9 March 2005
Curiosity Cured The Rat
by Kate Melville
A study presented at the American Psychosomatic Society meeting suggests that female rats who are curious and more willing to step out and explore their environment tend to survive breast and pituitary tumors longer than their more cautious sisters.
Penn State researcher Dr. Sonia Cavigelli says that her study of 80 female rats from birth to death shows that the curious ones with tumors lived, on average, 25 percent longer lives, than the cautious ones. "Our new results with rats are consistent with those findings and support the notion that personality traits may have a significant impact on health and resilience to disease," she noted. "Tumor progression is a lengthy process and, therefore, may be particularly prone to subtle effects of personality on disease resilience."
The rats were tested as infants and as adults to see how curious or cautious they were by placing them in an environment populated with unfamiliar objects likely to intrigue rodents, including tunnels, bricks, stones and a small box. Some of the infant rats readily explored the environment and were designated "curious." Those that hesitated to emerge from the bowl used to introduce them into the environment were designated "cautious." The cautious and curious rats developed equal numbers of breast and pituitary tumors but those identified as more curious during infancy lived longer than the cautious ones. The difference in life span was comparable to several human years. "It's difficult to extrapolate from rats to people," she said. "However, there have been studies that show that shy elderly people report more health symptoms than their more outgoing age-mates."
Interestingly, the cautious females had lower stress hormone responses than the curious ones. This finding in female rats is the opposite of the results seen in an earlier study with male rats.The males' stress hormones were lower in the curious rodents. "These results suggest that both elevated and dampened stress hormone production may be associated with disease resilience or accelerated aging," she concluded.