Having concussion as a teenager could leave you suffering from multiple sclerosis (MS) when you get older, a new study shows.
Those who had a heavy knock to their head during those years are 22 per cent more likely to be plagued by the disease, scientists found.
But for those injury-prone adults who had concussion twice as a teenager, perhaps from falling off their bikes, the risk is more than doubled.
The results, led by Swedish researchers, demonstrate how important it is to protect risk-taking teenagers from severe head injuries.
Those who had a heavy knock to their head during their teenage years are 22 per cent more likely to be plagued by the disease, scientists found
However, the Örebro University and Karolinska Institutet team said the danger only exists to teenagers, and concussions in childhood pose no threat.
Lead researcher Professor Scott Montgomery suggested parents shouldn’t nanny their children to avoid any risky activities.
But he said more needs to be done to dampen the risk of head injuries, especially repeated ones, when playing sports.
Professor Montgomery, of Örebro’s School of Medical Sciences, added: ‘Teenagers often take risks, like cycling without a helmet.
‘If they knew about the possible long-term consequences, they might think again; perhaps they wouldn’t think it’s so cool to ride without a helmet.’
Some 100,000 people in the UK, and 400,000 in the US suffer with MS – and the disease affects twice as many women as men.
People who are affected suffer loss of mobility, sight problems, tiredness and excruciating pain – and there are few effective treatments.
The disease usually develops over time, where the body’s immune system attacks parts of the central nervous system.
Published in the Annals of Neurology, the new research based on medical records offers hope of finding a cure for the disease.
The researchers believe concussion triggers a similar response in the brain as that which causes the body’s immune system to attack nerve cells – as seen in MS.
Children are less likely to develop MS as a result of concussion because their brains are developing and can respond better to damage, scientists believe.
Professor Montgomery said: ‘The rapidly developing brain in earlier childhood may be more able to avoid some delayed consequences of trauma than in later teenage years.’
But not all adults who sustained severe head injuries as teenagers should worry, Professor Montgomery said.
He said that most ‘will not carry the necessary genetic factors and other risks that will result in MS in later life’.
Patients were split into two groups for the study. The first was those who sustained the head injury between birth and 10. The second was for those between 11 and 20.
MS risk in later adulthood was then examined by looking through their medical records to determine the link between concussions and the disease.