Researchers working in the United States looked at the damage that occurs as a result of head injuries. The team used mice to focus on changes that take place in the brain’s waste clearance system upon head injury. They found that animals who received head injuries had faults in the normal clearance routes that take place in the brain. Such waste clearance mechanisms are essential to keep nerve cells healthy. They also showed that after head injuries, there was a build-up of the abnormal form of the protein tau – a hallmark of Alzheimer’s and other causes of neurodegeneration.
The researchers also looked at the effect of impairing the clearance system experimentally. They found that a faulty clearance system exacerbated the effects of traumatic brain injury; mice not only failed to clear abnormal tau, but performed worse on memory tests. The researchers suggest that this work could go some way to explaining why people who experience traumatic brain injury are at a greater risk of developing dementia.
Dr Simon Ridley, Head of Research at Alzheimer’s Research UK, said: “A key focus of research into Alzheimer’s and other neurodegenerative diseases is the build-up of abnormal, hallmark proteins such as amyloid and tau. However there is also a growing interest in a role for ‘faulty plumbing’ or reduced clearance of these proteins through different mechanisms.
“This new research, carried out in mice, highlights the damage that head trauma can cause to the finely balanced waste clearance system in the brain. It is important that researchers continue to investigate what might cause the observed link between head injuries and increased dementia risk in people, and where it sits in the context of the other risk factors for the condition.
“There are many risk factors associated with dementia, 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 in check could all help to maintain a healthy brain as we get older.”