A brain is a terrible thing to waste. To this, Marian Cleeves Diamond readily concurs, saying, "Use it or lose it."
In three decades of brain research, Diamond has helped revolutionize the way we think about aging.
"We now know that with proper stimulation and an enriched environment, the human brain can continue to develop at any age," she said, speaking from her office in the university's department of integrative biology.
Her work used middle-aged rats - the equivalent of 60-year-old humans - and some with brains corresponding to humans at age 90. In each case, Diamond and her colleagues were able to show that with added enrichment - in this case, colorful toys and balls, exercise equipment and other stimulating rodents for the company - the size and cognitive agility of the rats' brains improved.
Rats reared together with a changing variety of toys and other stimuli were much better at running mazes than rodents reared in more isolation or deprived of stimulation. Their brains also looked different, Diamond said. They had many more branching or sprouting dendrites, nerve cells, blood vessels and a thicker cerebral cortex (the area central to thinking skills).
"We used middle-aged rats partly because they have a similar cortex to humans," Diamond said.
At 69, Diamond says it was "comforting to find we can change the brain at any age. We're saying that if you use your brain, you can change it as much as a younger brain." She said it may take the older brain longer to respond, but change does happen.
She said people would be wise to think of their brain as any other muscle. Left in isolation, evidence shows, brain cells begin to shrink and shut down.
These findings are particularly interesting in light of recent studies indicating that higher education and/or full development of the brain's cognitive abilities early in life may help protect people from the ravages of Alzheimer's in old age.
A landmark study of older nuns who had donated their brains to science found that those who showed an early ability to write prose rich in ideas and dense in meaning were far less likely to die from Alzheimer's than those whose early writing was more impoverished in ideas.
Scientists analyzing the so-called Nuns Study theorize that a more fully developed brain may be better able to switch on a sort of reserve power pack as one ages, giving it greater ability to ward off neurological invaders, or a stronger system for slowing diseases like Alzheimer's.
As early as the 1940s, Yale University child development specialists A.L. Gesell documented the withering effect that deprivation, lack of stimulation and simple human contact had on infants and young children.
Left unattended in their cribs, with no one speaking to them or hugging them, infants gradually took on a wizened, monkeylike appearance. Normal development - speech, cooing, talking and crawling - was retarded, and they aged physically.
Today, Diamond and others in the field are convinced the brain's development can be altered through early stimulation and re-energized throughout life.
"The common sense brain research began with Gesell, but now we have been able to quantify brain changes in the lab," said Diamond. "Others are doing the same in humans."
At the Berkeley campus, Diamond is something of a legend and a role model for older colleagues. Her students lionize her and often interrupt her lectures with applause.
In 1981, she was named one of the three most popular college professors in the nation. In 1989, the Council for Advancement and Support of Education selected her as its California Professor of the Year. This year the UC alumni association named her alumna of the year, one of only four women to win the honor in the 53 years it's been given.
Outside the classroom, she is a devoted parent, an avid tennis player and a hiker who has scaled Kilimanjaro and Mount Whitney as well as many peaks in the Rockies and Himalayas. She also paints and sculpts with her husband, Arnold Scheibel, UCLA professor of neuroscience and psychiatry.
Diamond says it's time to redefine the notion of retirement, starting with the word itself. "We're trying to change the name of `retire' to `redirect'. The one has a negative connotation. It means slow down; the other is a challenge to do something different," she said.
"This is important especially if we are genetically programmed to live until about 100 and people are still thinking of retiring in the old sense at 60 or 65."
She has followed her own advice. At 64, she became director of Berkeley's Lawrence Hall of Science, a hands-on museum and teaching facility with a stunning view of the San Francisco Bay. One of her exhibits there was, naturally, on the brain.
Her physician father first piqued her fascination with this vital organ when she was a teenager and he took her on rounds at Los Angeles County Hospital.
Much later, Diamond found out that Albert Einstein's brain was in a jar of formaldehyde in Missouri. For years, she tried to get a few slivers of the physicist's brain to test a theory of how geniuses' brains differ from other people's. Finally, the tissue samples arrived in a mayonnaise jar. She tested them and discovered that her theory was right.
Now back teaching and doing research, Diamond is looking at the cerebral cortex and its role in immune function. This quest is quite personal. She hopes her findings will shed light on lupus, an immune system disorder that killed her sister and brother.
Researchers already have shown that they can reinvigorate the immune system with a transplant from the thymus gland. Diamond says she will focus on this fertile area.
"I owe it to my family."