Brain grows long after grey matter peaks

A key aspect of brain development continues until nearly age 50, researchers in the United States have discovered.

Their finding contradicts the current view that such maturation ends before 20, and may shed light on brain ailments such as Alzheimer's disease and schizophrenia.

The researchers, led by Dr George Bartzokis of the US Department of Veterans Affairs, used magnetic resonance imaging to measure brain development in 70 normal men aged from 19 to 76.

The researchers confirmed that so-called grey matter (the cerebral cortex) achieves peak development at the end of adolescence, then declines until old age.

But " white matter" (which sends signals from one part of the brain to another) continues developing in the frontal and temporal lobes on average until the age of 48, the study found.

"If your brain is the internet, grey matter is your computer and the white matter is the telephone lines that connect your computer to all the other computers on the planet," said Dr Bartzokis.

The associate chief of staff for mental health at the VA's Central Arkansas Veterans Health Care System said: "Most people think of the brain stopping development either in childhood or by the time we are adults." People were very different at 40 from at 17, he said. "You're really not the same person.

"And the issue is - are you not the same person because you just had an awful lot of experiences or are you not the same person because your computer (brain) is very different?

"This study suggests that your computer is very different."

Dr Bartzokis said that understanding how the structures of the brain developed and degenerated over the entire human life span was vital in gaining a better insight into Alzheimer's disease, schizophrenia and drug addiction.

The onset of Alzheimer's disease and schizophrenia is closely linked to age.

Alzheimer's disease is a degenerative brain disorder that manifests itself among primarily those over 65, although the disease may have been eating away at the brain for years.

The onset of schizophrenia, a brain disease characterised by delusions, typically is seen in young adulthood.

Dr Bartzokis said he focused on the frontal and temporal lobes - the front part of the brain where memory, higher reasoning and functions such as impulse control take place. These functions defined "who we are as humans," he said.

The brain abnormalities seen in Alzheimer's disease, schizophrenia and drug addiction such as cocaine dependence are seen in that part of the brain.

Dr Bartzokis used an imaging technique that maximised the ability to track white matter maturation in living people.



He suggested that imaging could be used to nail down what medications could promote brain development or prevent degeneration.

"It takes 20 to 30 years to manifest Alzheimer's even though it's eating up your brain, because you have reserve capacity.

"If you can measure that with imaging when you are 50 and you do an intervention when you are 50 and you change the trajectory (of the disease) even a little, all of a sudden instead of getting Alzheimer's at 70, you get it when you are 110.

"And then it's no longer a problem."

- REUTERS