A new possible cause for Autism?

Here's a new possible cause of autism I got through email:

Autism May Be Caused by Thyroid Deficiency Early in Pregnancy

Prof. Gustavo C. Román MD

The cause of autism remains unknown but the increase in prevalence suggests environmental factors in its causation. There are well defined changes in the brain of patients with autism. These include prominent alterations of cortical neuronal migration and cerebellar Purkinje cells. Neuronal migration, via reelin regulation, requires the intervention of the thyroid hormone triiodothyronine (T3) produced by deiodination of thyroxine (T4) by fetal brain deiodinases. Experimental animal models have shown that transient intrauterine deficits of thyroid hormones (as brief as 3 days) result in permanent alterations of cerebral cortical architecture reminiscent of those observed in brains of patients with autism.

I have postulated that early maternal hypothyroxinemia (low T4) resulting in low T3 in the fetal brain during the period of neuronal cell migration (weeks 8–12 of pregnancy) may produce morphological brain changes leading to autism. Insufficient dietary iodine intake during pregnancy and a number of environmental antithyroid and goitrogenic agents can affect maternal thyroid function during pregnancy. A progressive decline in the levels of iodine in the US population, and in particular among women of reproductive age would increase the population at risk.

Common environmental agents that inhibit deiodinases D2 or D3 include dietary flavonoids and antithyroid environmental contaminants. Some plant isoflavonoids have profound effects on thyroid hormones and on the hypothalamus–pituitary axis. Genistein and daidzein from soy (Glycine max) inhibit thyroperoxidase that catalyzes iodination and thyroid hormone biosynthesis. Other plants with hypothyroid effects include pearl millet (Pennisetum glaucum) and fonio millet (Digitaria exilis); thiocyanate is found in Brassicae plants including cabbage, cauliflower, kale, rutabaga, and kohlrabi, as well as in tropical plants such as cassava, lima beans, linseed, bamboo shoots, and sweet potatoes. Tobacco smoke is also a source of thiocyanate.

Environmental contaminants interfere with thyroid function including 60% of all herbicides, in particular 2,4-dichlorophenoxy acetic acid (2,4-D), acetochlor, aminotriazole, amitrole, bromoxynil, pendamethalin, mancozeb, and thioureas. Other anti-thyroid agents include polychlorinated biphenyls (PCBs), perchlorates, mercury, and coal derivatives such as resorcinol, phthalates, and anthracenes. A leading ecological study in Texas has correlated higher rates of autism in school districts affected by large environmental releases of mercury from industrial sources. Mercury is a well known antithyroid substance causing inhibition of deiodinases and thyroid peroxidase. The current surge of autism could be related to transient maternal hypothyroxinemia resulting from dietary and/or environmental exposure to antithyroid agents. Additional multidisciplinary epidemiological studies will be required to confirm this environmental hypothesis of autism.

Speaker Biography
Prof. Gustavo C. Román MD
Dr. Román was instrumental in the development of currently used criteria for Vascular Dementia (NINDS-AIREN Criteria) and created an international Neuroepidemiology research network that to this day continues to yield data. Dr. Román received the Commendation Medal of the US Department of Health and Human Services (DHHS), and the Distinguished Alumnus Medal from his Alma Mater the National University of Colombia. He is Honorary Member of the neurological societies of France, Spain, Cuba, Panama, Dominican Republic, Venezuela, Austrian Society of Tropical Medicine, Colombian Academy of Medicine and Society of Biological Psychiatry.

Dr. Román was elected Fellow of the American Neurological Association, American Academy of Neurology, American College of Physicians, Royal Society of Medicine (London), and Royal Society of Tropical Medicine (London). He has participated in International Affairs committees of the American Academy of Neurology and the World Federation of Neurology. Dr. Román co-organized twice the International Congress on Vascular Dementia (Geneva, 1999, Salzburg 2002) and was local co-organizer of Vas-Cog 2007 (San Antonio TX, 2007). He was until recently Editor-in-Chief of Neuroepidemiology and he serves in the editorial boards of Journal of the Neurological Sciences, Dementia and Geriatric Cognitive Disorders, Clinical Neurology and Neurosurgery, Revista de Neurología, Neurología, Gaceta Médica de México and is ad-hoc reviewer for numerous medical journals. He has authored and co-authored 16 books, 35 chapters in books and more than 300 journal articles.

Dr. Román is Honorary Neuroepidemiology Professor, Universita degli Studi di Ferrara (Italy) and Honorary President of the Pan American Society of Neuroepidemiology. He served as advisor to the Food and Drug Administration (FDA), and is a reviewer for the Aging Systems and Geriatrics Study Section, and for the Fogarty Center of the NIH. He serves in the DHHS Subcommittee on Inclusion of Individuals with Impaired Decision-making in Research and he is Board Member, World Neurology Foundation. He was recently elected as Trustee to the board of directors of the World Federation of Neurology. Dr. Román is an internationally recognized expert in neuroepidemiology and his current areas of research include the study of environmental factors in stroke and autism.

Dr. Gustavo Román is Professor of Neurology at the University of Texas Health Science Center at San Antonio, TX. Dr. Román trained in Neurology at the Salpêtrière Hospital, University of Paris, France, and at the University of Vermont, Burlington, VT. He was Interim Chairman of Neurology and Neurosurgery (1985-1988) at Texas Tech University in Lubbock and served as Chief of the Neuroepidemiology Branch (1990-1993) at the National Institutes of Health (NIH).
MATERIAL: Go to the Initiative website at www.ehinitiative.org and click on the button that says next teleconference. There you will find the announcement with logistical information and the presentation under “materials” to down load or follow along on your computer.

What are your thoughts on this causation?

-NewsAnchorMom Jen