A large study in the United States suggests that traumatic head injury in mid-life onwards can increase dementia risk.
The study, published on 27 October in the journal JAMA Neurology, followed 164,661 people over the age of 55, without a prior diagnosis of dementia, who were hospitalised with some form of trauma. Of these, 51,799 had sustained a head injury. The researchers followed these people for between five and seven years, comparing those with head trauma to people who had trauma in other areas of the body e.g. fractures. Those who had sustained a head injury were slightly more likely to go on to develop dementia than those who had experienced non-head traumas, This link was still observed when the researchers accounted for age and other factors that may affect dementia risk such as high blood pressure and diabetes.
The researchers also rated the severity of the head injury. They found that those with moderate or severe head injuries were at greater risk of dementia over the age of 55. Mild head injuries appeared to increase dementia risk only in people over 65. The authors tried to account for ‘reverse causality’; the possibility that dementia may cause an increased likelihood of injury, by excluding anyone who developed dementia within a year of their injury.
Dr Simon Ridley, Head of Research at Alzheimer’s Research UK, the UK’s leading dementia research charity, said:
“The association between head injuries and dementia risk is one that has gained increasing attention in recent years. This large study suggests that head injuries in later life, mainly from falls, may increase a person’s risk of developing dementia, particularly over the age of 65.
“It will be important for researchers to further investigate the link between brain injury and dementia, to fully understand the biology behind the relationship and where it sits in the context of the other lifestyle factors that may alter the risk of the condition. The risk factors associated with dementia are varied and complex, with age, genetics and lifestyle all likely to play a part. Current evidence suggests that a balanced diet, regular exercise, not smoking and keeping blood pressure and cholesterol in check could all help to maintain a healthy brain as we get older.”