By SUE VORENBERG
Scripps Howard News Service
September 27, 2006
The body stops producing gray matter - the stuff the brain's thinking lobes are made out of - at about age 16.
But white matter - the connective fiber between the lobes that allows parts of the brain to interact with each other - continues to grow until about age 45, according to the study by UNM's Health Sciences Center and New Mexico VA Health Care Systems.
"It looks like in some ways people between ages 35 to 45 are actually at their prime in terms of brain development," said Cheryl Aine, a UNM researcher and lead author of a paper that details the findings in the Oct. 1 issue of the journal NeuroImage.
Scientists used to think it was all downhill for the brain after the teenage years, because gray matter stops developing and shrinks as people enter their 20s, Aine said.
In the study, scientists looked at that theory more closely, by imaging the brains of people in three age groups - people 20-29, 35-45 and those over 60.
They found that gray matter becomes more refined, and the white matter "superhighway" that sends information between them actually keeps growing well into adulthood.
"We lose some of the gray matter because we get rid of the extra synapses we don't use," Aine said. "It's more sculpted after that, it's more efficient."
Earlier studies didn't look at white matter, because until about 10 years ago, the technology didn't exist to scan it, Aine said.
That's not to say that older brains are better at everything, said Janice Knoefel, a physician in geriatrics at the VA Hospital and a UNM professor of internal medicine and neurology.
When it comes to memory and learning, young brains still have an edge, said Knoefel, who also worked on the study.
"Attention tends to decline and memory tends to decline as we get older," Knoefel said. "But we use different strategies to remember things."
What of the folk explanation that older people have more things to remember, making it harder to cram information in?
"There is some truth to that," Knoefel said.
But the extra white matter also helps older people process and remember information more effectively by distributing it across more lobes of the brain, Aine said.
"As white matter matures, it gets faster," Aine said.
People in their teens and 20s are also better at visual and spatial reasoning, Knoefel said.
Language is another story.
"Language improves throughout the lifespan," she said. "We are exposed to language every day and our function with language is based on our experience with it. If you compare the vocabulary of a 20-year-old with an 80-year-old, the 80-year-old will be better at it."
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