Concussions Can Lead to Earlier Onset of Alzheimer’s, Study Reports

Concussions can accelerate brain deterioration and cognitive decline in people genetically predisposed to Alzheimer’s, leading to earlier onset of the disease, according to a study.

The findings could shed light on concussions’ impact on neurodegeneration and on Alzheimer’s incidence and development, researchers said.

The study, “Mild traumatic brain injury is associated with reduced cortical thickness in those at risk for Alzheimer’s disease,” was published in the journal Brain.

Research has shown that those who experience a moderate to severe brain injury are 4 1/2 times more likely to develop Alzheimer’s late in life than other elderly people. But scientists didn’t know the role that a mild brain injury or concussion played in the neurodegenerative process or in the risk of a person developing Alzheimer’s.

A Boston University School of Medicine team used magnetic resonance imaging (MRI) to measure the thickness of the cerebral cortex, or outer layer of the brain, in 160 war veterans between the ages of 19 and 58.

Participants were divided into two groups. One consisted of veterans who had suffered one or more concussions, the other those who had never had a concussion.

The measurements covered 14 brain regions. Seven of the 14 are the first to show the tissue atrophy associated with Alzheimer’s. As a control, the researchers measured seven regions that do not usually show Alzheimer’s-related tissue deterioration.

“We found that having a concussion was associated with lower cortical thickness in brain regions that are the first to be affected in Alzheimer’s disease,” Jasmeet Hayes, the author of the study, said in a press release. “Our results suggest that when combined with genetic factors, concussions may be associated with accelerated cortical thickness and memory decline in Alzheimer’s disease relevant areas.”

A key discovery was that brain anomalies showed in a number of relatively young people — those with an average age of 32. This suggested it is possible to detect the impact of a concussion early in life.

The results underscored the influence a concussion can have on neurodegeneration. They also highlighted the importance of doctors documenting concussions and watching for symptoms. “When combined with factors such as genetics, the concussion may produce negative long-term health consequences,” Hayes said.

It is still unclear what concussion-related mechanisms are involved in accelerating the development of neurodegenerative diseases, so more studies are required, she said. “Treatments may then one day be developed to target those mechanisms and delay the onset of neurodegenerative pathology,” she added.