People who suffer from chronic traumatic encephalopathy (CTE) and have a family history of mental illness may be at increased risk for aggression in midlife, according to a study published in the Nov. 27, 2024, online edition of Neurology®the medical journal of the American Academy of Neurology.
CTE is a neurodegenerative disease associated with repeated head injuries, often seen in athletes and military personnel, which can lead to mood swings and dementia.
“This appears to be a case where these risk factors together add up to a greater risk of aggression than each alone, where people with CTE and a family history of mental illness are much more likely to engage in aggressive behavior than those with simply CTE or just family history,” said study author Jesse Mez, MD, MS, of Boston University Chobanian & Avedisian School of Medicine and a member of the American Academy of Neurology.
The study involved 845 men who were exposed to repetitive head impacts through contact sports or military service. A total of 329 of them played professional football. They all donated their brains for research after their deaths, which were at an average age of 60. Of the total group, 589, or 70%, had CTE and 383, or 45%, had a family history of mental illness.
The researchers interviewed participants’ family members or spouses about their aggressive behavior. They were also asked if participants’ parents, siblings, or children had ever been diagnosed with major depression, bipolar disorder, anxiety, post-traumatic stress disorder, obsessive-compulsive disorder, or other psychiatric or mood disorders. If any family member had a diagnosis, the participant was considered to have a family history of mental illness.
The researchers then divided the participants into four groups: 256 people, or 30%, with CTE and a family history of mental illness; 333 people, or 40%, with CTE and no family history of mental illness; 127 people, or 15%, without CTE and with a family history of mental illness; and 129 people, or 15%, without CTE and without a family history of mental illness.
The researchers asked family members about the participants’ aggressive behavior, such as whether they had harsh arguments with others or engaged in physical fights, where scores ranged from zero to 44. They found that during adulthood people with CTE and family history of mental illness had a mean score of 19 compared to people with CTE without a family history of mental illness who had a mean score of 17.
“This relationship was most striking for participants who died between the ages of 40 and 59,” Mez added.
After adjusting for other factors, such as total years playing contact sports and military history, the researchers found that those who died between ages 40 and 59 who had CTE and a family history of mental illness scored an average of 0.64 deviations highest standard on a scale. measuring aggression compared to those with CTE, but no family history of mental illness. For people who did not have CTE, having a family history of mental illness did not increase the risk of aggressive behavior.
“The link between a family history of mental illness and aggression may be due to a shared genetic background and also through a shared environment and common behaviors, such as childhood experiences with family members,” Mez said. “Identifying people who are most likely to show symptoms of aggression based on family history of mental illness would give us a way to predict the consequences of CTE and identify who may benefit most from treatment options.”
A limitation of the study was that it relied on past information from family members and spouses who may not have remembered the information accurately.
The study was funded by the National Institutes of Health, the Department of Veterans Affairs, and the Nick and Lynn Buoniconti Foundation.