.

Funded by the Lundbeck Foundation, the report closes with a call for increased efforts to prevent TBI and to identify strategies that ameliorate the risk and impact of subsequent dementia.

A report from the Associated Press notes that the Danish study aligns with findings from a study of 3.3 million people in Sweden earlier this year.

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