Bidirectional Relationship
Brain injury has been associated with acute cardiovascular dysfunction, including autonomic heart-brain axis dysregulation, imbalances between the sympathetic and parasympathetic nervous systems, and excessive catecholamine release, the authors noted.
Drs. Zafonte and Izzy suggested several plausible links between TBI and cardiovascular dysfunction, noting that they are “likely multifaceted, potentially encompassing risk factors that span the pre-injury, injury, and post-injury phases of the condition.”
TBI may induce alterations in neurobiological processes, which have been reported to be associated with an increased risk for CVD (eg, chronic dysfunction of the autonomic system, systemic inflammation, and modifications in the brain-gut connection).
Patients with TBI might develop additional risk factors following the injury, including conditions like posttraumatic stress disorder, depression, and other psychiatric illnesses, which are “known to augment the risk of CVD.”
TBI can lead to subsequent behavioral and lifestyle changes that place patients at an elevated risk for both cardiovascular and cognitive dysfunction when compared to the general population of TBI survivors.
There may be additional as yet undefined risks.
They believe there’s a bidirectional relationship between TBI and CVD. “On one hand, TBI has been associated with an elevated risk of CVD,” they said. “Conversely, cardiovascular risk factors such as diabetes, hypertension, hyperlipidemia, and sleep disturbances that have been demonstrated to negatively influence cognitive function and heighten the risk of dementia. Consequently, this interplay can further compound the long-term consequences of the injury.”
Their work aims to try and disentangle this “complex series of relationships.”
They recommend screening to identify diseases in their earliest and “most manageable phases” because TBI has been “unveiled as an underappreciated risk factor for CVD within contact sports, military, and community setting.”
An effective screening program “should rely on quantifiable and dependable biomarkers such as blood pressure, BMI, waist circumference, blood lipid levels, and glucose. Additionally, it should take into account other factors like smoking habits, physical activity, and dietary choices,” they recommended.
Heart-Brain Connection
Dr. Croll noted that TBI is “associated with many poorly understood physiologic changes and complications, so it’s exciting to see research aimed at clarifying this chronic disease process.”
In recent years, “we have seen a greater appreciation and understanding of the heart-brain connection,” she said. “Moving forward, more research, including TBI research, will target that connection.”
She added that there are probably “multiple mechanisms” at play underlying the connection between TBI and CVD.
Most importantly, “we are increasingly learning that TBI is not only a discrete event that requires immediate treatment but also a chronic disease process,” and when we “think about the substantial long-term morbidity associated with TBI, we should keep increased risk for CVD on top of mind,” said Dr. Croll.
The review received no funding. Izzy reported receiving grants from the US National Institutes of Health (NIH) and 2023 Stepping Strong Innovator Award. Dr. Zafonte reported receiving grants from the NIH and royalties from Springer and Demos publishing for serving as a coeditor of Brain Injury Medicine. Dr. Zafonte has also served as an adviser to Myomo, Oncare.ai, Nanodiagnostics, and Kisbee. He reported evaluating patients in the Massachusetts General Hospital Brain and Body–TRUST Program, which is funded by the NFL Players Association. The other authors’ disclosures are listed on the original paper. Dr. Croll declared no relevant financial relationships.
A version of this article appeared on Medscape.com.