People who suffer multiple traumatic brain injuries are more likely to have worse cognitive function later on in life, new research suggests.

Incidents like falls, road accidents and assaults that lead to head injuries can have long-term health effects at an older age, such as struggling to concentrate or increased risk of dementia, according to a UK-based study.

Researchers at UNSW Sydney analysed nearly 16,000 people in the UK and found concussions were linked to worse brain function in later years.

Participants who reported just three episodes of even a mild concussion had a reduced ability to concentrate and complete complex tasks.

Meanwhile, those with four or more mild concussion episodes showed a decline in processing speed and working memory.

Participants were aged 50 to 90 years old and suffered their last head injury an average of 29 years prior to the study and their first head injury an average of 39 years earlier.

"What our study showed is that even if you've had concussions in your 20s, 30s, 40s - if you've had three or more, we can see the significant difference between you or your group and people who have never been concussed in your 60s, 70s and 80s," lead author and UNSW PhD Candidate Dr Matthew Lennon MD told AAP.

"And that's something really interesting and new and it shows that it's not just athletes but the general population who can experience these cognitive side effects from having a concussion."

The study is the largest ever to explore the cognitive effects of concussion or traumatic brain injury.

Helen Brooker, a study co-author from the University of Exeter, said cognitive rehabilitation is a viable solution in some cases.

"Our findings indicate that cognitive rehabilitation should focus on key functions such as concentration span and completion of complex tasks, which we found to be especially susceptible to long-term damage."

A spokesperson from the Department of Health and Aged Care said government support is available.

"Although the exact relationship between concussion in younger years and cognitive function in later years is not entirely understood, it is important to promptly identify and appropriately treat concussion when it occurs," a department spokesperson said.

"Most patients with traumatic brain injury will have ongoing care needs met by primary care providers such as general practitioners and allied health professionals. People with a Medicare card can get free or lower cost medical services by doctors, specialists and other health professionals, prescription medicines and mental health care."