The relationship between autism spectrum, Fragile X syndrome, and Submissiveness personality trait as mediated by BDNF is complex. Here we see a study suggesting that BDNF-mediated cortical anatomy is contrary to normal in individuals with autism spectrum; that is, usually higher BDNF such as with BDNFval allele would usually produce greater cortical surface area, but lower BDNF (BDNFmet) produces this in individuals with autism spectrum. This is in the context of many studies which have suggested high BDNF (and thus BDNFval allele) in individuals with autism spectrum. But, the authors pondered that since cortical surface area is higher in autism spectrum, BDNF signaling in the brain and not just concentration in the brain may be awry in individuals with autism spectrum.
Here in a mouse model, lower activity BDNF (met) was one of the genes involved with premature ovarian failure, a phenotype associated with Fragile X syndrome premutation carriers.
And, also in a mouse model, here BDNF decreases FMRP expression, this thought to be a mechanism whereby BDNF exerts neuro-plasticity effects.
Taken together these studies give support to the ideas regarding the propencity of individuals with Submissiveness trait to have autism spectrum diagnoses and/or to have Fragile X syndrome; that is, if an individual has Submissiveness trait, he would likely have, given an association with BDNFmet allele, lower BDNF production and thus higher plasticity effects if the same individual doesn't have Fragile X syndrome and even higher plasticity if the individual has Fragile X syndrome. Since plasticity appears to be related to learning and memory, the results are clear. If neurons have high plasticity, there may be more pathways formed in neurodevelopment, thus producing the larger brain seen in the individual with autism spectrum. While more pathways sound like an improvement, this is a clear pathway for atypical thinking and neuro-atypia, in general, seen with Autism spectrum. The possible implication for the understanding of schizophrenia and other abnormal thinking patterns is also clear. Just as Submissiveness trait stands at the center of abnormal and normal behavior in personality theory, the candidate genes for Submissiveness trait, here BDNFmet, also stand at the center of behavioral atypias.
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