Thus, the altered expression of genes involved in steroid hormone production and sexual dimorphism, coupled with the differential impact of male and female steroid hormones on brain development in male vs. female animals [78], [79] may, in part, underlie the approximately 4∶1 male to female ratio in ASD.
ApoE is involved in neural regeneration of the peripheral nervous system through the redistribution of cholesterol [ 48] therefore it is possible that it is in this role that ApoE affects brain development in the precocious male.
And then later, with further male pregnancies, the high levels of antibodies directed toward this substance may change brain development in these later born males," says lead researcher Tony Bogaert in a media release.
Moreover, trade-offs can occur at many different levels and our analysis do not provide a complete picture of all potential aspects that could be negatively affected by the maintenance of resources into brain development in the early maturing sneaker males.
We investigated if early sexual maturation was associated with brain development in Atlantic salmon (Salmo salar), in which males can either stay in the river and sexually mature at a small size (sneaker males) or migrate to the sea and delay sexual maturation until they have grown much larger (anadromous males).
The latest study, from the universities of Cambridge and Utrecht, tests the idea that the disorder may be the result of an "extreme male brain", perhaps compromised by exposure to male sex hormones during brain development in the womb.
Understanding the biology of male and female brain development in health and illness may provide important clues as to the mechanisms of disease and eventually guide more effective interventions.
If sexual maturation and the mating behaviours associated with reproduction have a positive influence on neural development, we predict that early maturing males will have increased relative brain development in relation to other treatments.
Two independent empirical articles have recently appeared in the literature that, taken together, bear out an hypothesis Blanchard (2008) postulated in the Archives about brain development in transsexualism: [T]he brains of both homosexual and heterosexual male-to-female transsexuals probably differ from the brains of typical heterosexual men, but in different ways.
The results are consistent with the idea that testosterone pushes brain development in a more autistic direction and that autism is the manifestation of an "extreme male brain".
