Charting brain development to track changes as we age : Shots - Health News A study of more than 120,000 brain scans shows rapid growth before age 2 and accelerating decline after age 50. The results may one day help pick up abnormalities in the developing brain.

Scans reveal the brain's early growth, late decline and surprising variability

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STEVE INSKEEP, HOST:

The human brain starts with a bang and ends with a whimper. That's the conclusion of a project that used more than 120,000 brain scans to chart the brain's rapid growth, gradual decline and remarkable variability. NPR's Jon Hamilton has more.

JON HAMILTON, BYLINE: The project began with two young researchers who had a simple question. How does the brain change over a person's lifespan? They realized there was no good answer because most studies that use MRI brain scans are limited to a few people at a single point in time. So the researchers had an idea.

RICHARD BETHLEHEM: Wouldn't it be cool if we could just stitch together all these other studies and all these different data sets to really create some kind of ground truth and a common language?

HAMILTON: That's Richard Bethlehem from the University of Cambridge in the U.K. He and Jakob Seidlitz from the University of Pennsylvania began approaching researchers who did brain scans with a request.

BETHLEHEM: This is what we're trying to do. Do you want to help out? And really, everyone came back and said, this looks great. Like, we should definitely be doing this.

HAMILTON: The pair assembled an international team and began the hard work of turning more than 100 small studies into one big one. Bethlehem says, eventually, they had brain scan data from more than 100,000 people.

BETHLEHEM: The youngest individual was about 15, 16 weeks post conception. And then, I think, last time I checked, the oldest individual we have is slightly over 100 years old.

HAMILTON: The results of the study appear in the journal Nature and include a series of growth charts. One shows that by age 3, the brain has reached 80% of its maximum size. But Seidlitz says that size fluctuates from person to person a lot.

JAKOB SEIDLITZ: One of the fundamental things that we started to see was just the sheer variability of how big the brain gets throughout development.

HAMILTON: Seidlitz says the team also found a lot of variation in the growth patterns of structures and types of tissue within the brain.

SEIDLITZ: The different tissue compartments or the constituent parts of the brain that make up the whole themselves have really quite amazing dynamics that are different.

HAMILTON: For example, the volume of gray matter, which represents brain cells, peaks at about age 6. Meanwhile, white matter, which represents the connections between cells, peaks at age 29. The study found that both white and gray matter begin a slow decline following their peak. And after age 50, the decline in white matter begins to accelerate. Dr. Aaron Alexander-Bloch, a psychiatrist at the University of Pennsylvania, says the study results are intended primarily for researchers, not parents.

AARON ALEXANDER-BLOCH: Right now, it's not the time to take your kid to the doctor's office and ask where their brain is on a growth chart.

HAMILTON: For one thing, the current collection of brain scans lacks racial and ethnic diversity. But Alexander-Bloch says eventually, brain growth charts could help doctors spot early signs of disorders, including Alzheimer's disease and schizophrenia.

Jon Hamilton, NPR News.

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