A third of children who suffer concussion go on to develop anxiety, depression or other mental health issues that can last for years, a study has claimed.
Scientists at Australia's Murdoch Children's Research Institute reviewed concussion studies including more than 89,000 children from the last 40 years.
Concussions are a common type of brain injury that can happen after a knock to the head. Most people recover but some have long-lasting complications.
More than 40 per cent of children in the study suffered a head injury after a fall and a further 30 per cent got it following a sports injury, such as heading a football.
Experts said it was not clear why the injuries led to mental health problems but that it could be linked to concerns over trouble concentrating and headaches.
One third of children who suffer concussion develop anxiety, depression and other mental health issues, a study has claimed. There has been a growing focus on the possible health impacts of children heading footballs regularly (stock image)
In the study scientists pored over papers published between 1980 and June last year to identify all those involving children suffering from a concussion.
They found 36.7 per cent experienced significantly higher levels of mental problems such as withdrawing, anxiety, depression and post-traumatic stress.
And 20 per cent became more aggressive, demanded more attention and were hyperactive compared with children who sustained other injuries.
The scientists also found pre-existing mental health problems made it more likely a child would suffer further issues after a concussion.
One in three people are walking around in a 'concussion-like daze' due to stress and lack of sleep, study suggests
From dizziness to memory loss, concussions are associated with a range of unpleasant symptoms.
Now, a new study has warned that around a third of people may be walking around with these symptoms, without suffering any head injury.
Instead, researchers say that stress and lack of sleep are causing these concussion-like symptoms.
The team hopes the findings will help doctors figure out which symptoms are due to head injuries and which have other causes.
A survey of more than 31,000 people showed that insufficient sleep, mental health problems, and stress were the causes of a whole host of symptoms doctors are used to seeing in head injury patients.
Symptoms included in what doctors call post-concussion syndrome (PCS) range from persistent headaches, dizziness and anxiety, to insomnia and loss of concentration and memory.
While 27 per cent of people reported several symptoms, between one half and three quarters said they experienced one - mainly fatigue or low energy and drowsiness.
But researchers believe the number in the general population could be much higher.
The American study, funded by the NCAA - the National Collegiate Athletic Association - and the US military, was designed to improve care for athletes and soldiers who suffered concussions.
Of those suffering from mental health problems because of an injury, 29 per cent had been diagnosed with the problem before their concussion.
The children's mental health tended to improve over time, with most recovering within six months after the injury, but a minority of children experienced symptoms that persisted for years afterwards.
MCRI researcher Alice Gornall, who led the study, said: 'Despite the high incidence of concussion among children and adolescents, identifying those at risk of ongoing difficulties after concussion remains a prominent challenge for clinicians.
'On top of this, children take twice as long to recover from concussion than adults, with one in four children experiencing symptoms beyond one month after injury.'
Experts have previously raised concerns over how sports activities, such as heading a ball, could stunt children's mental development.
Scientific trials over the past decade have established a clear link between repeated concussions and chronic traumatic encephalopathy (CTE) — a degenerative brain disease which can lead to dementia.
Mounting evidence over the potential dangers of head contact has led to increased awareness in physical sports such as football, American football, boxing and rugby.
Repeated blows to the head suffered on the field, from colliding with other players in the case of rugby, are thought to be the cause of the irreversible damage.
Children under the age of 12 are already banned from heading footballs in training in England, Scotland and Northern Ireland, and under-18s can only head the ball a restricted number of times in training.
Researchers last year called for sponge balls to be used during children's training sessions and for referees at grassroots levels to measure the ball pressure before match kick offs.
Parents and children have raised concerns over the impact of injuries to the head on youngsters' daily lives.
Emma Henry, 17, was given as an example in the study after she was left suffering from mental health issues following two concussions a year apart.
She first knocked her head on a goal post while playing netball in 2019, and was hit in the back of the head by a ball the following year.
Miss Henry said she developed anxiety, headaches, a sense of hopelessness and had trouble concentrating after the second concussion.
'After my last concussion I found it very hard to be motivated for school and everyday life,' she said.
'Doing the simplest of tasks such as a walk was difficult for me, not being able to complete these tasks got me quite disheartened which impacted on my mental health.'
Her father, Bruce, said: 'When a child has a concussion they might look fine but you can't see the underlying impact.
'It's so important for mental health to form part of concussion management, which has been essential to Emma's recovery process.'
BRAIN INJURIES IN SPORTS: FAST FACTS ABOUT CTE RISKS, TESTS, SYMPTOMS AND RESEARCH
As athletes of all sports speak out about their brain injury fears, we run through the need-to-know facts about risks, symptoms, tests and research.
1. Concussion is a red herring: Big hits are not the problem, ALL head hits cause damage
All sports insist they are doing more to prevent concussions in athletes to protect their brain health.
However, Boston University (the leading center on this topic) published a groundbreaking study in January to demolish the obsession with concussions.
Concussions, they found, are the red herring: it is not a 'big hit' that triggers the beginning of a neurodegenerative brain disease. Nor does a 'big hit' makes it more likely.
In fact, it is the experience of repeated subconcussive hits over time that increases the likelihood of brain disease.
In a nutshell: any tackle or header in a game - or even in practice - increases the risk of a player developing a brain disease.
2. What is the feared disease CTE?
Head hits can cause various brain injuries, including ALS (the disease Stephen Hawking had), Parkinson's, and dementia.
But CTE is one that seems to be particularly associated with blows to the head (while the others occur commonly in non-athletes).
CTE (chronic traumatic encephalopathy) is a degenerative brain disease that is caused by repeated hits to the head.
It is very similar to Alzheimer's in the way that it starts with inflammation and a build-up of tau proteins in the brain.
These clumps of tau protein built up in the frontal lobe, which controls emotional expression and judgment (similar to dementia).
This interrupts normal functioning and blood flow in the brain, disrupting and killing nerve cells.
Gradually, these proteins multiply and spread, slowly killing other cells in the brain. Over time, this process starts to trigger symptoms in the sufferer, including confusion, depression and dementia.
By the later stages (there are four stages of pathology), the tau deposits expand from the frontal lobe (at the top) to the temporal lobe (on the sides). This affects the amygdala and the hippocampus, which controls emotion and memory.
3. What are the symptoms?
Sufferers and their families have described them turning into 'ghosts'.
CTE affects emotion, memory, spatial awareness, and anger control.
4. Can sufferers be diagnosed during life?
No. While a person may suffer from clear CTE symptoms, the only way to diagnose their CTE is in a post-mortem examination.
More than 3,000 former athletes and military veterans have pledged to donate their brains to the Concussion Legacy Foundation for CTE research.
Meanwhile, there are various studies on current and former players to identify biomarkers that could detect CTE.