Changes in the brain apparent in the blood in new TBI biomarker study

Jasmine Gill and Dr. Cheryl Wellington with the SIMOA HD-1 Analyzer at UBC.

Pictured: Dr. Cheryl Wellington (right) with graduate student Jasmine Gill (left) with the Simoa HD-1 Analyzer in the Wellington lab at the Djavad Mowafaghian Centre for Brain Health. Image credit: Paul Joseph/UBC.

A new study finds kids who have suffered a traumatic brain injury (TBI) have more of a particular protein in their blood than uninjured kids, suggesting a possible biomarker for TBI and a potential variable to distinguish levels of injury in children who have suffered mild TBI. The study, published this week in Lancet Child and Adolescent Health, is one of the largest of its kind and positions Canadian researchers at the forefront of pediatric TBI biomarker research and discovery.

The difficulty in finding a biomarker for brain injury is that the blood-brain barrier is a highly selective filter preventing substances from elsewhere in the body from affecting brain homeostasis. However, miniscule amounts of tau can find their way into the bloodstream. Tau is a protein that primarily accumulates in neurons in the brain and central nervous system and has been implicated in neurodegenerative diseases including Alzheimer’s disease and Chronic Traumatic Encephalopathy, which is believed to be a potential long-term consequence of many repeated concussions.

Until recently, it was difficult to quantify tau in blood because it occurs in trace amounts, but with the help of cutting edge donor-funded technology, Dr. Cheryl Wellington and her team have been able to detect tau in blood samples from children who have experienced a brain injury resulting in a visit to emergency rooms in Vancouver, Toronto, and Melbourne (Australia).  

“Our lab is now the go-to lab for blood biomarker testing using the Simoa technology in Canada,” said Dr. Cheryl Wellington, whose Simoa HD-1 Analyzer is the first tool of its kind in Canada. “To be able to detect changes in the brain via the blood is game-changing.”

Mild traumatic brain injury, which includes concussion, is the most commonly occurring head-related injury in children. While more severe brain injuries demonstrate more straightforward symptoms, there is evidence to suggest that the effects of mild traumatic brain injury can be equally long-lasting, but less is known about how mild TBI affects kids long-term.

In order to establish a prospective biomarker for mild TBI, Dr. Wellington and her team gathered samples from more than 300 healthy kids in order to establish a baseline for what “normal” blood tau levels should look like. They compared this with more than 130 samples from children ages 1 to 19 years who had reported to an emergency room with mild traumatic brain injury in order to determine whether tau was elevated in those cases.

They determined that blood tau was significantly increased following TBI.

“By leveraging a large volume of blood samples from the SickKids CALIPER biobank, we were able to establish valid normative data in order to inform our TBI study,” said Dr. Wellington. “This is the first study of its size to show a clear correlation between TBI and tau in children, and while more research is needed we are very encouraged by these results.”

By establishing a baseline for blood tau, Dr. Wellington hopes to move closer to pinpointing tau as evidence of changes in the brain post-injury. Children experience TBI in ways that differ from adults, and how the injury manifests and heals is highly variable based on age and developmental stage. By establishing a biomarker for mild TBI, clinicians will be better able to detect TBI with a simple blood test and determine a more individualized course of treatment.

“We are hopeful that we can make significant progress in our ability to diagnose and treat traumatic brain injuries,” said Dr. Wellington. “If we can detect even mild TBI in kids, we have the potential to improve outcomes for children and their families and reduce the risk of future concussions.”