The human brain starts with a bang and ends with a moan.
It’s the conclusion of a project that used more than 120,000 brain scans to chart the organ’s changes throughout life. The results appear in the April 6 issue of the journal Nature.
Among the main results:
- The brain reaches 80% of its maximum size by age 3.
- Gray matter volume, which represents brain cells, peaks before age 6.
- White matter volume – a way to measure the connections between brain cells – peaks before age 29.
- White matter loss accelerates after age 50.
The current study could eventually lead to brain growth charts that would allow doctors to look for signs of atypical development in young patients. But for now, the results are intended for scientists studying typical brain growth or brain disorders like schizophrenia and Alzheimer’s disease.
One of the goals is “to use this enormous amount of existing data to help understand and treat psychiatric illnesses,” says one of the study’s authors, Dr. Aaron Alexander-Bloch, a psychiatrist at the University of Pennsylvania and Children’s Hospital of Philadelphia.
The project began over six years ago when two young researchers at a science conference started talking about a simple question: how does a person’s brain change over their lifetime?
They realized there was no right answer because most studies involving brain MRIs had been limited to a small number of people at any given time. In addition, the studies used different designs and kept their data in different forms.
So the researchers had an idea.
The researchers decided to turn more than 100 small studies into one big one.
“We could just put all these other studies and all these common datasets together to create some sort of ground truth and common language,” says Richard Bethlehem, a research associate in the University of Cambridge’s department of psychiatry.
Bethlehem and Jakob Seidlitz, a postdoctoral researcher at the University of Pennsylvania and Children’s Hospital of Philadelphia, began asking other researchers if they would contribute their study data to the effort.
“And really everyone came back and said, ‘That looks great, we should definitely do that,'” Seidlitz said.
The duo assembled an international team and began the hard work of turning over 100 small studies into one big one.
“Richard and I spent months organizing literally a lot of these datasets,” says Seidlitz.
They started to realize how different brains can be
Eventually, they had brain scan data from over 100,000 people, ranging from a fetus to a centenarian. And when they analyzed the data, they began to realize how different brains could be.
“One of the fundamental things that we started to see was just the wide variability in brain size throughout development,” says Seidlitz.
The team also found variations in the growth patterns of several dozen different areas of the brain’s outermost layer and in the volume of white matter, gray matter, subcortical gray matter and in the filled cavities. of fluid called ventricles.
Despite its enormous size, the study still had shortcomings, the researchers said, including a lack of racial and ethnic diversity. “That’s one of the things that humbled us,” he says.