A new study suggests that a stimulating, learning environment early in life might actually help ward off neurodegenerative diseases later. The findings indicate that nurture may be more influential than nature when it comes to the brain's resilience against injury.
Researchers at Jefferson Medical College of Thomas Jefferson University in Philadelphia and at the University of Auckland in New Zealand found that rats living in a stimulating environment filled with running wheels, tunnels, balls and food had 45 percent less brain cell death commonly associated with normal development and aging than rats living in basic surroundings. What's more, the stimulated rats exposed to a neurotoxin were nearly completely protected from brain cell loss, unlike those in a normal environment. The scientists report their results in April in the journal Nature Medicine.
"We were hoping to get some scientific underpinnings to the age-old maxim, 'use it or lose it,'" explains neuroscientist Matthew During, M.D., director the Central Nervous System Gene Therapy Center at Jefferson and professor of neurosurgery at Jefferson Medical College. He and his colleagues wanted to see if an enriched learning environment would result in any protective effect on the brain.
Dr. During was surprised how robust the enriched rat brains were. "We showed in this study that an enriched environment switched on genes in the brain, and we believe by that mechanism the brain becomes super-resilient, resistant to aging and diseases, such as Alzheimer's, Parkinson's, and traumatic brain injury," he says.
"There haven't been many careful studies done in the lab to show if actively using your brain enhances your ability to stay healthy, and what mechanisms might be involved in protecting the brain," he says. "We asked what that [stimulating environment] would do to cognitive function, particularly in preventing brain cell death and symptoms of Alzheimer's and other diseases resulting in brain degeneration."
Rats housed in an enriched learning environment had running wheels, tunnels, rubber balls, a maze and a bar-pressing food station. They could choose their food and treats, such as corn chips. Rats living in standard conditions had no toys and only one food and water source.
Other scientists have shown in recent years that brain cell growth and replacement can occur throughout development and aging in animals and humans, while brain cell death occurs. According to Dr. During, his team's work provides the first compelling evidence that a stimulating environment along with early and continued learning not only protects the brain from disease but increases its capacity to repair and regrow damaged cells. "We've shown that a learning environment can encourage cell growth and also reduce cell death as well by about 45 percent. That includes both aging, old cells and young cells that spontaneously die."
The scientists also gave both sets of rats a neurotoxin, kainic acid. The brains of rats in the enriched surroundings were almost completely protected. "This is a rather dramatic finding," he notes.
Dr. During and his co-workers hope to better understand the mechanism, the specific environmental components and specific interventions most effective in protecting the brain. "We're asking if these genes we've shown to be active are actually switched on by the environment. What specific genes and chemicals are involved, and can we use these to actually improve the protection of the brain and treatment of diseases?"
Some of these chemicals are growth factors, such as GDNF, or glial cell derived neurotrophic factor, and BDNF, brain-derived neurotrophic factor, and transcription factors, such as CREB.
Journal
Nature Medicine