Ehp Niehs Nih Members 2001 Suppl 6 885 903muir Full

Ehp Niehs Nih Members 2001 Suppl 6 885 903muir Full

Neuro Development
December 2001 issue of EHP Supplements. Potentially even more disturbing is that a number ofepidemiologic studies suggest that the incidence of certaindisorders is on the rise. In the United States, the diagnosisof autistic spectrum disorders increased from 4-5 per 10,000children in the 1980s to 30-60 per 10,000 children in the1990s, according to a report in the August 2003 Journalof Autism and Developmental Disorders. Similarly, notesa report in the February 2002 issue of CNS Drugs,the diagnosis of ADHD grew 250% between 1990 and 1998.the number of children in special education programs classifiedwith learning disabilities increased 191% between 1977and 1994, according to an article in Advances in Learningand Behavioral Disabilities, Volume 12, published in1998.So what is going on? the short answer is that no onereally knows. There’s not even consensus on whatthe soaring rates actually mean. Heightened public awarenesscould account for the surge in the numbers, or it may bethat physicians are getting better at diagnosing the conditions.Some autism researchers believe the rise in that condition’sprevalence simply reflects changes in diagnostic criteriaover the last 25 years. On the other hand, some scientistsbelieve that the rates of NeuroDevelopment al disease aretruly increasing, and that the growing burden of chemicalsin the environment may play a role.with that in mind, investigators are considering theeffects of gene-environment interactions. A child witha mild genetic tendency toward a NeuroDevelopment al disordermight develop without clinically measurable abnormalitiesin the absence of environmental hits. However,children in industrialized nations develop and grow upin a veritable sea of xenobiotic chemicals, says IsaacPessah, director of the University of California, Davis,Center for Children’s Environmental Health and DiseasePrevention. Fortunately, he says, mostof us have a host of defense mechanisms that protect usfrom adverse outcomes. However, genetic polymorphisms,complex epistasis, and cytogenetic abnormalities couldweaken these defenses and amplify chemical damage, initiatinga freefall into a clinical syndrome.Pessah cites the example of autism. He says susceptibilityfor autism is likely conferred by several defective genes,no one of which can account for all the core symptoms ofsocial disinterest, repetitive and overly focused behaviors,and problems in communication. Could multiple genetic liabilitiesand exposure to a chemically complex environment act inconcert to increase the incidence and severity of the condition?Despite the uncertainties, many scientists believe itwould be wise to err on the side of caution when it comesto a research agenda. As Martha Herbert, a pediatric neurologistat Harvard Medical School, puts it, Even thoughwe may have neither consensus nor certainty about an autismepidemic, there are enough studies coming in with highernumbers that we should take it seriously. Environmentalhypotheses ought to be central to research now. the physiologicalsystems that have been harmed by environmental factorsmay also point to treatment targets, and this might bea great way to help the children.

Ehp Niehs Nih Members 2001 Suppl 6 885 903muir Full

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Ehp Niehs Nih Members 2001 Suppl 6 885 903muir Full Neurodevelopment
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