A routine blood test could soon help doctors diagnose concussion in older Australians more accurately and quickly, according to new research from Monash University and The Alfred that may change the way head injuries are identified in one of the country’s most vulnerable populations.
For decades, diagnosing concussion has relied heavily on a patient’s ability to describe what happened and explain their symptoms. But for older adults, that process is often far from straightforward.
Memory problems, fatigue, confusion and difficulty concentrating are all recognised signs of concussion. They are also common features of ageing, making it difficult for clinicians to distinguish between a mild traumatic brain injury and normal age-related changes.
Now, researchers have identified a blood-based biomarker that could provide the objective evidence doctors have long been searching for.
Concussion, also known as mild traumatic brain injury (mTBI), is a major and growing health issue worldwide. Older adults experience the highest rates of traumatic brain injury-related hospitalisations and deaths, with falls representing the leading cause of head injuries in this age group.
Unlike younger patients, older people often face a more complicated recovery after concussion. They are more likely to experience prolonged symptoms, slower rehabilitation and poorer health outcomes.
At the same time, diagnosis can be difficult.
A person may not remember the incident clearly. Some may have lost consciousness. Others may present with symptoms that overlap with conditions such as dementia, stroke, delirium or the side effects of multiple medications.
“The diagnostic process is often ambiguous,” said lead researcher Dr Gershon Spitz from Monash University’s School of Psychological Sciences.
“Doctors frequently rely on information reported by patients themselves, which can be affected by memory loss, confusion and other factors associated with head injury.”
The new study, published in JAMA Network Open, investigated whether proteins released into the bloodstream after a brain injury could help identify concussion in adults aged 60 years and older.
Researchers recruited 89 participants between the ages of 60 and 84. The group included healthy volunteers, patients with clinically diagnosed concussion and a smaller group whose injuries were suspected but difficult to confirm using traditional diagnostic methods.
The standout performer was a protein known as glial fibrillary acidic protein, or GFAP.
GFAP is released by specialised support cells in the brain called astrocytes when they are damaged. Researchers found that people who had experienced concussion had significantly higher levels of GFAP in their blood compared with healthy participants.
Importantly, GFAP demonstrated excellent diagnostic accuracy, correctly distinguishing concussion cases from healthy controls with an adjusted accuracy score of 0.93 on a scale where 1.0 represents perfect discrimination.
The biomarker performed consistently whether blood samples were taken within 24 hours of injury or later within a 72-hour window.
Perhaps most strikingly, GFAP remained highly effective even in patients whose brain scans showed no obvious signs of injury.
One of the study’s most significant findings involved patients who fell into what clinicians describe as the diagnostic “grey zone”.
These individuals had experienced a plausible head injury and reported symptoms consistent with concussion, but lacked the objective clinical signs normally required for a formal diagnosis.
When researchers applied personalised GFAP thresholds adjusted for age and sex, two-thirds of these patients showed biomarker levels consistent with brain injury.
A second biomarker, brain-derived tau (BD-tau), was elevated in almost 90 per cent of these uncertain cases.
The findings suggest blood biomarkers may help clinicians identify concussions that would otherwise go undetected.
Under current clinical practice, many patients with mild head injuries undergo observation and CT scans to rule out serious complications such as bleeding on the brain. However, a normal scan does not necessarily mean the brain has escaped injury.
Professor Biswadev Mitra, an emergency physician at The Alfred and chief investigator on the study, believes the test could fill an important diagnostic gap.
“Patients may still have significant concussive injuries that are not detected through conventional assessment,” he said.
“For older patients at risk of falls, the ability to identify concussion while they are still in the emergency department could help reduce the risk of future falls and improve long-term outcomes.”
A key discovery from the study was that biomarker thresholds cannot be applied universally.
Researchers found that normal GFAP levels increase naturally with age, meaning an 84-year-old requires a much higher diagnostic threshold than a 60-year-old.
The optimal GFAP cutoff nearly doubled across that age range, rising from around 100 picograms per millilitre to more than 200 picograms per millilitre.
Without age-specific thresholds, doctors risk generating false positives in older patients or missing genuine injuries in younger ones.
The study also identified sex-related differences in some biomarkers, highlighting the need for personalised interpretation rather than a one-size-fits-all approach.
While the test is still in the research phase, the implications extend well beyond hospital emergency departments.
Senior author Professor Sandy Shultz from Monash University’s School of Translational Medicine said blood-based concussion testing could eventually become a valuable tool for paramedics, aged care providers and regional health services.
“Timing is critical for effective concussion treatment, particularly in older adults who often have other health conditions that complicate diagnosis,” Professor Shultz said.
“A quick and efficient diagnosis is key to supporting healthy ageing and better long-term outcomes.”
The technology builds on earlier biomarker research conducted in younger populations but is the first to demonstrate strong diagnostic performance specifically in older adults.
The researchers caution that larger studies will be needed before the test becomes part of routine clinical practice. The study was conducted at a single Melbourne trauma centre and involved a relatively small number of participants.
Even so, the results offer compelling evidence that blood biomarkers could become an important addition to concussion assessment.
For a condition that has long depended on subjective symptoms and uncertain recollections, an objective blood test may provide clinicians with something they have lacked for decades: clear biological evidence that a concussion has occurred.
As Australia’s population ages and fall-related injuries continue to rise, that breakthrough could have a profound impact on patient care, helping doctors identify hidden brain injuries earlier and giving older Australians a better chance of recovery.
