A recent study on twins has revealed a deeper understanding of the traumatic brain injury and dementia link. Sometimes, cognitive decline shows up decades later.
The research, led by scientists from Duke Health and published on September 6 in the online edition of Neurology, the medical journal of the American Academy of Neurology, focused on 8,662 male World War II veteran twins with an average age of 67.
At the study's onset, the participants reported whether they had experienced a concussion or traumatic brain injury (TBI) in their lifetime. They also underwent initial cognitive assessments and again up to three more times for 12 years.
Among the participants, 25% reported experiencing one or more TBIs at some point in their lifetime.
After adjusting for factors that could impact cognitive skills, the team found that a twin who experienced a concussion was more likely to have lower cognitive test scores by the age of 70 than a sibling without a history of TBI. This was particularly true if their concussion involved loss of consciousness or occurred after 24 years of age.
In addition, twins who had experienced traumatic brain injuries (TBIs) with loss of consciousness, multiple TBIs, or concussions after age 24 were also at a higher risk of experiencing accelerated cognitive decline than those without any history of TBI.
For example, the cognitive abilities of participants who had experienced a traumatic brain injury after age 24 deteriorated 0.05 points faster per year.
In a Duke Health news release, lead author Marianne Chanti-Ketterl, Ph.D., an assistant professor with Duke's Department of Psychiatry & Behavioral Sciences, said, "This study highlights the importance of treating concussions and TBIs appropriately when they occur. Our knowledge and understanding of these injuries has greatly increased. This study demonstrates the importance of treatments for head injuries and the need to minimize or prevent these injuries."
Still, because participants self-reported TBIs, incidences could have been missed or over-reported, which could have impacted the results.
However, Chanti-Ketterl notes that because the research examined twins, the results are less likely to be impacted by genetic risk factors for dementia. Therefore, these findings offer unique insights into the TBI and dementia connection.