Traumatic brain injury is associated with increased risk of dementia diagnosis.
Traumatic brain injury (TBI) is a leading cause of morbidity and mortality worldwide, particularly among populations who are older than 45 years. Among other neurological deficits and disabilities, research suggests that TBI is also associated with an increased risk of developing dementia later in life. Dementia is a neurodegenerative disease that can drastically reduce an individual’s quality of life. Although the implications of dementia are serious and merit extensive research, the relationship between TBI and dementia remains unclear.
To address this gap, a group of researchers in Sweden conducted a largescale study of Swedish men and women older than fifty years. They collected data on these participants’ demographic information, medical histories, and disability pensions. To account for possible familial similarities in the likelihood of developing dementia, the researchers also studied sibling pairs, whose shared genetic makeup can provide information about the role of familial factors. After analyzing data from hundreds of thousands of participants, the researchers found that:
- In the first year after TBI, the risk of developing dementia increased by four to six times.
- The risk of developing dementia steadily decreased after the first year following TBI. However, even 30 years after injury, those who experienced TBI were still significantly more likely to develop dementia.
- Risk of dementia was higher for those whose TBI was severe and for those who experienced multiple TBIs of any severity level.
- The sibling pairings, which served as a genetic control group, generally confirmed these findings.
Dementia is a serious neurodegenerative disease with potentially serious, long-term consequences, such as impaired function and risk of fatal falls. Importantly, researchers have identified a strong association between a history of TBI – particularly severe TBI or multiple TBIs over time – and an increased risk of developing dementia, even decades after sustaining the initial injury. When diagnosing and treating those with dementia, clinicians are advised to consider any history of head trauma over the entire lifespan.
Nordström A & Nordström P. Traumatic brain injury and the risk of dementia diagnosis: A nationwide study. PLOS Medicine. (January 2018).