A series of papers published in European Eating Disorders Review finds:

a peak season of birth in March/April among people with anorexia although there are similarities, there are also differences, between anorexia in males and females.

The lead researcher, Prof. Arthur Crisp, argues in defence of the concept that anorexia nervosa is rooted in a biologically based avoidance behaviour, driven by a phobia of normal adult body weight.

The seven papers, previously unpublished, derive from data collected between 1960-1995 by Prof. Crisp and a team of researchers based first at the Middlesex Hospital Medical School and subsequently at St. George's Hospital Medical School in London.

Information about the first 980 patients on the St. George's database was compared with that on season of births in the general population. The population of anorectics born before 1964 showed a trough in their season of birth in February, and peaks in March/April and October. There was a similar peak for those born in 1964 and after.

One factor - the presence of maternal preoccupation and body weight and shape, and maintaining it at normal levels - was found to be significantly associated with this peak in births. A background of severe/moderate anorexia in the mother was also important.

751 females and 62 males with anorexia were studied. Compared with the general population, there was a much greater likelihood of anorexia in the mothers of both males and females with anorexia. Onset of illness was later in males, and earlier in non-White females, reflecting differences in growth rate and the close link between the disorder and puberty.

There were tendencies for laxative abuse to be more common among females, and for vegetarianism to be more common in males. A significant difference was found for males in veganism and alcohol abuse. Females were significantly more likely to hoard food.

The majority of female teenagers want to weigh less than they do. By the age of 16, two-thirds of girls report feeling overweight, and have tried to diet. This can lead to wildly fluctuating daily calorie intake, which may spill over into 'dietary chaos' - including the extreme bingeing-vomiting pattern of bulimia nervosa.

In anorexia nervosa, however, there is sustained and severe calorie restriction. Prof. Crisp suggests that this single-minded rejection of food brings relief, in the absence of other psychological defences, from what has become overwhelming panic.

This panic results from problems experienced during the development of puberty, which have previously seemed insoluble. Only such panic-driven flight, he says, can overcome the powerful forces of natural growth that takes place in puberty.

He argues that anorexia nervosa is rooted in a biologically based avoidance behaviour driven by a phobia of normal body weight. The phobia, and its intensity, may be denied, but will be revealed if normal body weight is restored.

Without help, the avoidance behaviour may remain the only alternative to suicide. However, with treatment of the kind developed at St. George's Hospital there is evidence that long term mortality from the condition is significantly reduced whilst full recovery is more common, including restored fecundity. Thus the population of about 70 recovered patients produced between them 115 healthy children.

interscience.wiley/journal/erv