April 21 (UPI) -- Researchers at the University of Gothenburg in Sweden found athletes who had multiple concussions may have other injuries in their brains causing symptoms.
The study, from the Sahlgrenska Academy at the University of Gothenburg, calls into question the relationship between concussions and Alzheimer's disease
"There seem to be two separate conditions and pathologies involved here," Dr. Pashtun Shahim, researcher of neurology and physiology at Sahlgrenska Academy, said in a press release.
Researchers analyzed 28 athletes, primarily elite male and female ice hockey players from Sweden, who had long-term health problems including depression, irritability, memory problems, concentration problems and sensitivity to light and sound after having multiple concussions.
The study found they all had a general change in the metabolism of a protein called amyloid precursor protein, or APP. Alzheimer-related beta-amyloids are excreted from APP in the synapses or nerve-cell connections in the brain.
This effect may indicate synaptic damage in the brain after multiple concussions, along with an element of inflammation.
"At the same time, however, the results do not indicate that there is any plaque pathology like you would see in, for example, Alzheimer's, which is a very important discovery," Shahim said.
Researchers found that the changes mainly affected the hockey players who had been experiencing concussion-related complaints for a long-time period of more than a year. Other players did not produce the same results, nor did the 19 healthy individuals in the control group.
"These findings indicated that there is a connection between the long-term complaints suffered following a concussion and nerve cell damage -- the first time that these two could be linked, with evidence found in living contact sport athletes," Shahim said. "This means that we can follow up on these people in five or ten years' time and see how their problems have developed."
The study was published in Neurology.