Keith Sracosic / AP
The human brain begins with a bang and ends with a threat.
This is the conclusion of a project that charts organ changes over a lifetime using more than 120,000 brain scans. The results will appear in the April 6 issue of the journal Nature.
In the original search:
- At 3 years of age, the brain reaches 80% of its maximum size.
- The amount of gray matter, which represents brain cells, is highest before the age of 6 years.
- The amount of white matter – a way of measuring the connection between brain cells – is highest before the age of 29 years.
- The loss of white matter accelerates after the age of 50 years.
Ongoing studies could eventually lead to a brain growth chart that allows doctors to look for signs of atypical development in young patients. But for now, the results are for scientists who typically study brain disorders such as brain enlargement or schizophrenia and Alzheimer’s disease.
One goal is to “use this vast amount of existing data to help understand and treat mental illness,” said study author Dr. Aaron Alexander-Bloch, a psychiatrist at the University of Pennsylvania and at Children’s Hospital of Philadelphia.
The project began more than six years ago when two young researchers at a scientific conference began talking about a common question: How does a person’s brain change over a lifetime?
They realized that there was no better answer because most studies involving MRI brain scans were limited to a small number of people at one time. Also, different designs have been used in the study and their data has been kept in different formats.
So the researchers had an idea.
Researchers have decided to turn more than 100 small studies into one large study
Richard Bethlehem, a research associate in the Department of Psychiatry at the University of Cambridge, says, “We can combine all these other studies and all these general data sets to create some kind of ground truth and a common language.”
Bethlehem and Jacob Seidlitz, a postdoctoral researcher at the University of Pennsylvania and Children’s Hospital of Philadelphia, have begun to ask other researchers if their research data would contribute to this effort.
“And really everyone came back and said, ‘It looks great, we must do it,'” Sidlitz said.
The pair have brought together an international team and started working hard to turn more than 100 small studies into one big one.
“Richard and I literally spent months curating many of these data sets,” Sidlitz said.
They begin to understand how different brains can be
Finally, they had brain scan data on more than 100,000 individuals, from embryos to centenarians. And when they analyze data, they begin to understand how different brains can be.
“The basic thing we’re starting to see is the sheer variability of how big the brain gets during development,” says Sidlitz.
The team also found differences in dozens of different regions of the outer layer of the brain and in the type of growth of white matter, gray matter, subcortical gray matter, and fluid-filled cavities known as ventricles.
Despite its enormous size, there are still gaps in research, researchers say, including a lack of ethnic and racial diversity. “It’s something we’ve been humbled by,” he said.