Can Head Injury Cause Dementia? Alzheimer's-Like Brain Plaques Seen In People With Past Traumatic Brain Injuries
Previous studies have showed the link between head injury and dementia. A new study reveals that the protein clumps that are usually seen in patients with Alzheimer's disease, the most common type of dementia, are also seen in those who suffered a head injury.
The study, conducted by researchers from Imperial College London, sheds light on the understanding of how people who have suffered serious head injury are at an increased risk of dementia later in life. For instance, veterans who suffered head injuries during combat were at an increased risk of developing dementia even after decades have passed.
"Research is increasingly showing that a blow to the head, such as that sustained in a road accident, triggers biological processes in the brain that burn away in the background for years," Dr. Gregory Scott, lead researcher of the study, says.
The researchers also found that the protein clumps, called amyloid plaques, are still present more than a decade after the injury.
In the study, featured in the journal Neurology, the authors used imaging procedures like magnetic resonance imaging (MRI) and positron emission tomography (PET) scanning to show images of the brains of patients who survived traumatic brain injury (TBI).
The nine patients involved in the study suffered moderate to severe TBIs, such as those caused by vehicular accidents, from 11 months to 17 years before the study was conducted. The brain scans showed images of the amyloid plaques in all participants, including the nine patients who had TBI, healthy volunteers and those already suffering from Alzheimer's disease.
The findings of the study show that those who suffered from TBIs had amyloid plaques in their posterior cingulate cortex and cerebellum. The posterior cingulate cortex is a highly connected and metabolically active brain region responsible for attention and memory, while the cerebellum is the part of the brain that regulates muscular activity.
The patients who had TBI were also found to have fewer amyloid plaques than those with Alzheimer’s disease, but more than the healthy volunteers.
When the researchers studied the link between the brain's white matter, also known as the brain wiring, and amyloid plaques in the posterior cingulate cortex, they found that the amyloid plaques were related to the amount of damage the white matter incurred during the injury. This means that the damage to the wiring of the brain may be associated with the formation of protein clumps.
"It suggests that plaques are triggered by a different mechanism after a traumatic brain injury. The damage to the brain's white matter at the time of the injury may act as a trigger for plaque production," said co-author, Dr. David Sharp of Imperial College London.
In 2010, 2.5 million emergency department visits, hospitalizations and even deaths were linked to TBIs. More than 50,000 people died of TBIs in the United States in 2010 and over the past decade, emergency department visits related to this injury increased by as much as 70 percent. It is considered as a major cause of death in the United States, contributing to about 30 percent of all injury deaths.
People who suffered from TBI may not feel any effects after recovery. This is because the consequences or complications of the injury itself are called hidden disabilities. It may take months or even years before symptoms appear. The person may seem to have fully recovered but they can have persistent problems, like the ones affecting their memory and concentration.
"If a link between brain injury and later Alzheimer's disease is confirmed in larger studies, neurologists may be able to find prevention and treatment strategies to stave off the disease earlier," Sharp added.
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