Front Matter

Why Is There a “Spectrum” in Autism? 21

When describing a teratogen, one may think of three basic characteristics:

1. A given teratogen may be organ specific or cell receptor specific (i.e., like
   EDCs or synthetic chemicals) [63,64].


2. It may be species specific meaning only certain species may express recep­
   tors for those teratogens.


3. It can be dose specific meaning a very tiny dose may kill certain specific cells
   at a certain stage of gestation but may require much higher dose at a differ­
   ent stage of gestation (many synthetic chemicals fall into this group).
   Figure 1.11 illustrates the concept.
   The last point is where we think the “spectrum” manifests in ASD. The syn­
   thetic chemicals (i.e., fragrances, herbicides/pesticides and EDCs) hit specific
   brain progenitor cells in a developing fetus. For example, if a given chemicals
   enters a fetus brain and only binds to oxytocin receptors or olfactory neurons
   and kills those cells in the very early stages of gestation, it will result in total or
   almost complete deletion of those progenitor cells that are involved in social
   communication or olfaction (smell). In the early stage of gestation (i.e., 8 weeks
   of gestation), there may be only a few progenitor neurons that would ultimately
   represent the faculties of communication or olfaction. However, if the same
   chemical enters the fetal brain in the later stages of development (i.e., 24 weeks
   of gestation) at the same dose, then we would expect that there would be mil­
   lions of partially differentiated second or third progenitor neurons for oxytocin
   receptors or olfaction receptors, so they may only be partially damaged – layers
   of creating a “spectrum” of deficit (see Chapters 3 and 4). One can think of this
   in terms of how an oak tree grows. If one kills the seed, it will be akin to a
   miscarriage; if one cuts off a large branch when the tree is just 30 cm tall
   (equivalent to 15 weeks of fetal gestation), then the tree will be a lopsided oak
   (equivalent to showing some degree of neurologic deficit). However, if one cuts
   off multiple branches when the tree is 1 year old (32 weeks of gestation), the
   tree may grow almost normally and those branches will regrow (equivalent toa
   relatively small adverse effect being observed).
   Presented in a simplistic fashion, Figure 1.12 represents the changes just
   described.

Extreme disability Autism Asperger syndrome

Figure 1.11 A metaphoric illusion of ASD to colors of light.