Think About Tomorrow Between Those Head Impacts

The Late Contributions of Repetitive Head Impacts and TBI to Depression Symptoms and Cognition.

Alosco ML, Tripodis Y, Baucom ZH, Mez J, Stein TD, Martin B, Haller O, Conneely S, McClean M, Nosheny R, Mackin S, McKee AC, Weiner MW, Stern RA. Neurology. 2020 Jun 26. Epub Ahead of Print.
https://pubmed.ncbi.nlm.nih.gov/32591472/

Take-Home Message

Middle to older aged adults that report a history of repetitive head impacts or traumatic brain injury reported slightly worse depressive symptoms and cognitive scores than people without exposure to head impacts or brain injury.

Summary

Repetitive head impacts may lead to problems later in life (depression, cognitive dysfunction, neurodegenerative disease). However, it remains uncertain if repetitive head impacts contribute to these problems because prior studies had limitations (lack of a control group, focus on American football, small sample sizes). Therefore, the authors used the Brain Health Registry to determine if measures of depression or cognition differed among middle-age and older adults with or without a history of repetitive head impacts or traumatic brain injury. Participants over 40 years of age completed demographic and health questionnaires, self-reported measures of repetitive head impact exposures and traumatic brain injury history, depressive symptomology, and computer neuropsychological tests. The authors then grouped the 13,323 participants into 6 groups based on their reported history of repetitive head impacts and traumatic brain injury with or without loss of consciousness. People who reported a history of repetitive head impacts or traumatic brain injury (regardless of the loss of consciousness) had more depressive symptoms scores and poorer working memory scores than people with no history of head impact nor brain injury. Finally, people with self-reported brain injury and loss of consciousness performed worse on several cognitive outcome measures compared to the group who reported no history of head impact nor injury.

Viewpoints

The authors used a large registry of middle age to older adults and found evidence that people reporting repetitive head impacts or traumatic brain injury may also report more depressive symptoms and experience cognitive dysfunction. This study is also interesting as it overcame some prior limitations. Specifically, the authors analyzed a large sample from a more generalizable population rather than a potentially biased brain sample registry. Another advantage of the registry was that it had data on people with no exposure to repetitive head impacts and traumatic brain injury. However, due to the retrospective nature of the study, we are unable to state that these exposures caused depressive symptoms and cognitive dysfunction. Future studies may help clarify causation and how much of the relationship between trauma that may lead to PTSD (e.g., abuse) – which represented ~43% of the cases – and depressive symptoms or cognitive dysfunction is influenced by repetitive head impacts or brain injury. If repetitive head impacts or brain injury is a big part of that relationship, then therapies that target the pathologic changes (e.g., damage to glial cells) may be needed as part of the therapeutic plan. However, if repetitive head impacts or brain injury play a small part in that relationship, then it may be beneficial to focus more on other aspects of the therapeutic strategy (e.g., mental health consultations). It is also critical to note that the authors reported that the clinical meaningfulness of these outcomes is unclear because the differences between groups were small. Furthermore, less than 20% of participants had clinically meaningful symptoms of depression. Hence, without knowing if the groups differ in how many people met the threshold for clinically meaningful symptoms of depression, it is challenging to infer that these relationships are clinically relevant. Large longitudinal studies will be necessary to clarify the meaningfulness of these findings; however, they do support the commonly held hypothesis that exposure to head impacts or brain injury may increase the risk of poor long-term outcomes. At this time, clinicians should be aware that repetitive head impacts and brain injury may relate to depressive symptoms and cognitive abilities later in life. Hence they should support rule changes and preventative programs that decrease the number of head impacts one may suffer.