It's not just our skin that sags with age: Our brains lose their youthful firmness and become 'slacker' as we get older

• The outer surface of the brain is covered in a number of folds called sulci
• UK researchers mapped these folds across the brains of 1,000 people
• They found they changed as people age, with the cortex losing elasticity
• Changes were more pronounced and started earlier in Alzheimer's brains

The numerous folds which cover our brains change over time, becoming slacker as we age, according to a study.

What’s more, this slacking was seen to be more pronounced in those with Alzheimer’s disease.

Researchers believe that learning more about how the mechanisms which control how folding changes with age could potentially be used to help diagnose brain diseases and spot dementia.

The outer surface of the brain is covered in a number of folds called sulci, which increase the surface area of cortex which can be packed into the skull.

To find the link between these wrinkles and the tension of the cerebral cortex, the team, led by researchers from Newcastle University, peered inside the skulls of more than 1,000 people to map their brains.

They found that as people age, the tension of their cortex appears to decrease.

'One of the key features of a mammalian brain is the grooves and folds all over the surface – a bit like a walnut – but until now no-one has been able to measure this folding in a consistent way,' explained Yujiang Wang, a mathematician modelling brain disease at Newcastle University and lead author of the study.

'By mapping the brain folding of over 1,000 people, we have shown that our brains fold according to a simple universal law.'

Dr Wang added: 'We also show that a parameter of the law, which is interpreted as the tension on the inside of the cortex, decreases with age. 

Just like the elasticity of skin begins to fade with age, they found that the brain lost its youthful appearance.

Neuroscientists have long known that the cortex – the outermost layer of brain tissue – is seen to shrink in those with Alzheimer's disease, but they found the loss of tension also increased in those with the condition. 

'In Alzheimer's disease, this effect is observed at an earlier age and is more pronounced,' explained Dr Wang. 

'The next step will be to see if there is a way to use the changes in folding as an early indicator of disease.' 

She added: 'More work is needed in this area but it does suggest that the effect Alzheimer's disease has on the folding of the brain is akin to premature ageing of the cortex.'

CHANGES TO BRAIN FOLDS

The outer surface of the brain is covered in a number of folds called sulci, which increase the surface area of cortex which can be packed into the skull.

Researchers mapped these folds in the brains of 1,000 people and found they changed with age, with the cortex losing elasticity and becoming more slack.

Changes were more pronounced and started earlier in Alzheimer's brains 

In addition to the link with disease, the study revealed clear differences between the brains of men and women.

Along with differences in size and surface area between the sexes, they found that female brains tend to be slightly less folded than male brains of the same age.

Despite this reduced folding, the brains follow exactly the same mathematical law, showing for the first time researchers have a consistent way of quantifying brain folding in humans