stress has been shown to have a negative effect on the immune system in many studies; for example, Kiecolt-Glaser et al (1984) found that exam stress reduced the function of important immune cells; other studies have shown that wounds are slower to heal when people are suffering from stress. Now new research by Rita Effros, professor of pathology and laboratory medicine at the David Geffen School of Medicine at UCLA, and a member of the Jonsson Cancer Center, Molecular Biology Institute and UCLA AIDS Institute may explain how stress ages the immune system.

Nature Nurture Debate: Born Lazy? Don't like going to the gym? Hate exercise? Now there's an excuse: new studies on mice have shown that the desire to exercise may be largely determined by genetic factors. This suggests that some people may find it easy to increase their activity levels to get healthy, while others will struggle.