Brain scan can reveal if you are lying about your age!

Scientists claim to have discovered a 'developmental clock' inside the human brain that can reveal exactly how old you really are.

Researchers say the discovery could have major implications for medicine, and gives new insight into how our brain changes with time.

It's a "carnival trick" that may have deeper implications for both brain science and medicine.

"We have uncovered a 'developmental clock' of sorts within the brain — a biological signature of maturation that captures age differences quite well, regardless of other kinds of differences that exist across individuals," said Timothy Brown of the University of California, San Diego School of Medicine.

Brown used magnetic resonance imaging (MRI) to scan the brains of 885 people ranging in age from 3 to 20.

Brain scans were used to identify 231 biomarkers of brain anatomy that, when combined, could assess an individual's age with more than 92 per cent accuracy.

According to researchers, that's beyond what's been possible with any other biological measure.

While scientists had looked at some of the same brain biomarkers in the past one by one, the key was finding a way to combine them to capture the multidimensional nature of brain anatomy and characteristic patterns of developmental change with age.

Brown says that they are excited to further explore the new approach and its potential for use in the clinic.

"The fact that we found a collection of brain measures that so accurately captures a person's chronological age means that brain development, or at least certain anatomical aspects of it, is more tightly controlled than we knew previously," Brown said.

"The regularity in this maturity metric among typically developing children suggests that it might be sensitive to detect abnormality as well," he said.

It's not yet clear how these anatomical changes in the brain will relate to maturity in terms of human behaviour, which we all know isn't necessarily reflected by our chronological age.

"The anatomy and physiology of these dynamic, interacting neural systems, which we can probe in different ways with MRI scans, have to account for the changes we all observe in human psychological development," Brown said.

"We're still figuring out exactly how," he said.

The findings are published in the journal Biology.