Almost Half of People with Concussion Still Show Symptoms of Brain Injury Six Months Later

Even mild concussion can cause long-lasting effects to the brain, according to researchers at the University of Cambridge. 

Using data from a Europe-wide study, the team has shown that for almost a half of all people who receive a knock to the head, there are changes in how regions of the brain communicate with each other, potentially causing long term symptoms such as fatigue and cognitive impairment.

Mild traumatic brain injury — concussion — results from a blow or jolt to the head. It can occur as a result of a fall, a sports injury or from a cycling accident or car crash, for example. 

But despite being labelled ‘mild’, it is commonly linked with persistent symptoms and incomplete recovery. Such symptoms include depression, cognitive impairment, headaches, and fatigue.

While some clinicians in recent studies predict that nine out of 10 individuals who experience concussion will have a full recovery after six months, evidence is emerging that only a half achieve a full recovery. This means that a significant proportion of patients may not receive adequate post-injury care.

Predicting which patients will have a fast recovery and who will take longer to recover is challenging, however. At present, patients with suspected concussion will typically receive a brain scan — either a CT scan or an MRI scan, both of which look for structural problems, such as inflammation or bruising — yet even if these scans show no obvious structural damage, a patient’s symptoms may still persist.

Dr Emmanuel Stamatakis from the Department of Clinical Neurosciences and Division of Anaesthesia at the University of Cambridge said: “Worldwide, we’re seeing an increase in the number of cases of mild traumatic brain injury, particularly from falls in our ageing population and rising numbers of road traffic collisions in low- and middle-income countries.

Dr Stamatakis and colleagues studied fMRI brain scans — that is, functional MRI scans, which look at how different areas of the brain coordinate with each other — taken from 108 patients with mild traumatic brain injury and compared them with scans from 76 healthy volunteers. Patients were also assessed for ongoing symptoms.

In results published today in Brain, the team found that just under half (45%) were still showing symptoms resulting from their brain injury, with the most common being fatigue, poor concentration and headaches.

The researchers found that these patients had abnormalities in a region of the brain known as the thalamus, which integrates all sensory information and relays this information around the brain. 

Counter-intuitively, concussion was associated with increased connectivity between the thalamus and the rest of the brain — in other words, the thalamus was trying to communicate more as a result of the injury — and the greater this connectivity, the poorer the prognosis for the patient.

Dr Stamatakis, who is also Stephen Erskine Fellow at Queens’ College, Cambridge, added: “We know that there already drugs that target these brain chemicals so our findings offer hope that in future, not only might we be able to predict a patient’s prognosis, but we may also be able to offer a treatment targeting their particular symptoms.”


Rebecca E Woodrow, Stefan Winzeck, Andrea I Luppi, Isaac R Kelleher-Unger, et al. Acute thalamic connectivity precedes chronic post-concussive symptoms in mild traumatic brain injury. Brain, 2023; DOI: 10.1093/brain/awad056 

University of Cambridge. (2023, April 25). Almost half of people with concussion still show symptoms of brain injury six months later. ScienceDaily. Retrieved May 10, 2023 from 

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