Grey hair really is a sign of stress, say scientists.
When the going gets tough chemicals are triggered which damage DNA and leads us to look older and also increases the risk of diseases. Mice given an adrenalin-like compound to trigger stress had reduced amounts of a protein that keeps us healthy by protecting our cells from developing abnormalities.
Professor Robert Lefkowitz, of Duke University, North Carolina, said: "This could give us a plausible explanation of how chronic stress may lead to a variety of human conditions and disorders, which range from merely cosmetic, like greying hair, to life-threatening disorders like malignancies."
In experiments the researchers whose findings are published in Nature discovered a molecular mechanism through which adrenaline acted to destroy DNA.
Over four weeks the mice were inhected with the compound which led to degradation of the protein called p53 - dubbed the "guardian of the genome" for its role in preventing cancer - which was present in lower levels over time.
Prof Lefkowitz said: "We believe this paper is the first to propose a specific mechanism through which a hallmark of chronic stress, elevated adrenaline, could eventually cause DNA damage that is detectable."
The study also showed DNA damage was prevented in mice lacking a protein known as beta-arrestin 1.
Loss of it stabilised levels of p53 both in the thymus, an organ that strongly responds to acute or chronic stress, and in the testes where paternal stress might affect an offspring’s genome.
Co-researcher Dr Makoto Hara said: "The study showed chronic stress leads to prolonged lowering of p53 levels. We hypothesize this is the reason for the chromosomal irregularities we found in these chronically stressed mice."
The team is planning future studies in which mice are placed under stress by restraining them to creating their own adrenaline or stress reaction to show if their physical reactions also lead to DNA damage.
© The Telegraph Group London 2011