Questions and Answers
Question # 6
Are there sex differences in the incidence of NLD?
Approximately 25 years ago, we found that the sex ratio of children who manifested NLD characteristics at assessment was approximately one girl for every 5 or 6 boys. Now, we find that the sex ratio is 1:1. It is clear that the gender role expectation revolution that has transpired during this period has contributed massively to this dramatic change in the gender ratio of clinical incidence; it is also apparent that the occurrence of this revolution has eventuated in a clinical incidence that is equivalent to the "true" incidence. Let me explain these two propositions.
First, it is apparent that young girls, at least in what we loosely refer to as "Western Society," are now expected to engage in roughly the same tasks (i.e., meet the same developmental demands) as do young boys. Girls are expected to engage in vigorous track and field events, contact sports, and other endeavours that used to be the almost exclusive domain of boys and young ladies referred to as "tomboys" a quarter of a century ago. In addition, girls are expected to do as well as boys in school subjects involving mathematics and science. The gender role revolution has changed dramatically the expectations that society (as reflected principally in the school) has for performances involving motor and psychomotor skills, visual-spatial-organizational skills, and concept-formation/scientific activities. Thus, it should come as no surprise that girls who present with difficulties in these areas (i.e., difficulties of the NLD sort) would be seen, even during the early school years, as in need of some form of assessment/intervention. Whereas, 25 or more years ago, the shy, withdrawn, psychomotorically incompetent girl who had difficulties with arithmetic/mathematics would be thought of as normally demure and essentially "feminine," such is not the case today. Hence, we have experienced a dramatic increase in the incidence of girls being referred for assessment because such characteristics are now viewed as "symptoms" or "problems," rather than "normal" feminine characteristics.
But, why should a ratio of 1:1 be viewed as the true incidence rate? There are two sets of answers for this. First, consider the following: There is no reason to believe that fetal teratogens, such as alcohol and other drugs, X-irradiation, and so on should affect the male fetus more or less than the female fetus; birth defects are not appreciably more common in boys than in girls (although there is some debate about this); given the more vigorous participation of girls in contact sports and in other activities such as motor vehicle driving, one would expect there to be, eventually, an equivalence in the incidence of significant traumatic brain injuries for both genders. All of these factors and many more that could be mentioned can lead to the manifestations of the NLD syndrome. Secondly, the origins of the NLD syndrome in some individuals (for example, those who exhibit Williams syndrome or Velocardiofacial syndrome) would appear to be related to genetic factors. For the most part, however, there is no compelling evidence at this point that would lead to the inference that such genetic factors are sex-linked (except, for example, in the case of Turner syndrome). It is clear that this issue is a complex one that needs to be investigated much more thoroughly.