South Australian researchers say a new drug has been identified that can help stop athletes from developing dementia after repeated head injuries.

Researchers have identified a new drug to help stop athletes from developing dementia after sustaining repeated head injuries.

The drug works to block a neurotransmitter called substance P which the brain releases in the event of a head knock.

Substance P causes an abnormal amount of a protein called hyperphosphorylated tau to collect inside neurons.

"Tau protein tangles are a feature of chronic traumatic encephalopathy (CTE), which reportedly leads to memory problems, confusion, personality changes, aggression, depression and suicidal thinking," University of South Australia Emeritus Professor Bob Vink said.

"Our research shows that by blocking substance P with a specific drug, we can prevent the tau protein tangles from developing in the brain and causing neurological problems."

Prof Vink said the findings of researchers in Adelaide, Melbourne and the US, would potentially have significant implications for athletes who play contact sports, such as boxers and footballers, as well as military veterans sustaining head injuries in conflict.

The link between concussion and neurogenerative diseases is well established.

A study of 14,000 Americans over 25 years, published in Alzheimer's and Dementia in March, showed that people who sustained even one head injury were 25 per cent more likely to develop dementia later in life.

This risk increased with multiple traumatic brain injuries.

The new drug has been successfully tested in animals, giving hope that CTE can be prevented in humans.

Prof Vink said the next step was human clinical trials, but that could take several years.