Functional Connections From the Thalamus Can Predict Concussive Symptoms After a Mild Traumatic Brain Injury
Post by Kulpreet Cheema
The takeaway
Functional changes in the connectivity of a brain region called the thalamus in the acute phase after a mild traumatic brain injury (mTBI) can be used to indicate chronic symptoms.
What’s the science?
After a person suffers from a mTBI, it’s often hard to predict long-term symptoms, with studies showing that clinicians often overestimate recovery rates. The thalamus is a brain region that is involved in the coordination of information between different brain regions. Disrupted thalamic activity is found to be associated with various post-concussive symptoms like headache, sleep disturbance, and fatigue. Additionally, a significant relationship has been found between thalamic activity and symptoms of depression, pain, and cognitive performance. However, these studies had small sample sizes and often investigated patients with pre-existing disorders. It is therefore unclear whether this relationship is due to mTBI alone. This week in Brain, Woodrow and colleagues aimed to study the pathophysiology of the thalamus and its relationship with the post-concussive symptoms that emerge after a mTBI.
How did they do it?
The authors used magnetic resonance imaging (MRI) data from the CENTER-TBI study, which included 108 patients with mTBI with no history of previous concussion or neuropsychiatric disorder and 76 healthy control participants. All participants completed a structural MRI scan and a resting state functional MRI (rsfMRI) scan in the acute phase of their injury. Thirty-one patients also completed the same scans at 6- and 12 months post-injury. Behavioral assessments were conducted to measure cognitive, emotional, and somatic symptom recovery.
The thalamus' overall volume and functional connectivity (i.e., degree of correlated activity between the thalamus and other brain regions) and six blood-based injury biomarkers collected within 30 days were related to the outcome. In addition, functional connectivity was related to the density of receptors and transporters from nine neurotransmitter systems.
What did they find?
In the acute phase after mTBI, the thalamus had an increased number of functional connections to other brain regions when compared to controls. Surprisingly, changes in routine imaging and blood-based biomarkers were not different between the patients and controls. Moreover, patients who developed persistent postconcussive symptoms had even more connections from the thalamus than those without symptoms, proposing this as a biomarker of chronic symptoms. Also, specific neurotransmitter profiles were related to the functional connectivity changes associated with post-concussive symptoms. Together, all these results suggest the chronic symptoms after a mTBI can be identified and better understood by examining the functional connectivity of the thalamus, in conjunction with different neurotransmitter profiles.
What’s the impact?
The study found that functional connectivity of the thalamus can serve as an earlier biomarker after a mTBI injury. This can help clinicians identify patients who will develop post-concussive symptoms and improve appropriate treatment plans to alleviate these symptoms.
