The Neurochemical Basis of Autism

Withtherecentlyperceivedincreaseinincidenceofautismandtherealizationthat “autism”mayactuallybe“autisms”withsubsetsofaffectedindividuals,researchers have been pursuing the possibility that there may be multiple etiologies for the disorder.Althoughmostautismstudieshavefocusedongeneticsandadvancedn- roimaging,thereisapaucityofresearchaimedatdeterminingtheneurochemical basisofautism.Identifyingcoreneuralsubstratesorkeybiomarkersisessentialto understandingthemechanisticbasisthatmayinpartunderlie“autisms.”Alterations inmolecules,proteins,receptors,andsynapticelementsaresomeofthecontrib- ingsubstratesthatcouldresultinaltereddevelopmentalprocesses,changedsynaptic function,andaberrationsinconnectivity.Itisnowapparentthatmultiplebrainareas are affected in autism, and neuropathological defects have been described within corticalandsubcorticalnetworks.Althoughrecentprogresshasbeenmadeinid- tifyingsomeofthegenesthatmayunderliethedisorder,muchattentionhasalso beengiventoepigeneticand/orenvironmentalfactorsthatmaycontributetosubsets ofautisticindividuals. The contributors to this book were hand selected because of their expertise in their respective ?elds. Individually each chapter presents a unique perspective into the clinical, developmental, neurochemical, and/or physical chemical basis of autism. The contributing authors summarize current research ?ndings in their respective areas and also present novel ideas and propose hypotheses and p- sible mechanisms that may be operative during development and the potential consequencesofhavingdefectsinspeci?cmolecules,receptors,orgenes. Thesubtitle“FromMoleculestoMinicolumns”wasinsertedbecauseofmuch recent attention given to alterations in the basic organization of mini- or mic- columns of neurons in cerebral cortical areas in autism. These especially include prefrontalcorticalareasthatundergoanovergrowthduringearlypostnataldevel- mentinmanyindividualswithautism.Tothisend,theworldrenownedDr.Alan Peters,theneuroanatomistthatoriginallydescribedmini-ormicro-columnaror- nizationinthecerebralcortex,wasrecruitedtowriteachapterinthisbookgiving hisexpertperspectiveontheissueinautism. The book begins with highly respected clinician, Dr. Margaret L. Bauman, DirectoroftheLADDERSclinicintheBostonarea,withaclinicalandmedicalp- spectiveofautismdiscussingetiologies,clinicalpresentation,earlyidenti?cation, vii viii Preface advancementsinmedicalcare,andassociateddisorders.Inthechapter“TheMale Prevalence in Autism Spectrum Disorders: Hypotheses on its Neurobiological Basis”,ItalianresearchersDrs.FlavioKellerandLilianaRutapresentneuroch- ical hypotheses as the basis for the predominance of male prevalence in autism discussing the possible roles of estrogen, testosterone, oxytocin, and vasopressin in the organization of brain circuits and hemispheric specialization. Psychiatrist Dr. Ricardo Vella relates neuropathologies in autism, in the limbic and cereb- lar regions, to speci?c behaviors and presents a developmental perspective and hypotheses regarding emotional and attachment behaviors in autistic individuals.