WORLD-FIRST STUDY CHARTS HOW OUR BRAINS DECLINE AS WE AGE
The charts could one day be used as a clinical tool to help track patients’ brain development and diagnose neurodevelopmental disorders
The first comprehensive study of how the human brain changes over a lifetime could help doctors to monitor and diagnose neurological conditions such as Alzheimer’s. The study, led by researchers at the University of Cambridge and the University of Philadelphia, has produced a unique set of charts based on brain scans that range from those of a 15-week-old foetus all the way up to a 100-year-old adult.
So far, the researchers have identified a number of developmental milestones, including a rapid growth burst that begins at around 17 weeks after conception, when the brain is around 10 per cent of its full size. This growth spurt then ends at around three years of age, when the brain has reached around 80 per cent of its full size.
They also found that the volume of grey matter, the part of the brain made up of neurons, peaks at around six years old before beginning to slowly decrease. White matter – the tissue that sends messages between different areas of grey matter – was found to peak at around 29 years old and then decline after we reach 50 years old.
The project began when Dr Richard Bethlehem, of the University of Cambridge, and Dr Jakob Seidlitz, of the University of Pennsylvania, met at a conference. It pulls together data from nearly 125,000 MRI brain scans taken from more than 100 studies worldwide.
“This very much started as a grassroots initiative, essentially between just me and Jakob, at a conference a couple of years ago. We just said to each other, ‘wouldn’t it be cool if we could pool all these different research studies together to create a reference point or an anchor point for any future work?’” Bethlehem said.
“We basically started to reach out to people in our network and also started cold-calling people that had published on specific datasets or specific periods of the lifespan to ask if they wanted to come on board.”
“Although the charts are not ready for use in the clinic, the aim is to map out typical changes that occur in the brain as we age”
The team pieced together the charts by using imaging software to extract data such as the volume of grey and white matter or the thickness of the cortex – the brain’s outer covering – from their huge bank of MRI scans. They estimate that the charts, which can be viewed on the open access site www.brainchart.io, took around two million hours of computing time to produce.
Although the charts are not ready for use in the clinic, the aim of the project is to map out typical changes that occur in the brain as we age. This data could then be used in much the same way that height and weight charts are used to monitor the development of children. Eventually, they could provide information on how the brain differs in neurological conditions such as Alzheimer’s disease, which causes loss of brain tissue.
“If you think about the situation as it exists currently, someone will have a brain scan because there’s already suspicion that something might be off. And an expert like a radiologist or a neurologist will look at that scan and using all their expertise and knowledge and experience, say, ‘yeah, we can clearly see there’s something not quite right in this scan’. But that’s not a quantitative statement,” said Bethlehem.
“They can’t say it looks atypical by this much relative to where you should be if you’re this age or gender. Hopefully what this tool can provide in the future is something that’s a little bit more quantitative. Something where you can say all this is extreme, but it’s extreme by this much or it’s changed by this much over time.”
The researchers hope to expand the dataset to include more scans taken from under-represented socioeconomic and ethnic groups as well as analysing the current data in finer detail.
“We just scratched the surface with this dataset in terms of defining the milestones in the paper,” said Seidlitz. “In the future, we really hope to hone in on more concrete developmental epochs that have been done in other domains, like in molecular biology, genetics and transcriptomics.”