A study of twins shows that having a concussion early in life is tied to having lower scores on tests of thinking and memory skills decades later as well as having more rapid decline in those scores than twins who did not have a concussion, or traumatic brain injury (TBI). The study is published in the September 6, 2023, online issue of Neurology, the medical journal of the American Academy of Neurology.
The study involved 8,662 men who were World War II veterans. The participants took a test of thinking skills at the start of the study when they were an average age of 67 and then again up to three more times over 12 years. Scores for the test can range from zero to 50. The average score for all participants at the beginning of the study was 32.5 points.
A total of 25% of the participants had experienced a concussion in their life.
Twins who had experienced a concussion were more likely to have lower test scores at age 70, especially if they had a concussion where they lost consciousness or were older than 24 when they had their concussion. Those twins with traumatic brain injury with loss of consciousness, more than one traumatic brain injury and who had their injuries after age 24 were more likely to have faster cognitive decline than those with no history of traumatic brain injury.
For example, a twin who experienced a traumatic brain injury after age 24 scored 0.59 points lower at age 70 than his twin with no traumatic brain injury, and his thinking skills declined faster, by 0.05 points per year.
These results took into account other factors that could affect thinking skills, such as high blood pressure, alcohol use, smoking status and education.