The overwhelming majority of referrals for a diagnostic assessment for Asperger's Syndrome are boys. The ratio of males to females is around 10:1, yet the epidemiological research for Autistic Spectrum Disorders suggests that the ratio should be 4:1. Why are girls less likely to be identified as having the characteristics indicative of Asperger's Syndrome? The following are some tentative suggestions that have yet to be validated by academic research, but they provide some plausible explanations based on preliminary clinical experience. It appears that many girls with Asperger's Syndrome have the same profile of abilities as boys but a subtler or less severe expression of the characteristics. Parents may be reluctant to seek a diagnostic assessment if the child appears to be coping reasonably well and clinicians may be hesitant to commit themselves to a diagnosis unless the signs are conspicuously different to the normal range of behaviour and abilities.

We have a stereotype of typical female and male behaviour. Girls are more able to verbalise their emotions and less likely to use physically aggressive acts in response to negative emotions such as confusion, frustration and anger. We do not know whether this is a cultural or constitutional characteristic but we recognise that children who are aggressive are more likely to be referred for a diagnostic assessment to determine whether the behaviour is due to a specific developmental disorder and for advice on behaviour management. Hence boys with Asperger's Syndrome are more often referred to a psychologists or psychiatrist because their aggression has become a concern for their parents or schoolteacher. A consequence of this referral bias is that not only are more boys referred, clinicians and academics can have a false impression of the incidence of aggression in this population.

Each person with Asperger's Syndrome develops their own techniques and strategies to learn how to acquire specific skills and develop coping mechanisms. One technique is to have practical guidance and moral support from one's peers. We know that children with Asperger's Syndrome elicit from others, either strong maternal or `predatory' behaviour. If the person's natural peer group is girls, they are more likely to be supported and included by a greater majority of their peers. Thus girls with Asperger's Syndrome are often `mothered' by other girls. They may prompt the child when they are unsure what to do or say in social situations and comfort them when they are distressed. In contrast, boys are notorious for their intolerance of children who are different and are more prone to be `predatory'. This can have an unfortunate effect on the behaviour of a boy with Asperger's Syndrome and many complain of being teased, ignored and bullied by other boys.

It is interesting to note that some boys with Asperger's Syndrome actually prefer to play with girls who are often kinder and more tolerant than their male peers. The author has conducted both individual and group social skills training with boys and girls with Asperger's Syndrome. Experience has indicated that, in general, the girls are more motivated to learn and quicker to understand key concepts in comparison to boys with Asperger's Syndrome of equivalent intellectual ability. Thus, they may have a better long-term prognosis in terms of becoming more fluent in their social skills. This may explain why women with Asperger's Syndrome are often less conspicuous than men with the syndrome and less likely to be referred for a diagnostic assessment. The author has also noted that, in general, mothers with Asperger's Syndrome appear to have more `maternal' and empathic abilities with their own children than men with Asperger's Syndrome, who can have great difficulty understanding and relating to their children.

When a child would like more friends but clearly has little success in this area, one option is to create imaginary friends. This often occurs with young girls who visualise friends in their solitary play or use dolls as a substitute for real people. Girls with Asperger's Syndrome can create imaginary friends and elaborate doll play which superficially resembles the play of other girls but there can be several qualitative differences. They often lack reciprocity in their natural social play and can be too controlling when playing with their peers. This is illustrated in Liane Holliday-Willey's autobiography.

The fun came from setting up and arranging things. Maybe this desire to organise things rather than play with things, is the reason I never had a great interest in my peers. They always wanted to use the things I had so carefully arranged. They would want to rearrange and redo. They did not let me control the environment

When involved with solitary play with dolls, the girl with Asperger's Syndrome has total control and can script and direct the play without interference and having to accept outcomes suggested by others. The script and actions can be an almost perfect reproduction of a real event or scene from a book or film. While the special interest in collecting and playing with dolls can be assumed to be an age appropriate activity and not indicative of psychopathology, the dominance and intensity of the interest is unusual. Playing with and talking to imaginary friends and dolls can also continue into the teenage years when the person would have been expected to mature beyond such play. This quality can be misinterpreted as evidence of hallucinations and delusions and a diagnostic assessment for schizophrenia rather than Asperger's Syndrome.

The most popular special interests of boys with Asperger's Syndrome are types of transport, specialist areas of science and electronics, particularly computers. It has now become a more common reaction of clinicians to consider whether a boy with an encyclopaedic knowledge in these areas has Asperger's Syndrome. Girls with Asperger's Syndrome can be interested in the same topics but clinical experience suggests their special interest can be animals and classic literature. These interests are not typically associated with boys with Asperger's Syndrome. The interest in animals can be focussed on horses or native animals and this characteristic dismissed as simply typical of young girls. However, the intensity and qualitative aspects of the interest are unusual. Teenage girls with Asperger's Syndrome can also develop a fascination with classic literature such as the plays of Shakespeare and poetry. Both have an intrinsic rhythm that they find entrancing and some develop their writing skills and fascination with words to become a successful author, poet or academic in English literature. Some adults with Asperger's Syndrome are now examining the works of famous authors for indications of the unusual perception and reasoning associated with Asperger's Syndrome. One example is the short story, "Cold" in `Elementals: Stories of Fire and Ice' by A.S. Byatt.

Finally, the author has noted that some ladies with Asperger's Syndrome can be unusual in their tone of voice. Their tone resembles a much younger person, having an almost child like quality. Many are concerned about the physiological changes during puberty and prefer to maintain the characteristics of childhood. As with boys with Asperger's Syndrome, they may see no value in being fashionable, preferring practical clothing and not using cosmetics or deodorants. This latter characteristic can be quite conspicuous.

These tentative explanations for the apparent under representation of girls with Asperger's Syndrome have yet to be examined by objective research studies. It is clear that we need more epidemiological studies to establish the true incidence in girls and for research on the clinical signs, cognitive abilities and adaptive behaviour to include an examination of any quantitative and qualitative differences between male and female subjects. In the meantime, girls with Asperger's Syndrome are likely to continue to be overlooked and not to receive the degree of understanding and resources they need.

Reference:

Holliday-Willey, L. (1999) Pretending to be Normal: Living with Asperger’s Syndrome. London. Jessica Kingsley Publications