Do you want to know how close you are to dying?

Researchers from the University of New South Wales have developed a fast and simple test to measure decline in brain function.

They found variability in people’s reaction time, rather than just the speed of their reactions, can better indicate accelerated ageing and a greater risk of death.

The team at the Centre for Healthy Brain Ageing studied 861 people, aged between 70 and 90, from the Sydney Memory and Ageing Study over eight years.

During the study about 20 per cent of the participants died.

Lead author Dr Nicole Kochan said the results held up even when conventional risk factors for death were taken into account.

“We now know that even discounting cognitive decline, these people with the more erratic response times could be closer to death,” she said.

If a person was more variable in their reaction time than the average of the study group, their risk of dying within eight years increased by 35 per cent.

Dr Nicole Kochan, from the UNSW Centre for Healthy Brain Ageing. Photo: ABC News/ David Coady

Dr Kochan suggested the inconsistent reaction times could become more exaggerated not only as you get older, but as you get closer to death.

“This test is valuable and interesting because we think it is a marker of the brain functioning,” she said.

“And in older people it could be a marker of accelerated ageing.”

She said some people found the test fun to start with, “unless they’re scared of computers”.

But some, she said, were worried about what the test might find out about their brain.

“As you get older you do notice a few memory lapses, it’s natural to have that,” she said.

“People start to worry and they think, ‘What’s the significance of that?’ ”

Researchers have developed a fast and simple test to measure decline in brain function. Photo: ABC News/David Coady

How does the test work?

Participants completed two computerised reaction-time tests to start, and then as part of comprehensive medical and neuropsychological assessments every two years.

Each person was presented with a large tablet screen, and told to hold their finger on the main black “home” circle.

Randomly, a coloured square appears on the screen, and the participant is meant to touch it as quickly as possible, before returning their finger to the home circle.

On a more-complex level, participants are required to make a choice between two squares they touch depending on a pre-specified rule.

The research, published in the PLOS ONE medical journal, reported greater, “intra-individual reaction time variability, but not average speed of response time, significantly predicted survival time”.

Earlier it’s caught, ‘better the chances for intervention’

Associate professor Michael Woodward is the chief medical adviser at Dementia Australia Victoria and the director of aged care research at Austin Health in Melbourne.

He described the current tests available as adequate in detecting the degree of cognitive impairment of a person.

“But detecting how much a person is going to decline in the future is not particularly adequate with the current test,” he said.

“It would be fair to say that most of the tests we’ve got are not particularly helpful in terms of determining a person’s risk of cognitive decline, a person’s risk of dementia or indeed a person’s risk of mortality.”

Dr Woodward said the earlier they could detect changes in a person’s brain, the more likely the chances for intervention.

“At the moment most of the interventions are experimental,” he said.

“But it’s very important that people are aware of them so that they can enrol in studies that might target the build-up of the toxic protein and the other changes that eventually lead to cognitive impairment and dementia.”

– ABC