Tuesday, June 29, 1999 Published at 17:41 GMT 18:41 UK
Pigs offer anorexia clues
Leaner pigs showed anorexia-like symptoms
Lean pigs are helping psychiatrists unravel the origins of anorexia, a conference has heard.
Pigs that are bred to be slim to satisfy consumer demand for lean bacon are more sensitive to stress, researchers reported.
The Royal College of Psychiatrists' annual meeting in Birmingham heard that four per cent of them also exhibited classic signs of anorexia nervosa such as overactivity and not eating.
Such pigs have genetic traits that predispose them to slimness, and researchers are interested in whether or not anorexia is inherited.
Earlier studies have been divided on the issue.
However, others point to examples of families where anorexia occurs over two or more generations, or among sisters.
Dr Janet Treasure, senior lecturer at London's Institute of Psychiatry, told the conference: "There does seem to be a genetic disposition to leanness in the families of anorexics."
The researchers are particularly interested in the role played by genes involved in the body's control of serotonin, a chemical that helps govern mood.
Dr Treasure has compared 48 pairs of sisters, one of whom in each pair had anorexia.
"In the sisters with anorexia it had nothing to do with overweight or dieting. That's not a risk factor," she said.
"What we found was a high level of perfectionism, low self esteem and a strong need to comply. The sisters with anorexia were more likely to say things like 'my parents always want me to achieve'.
"Those without anorexia would not feel the need to comply or would say 'oh sod it'."
She said it seemed as though the sisters with anorexia were more likely to have variations in the genes related to serotonin.
Dr Treasure said: "It's important to realise there is a mixed vulnerability to anorexia. It's not due to either genes or environment, it's an interaction between the two.
"Anorexia nervosa is a complicated disorder and genes aren't everything. The genes load the gun but the environment pulls the trigger."