Thyroid Hormone Disruption and Neurodevelopment


Book Description

Thyroid hormone plays an important role in development and functional maintenance in the central nervous system. Deficiency of thyroid hormone during fetal and early postnatal life induces abnormal development known as cretinism in humans. However, the molecular mechanism of thyroid hormone action has not yet been fully understood. Thyroid hormone action in the brain may be disrupted under various pathological conditions. In addition, environmental factors including endocrine-disrupting chemicals and bacterial endotoxins may disrupt thyroid hormone action in brain, causing abnormal brain development and functional disruption. This is a first book to comprehensively describe the effect of thyroid hormone disruption in the central nervous system. The first section deals with the disruption of thyroid hormone action at the molecular level. First the authors provide a summary of the possible molecular mechanisms of thyroid hormone action in the brain, then they discuss several factors that may disrupt thyroid hormone action. In the second section, animal models to study thyroid hormone action will be introduced. An interesting character of thyroid hormone deficiency is that, without thyroid hormone, the thyroid hormone receptor may act as a “repressor” of gene expression, causing more severe consequence than those of thyroid hormone receptor knockout animals. Thus, several different kind of animal models may be used to clarify the role of thyroid hormone and its receptor in the brain. In the third section, human studies on thyroid disease and neurodevelopment will be introduced. Although endemic cretinism induced by iodine deficiency and sporadic cretinism by various thyroid mutation are well known, the pathophysiological mechanisms that create each abnormal phenotype are not fully understood. ​







Thyroid Hormone Metabolism


Book Description










Iodine and the Brain


Book Description

This volume contains the proceedings of a conference held at the National Institutes of Health in Bethesda on March 21-23. 1988. jointly sponsored by the International Council for Control of Iodine Deficiency Disorders (ICCIDD) and the Fogarty International Center of the National Institutes of Health. Several themes converged to make this meeting timely. The first is an increasing awareness of iodine deficiency disorders as a world-wide problem of public health and a preventable cause of mental deficiency. and as a subject of scientific effort. Increased interest in these problems owes a great deal to accessibility to remote and under developed areas of the world where iodine deficiency persists. As with any subject. greater scrutiny yields unexpected complexity and interest. It is true that provision of iodine. typically as iodized salt, is the necessary and sufficient preventative for iodine deficiency disorders. without including endemic cretinism. This provision is a governmental, economic and social problem. Apart from this, however, the scientific and medical problem of iodine deficiency and its effect on brain development and function is one of great interest and importance for developmental neurology and psychology. Even though the specific preventative agent is known, we do not totally understand the neurobiological questions raised.




Thyroid Hormone in Brain and Brain Cells


Book Description

Thyroid hormone signaling has been known for a long time to be required for proper neurodevelopment and the maintenance of cognitive functions in the adult brain. As thyroid hormone excess or deficiency is usually well handled by clinicians, research dedicated to the neural function of thyroid hormone, have not been a priority within the field. This is changing mainly for two reasons. First, new genetic diseases have been discovered, altering thyroid hormone signaling in brain (THRA, MCT8, SBP2), with neurodevelopmental consequences which are currently incurable. Second, there is a growing concern that exposition of the general population to environmental chemicals able to interfere with thyroid hormone signaling compromises children neurodevelopment or induces central disorders in adults. Finally thyroid hormone is acting directly on gene transcription, by binding nuclear receptors, and therefore is an interesting entry point to identify genetic programs controlling brain development and function. Reaching a broad understanding of the multiple processes involving thyroid hormone in brain is a tremendous task which will necessitate a multidisciplinary approach: animal genetics, molecular biology, brain imaging, developmental biology, genomics, etc... This topic will be the occasion to combine recent contributions in the field and to identify priorities for future investigations. Due to devastating consequences of congenital hypothyroidism, the neurodevelopmental consequences of altered thyroid hormone signaling have been extensively studied over the years. The discovery of new genetic diseases, the concern about the possible neurotoxicity of environmental thyroid hormone disruptors, recently renewed the interest for an important research field. This Ebook gathers reviews and original data from experts in various disciplines. It provides a broad view of ongoing research and outlines key issues for future investigation.




Losing Our Minds


Book Description

The exponential increases in neurodevelopmental disorders implicate both genetic causes and environmental factors. Flame-retardants, pesticides, plasticizers, and other every-day products contain chemicals shown to affect thyroid hormone signaling, which if disrupted can result in significant impairment to IQ. Across entire populations, such effects spell large-scale social and economic consequences. In this book Barbara Demeneix suggests what can and must be done to halt and reverse this disturbing trend.




Medicare Coverage of Routine Screening for Thyroid Dysfunction


Book Description

When the Medicare program was established in 1965, it was viewed as a form of financial protection for the elderly against catastrophic medical expenses, primarily those related to hospitalization for unexpected illnesses. The first expansions to the program increased the eligible population from the retired to the disabled and to persons receiving chronic renal dialysis. It was not until 1980 that an expansion of services beyond those required "for the diagnosis or treatment of illness or injury or to improve the functioning of a malformed body member" was included in Medicare. These services, known as preventive services, are intended either to prevent disease (by vaccination) or to detect disease (by diagnostic test) before the symptoms of illness appear. A Committee was formed "to conduct a study on the addition of coverage of routine thyroid screening using a thyroid stimulating hormone test as a preventive benefit provided to Medicare beneficiaries under Title XVIII of the Social Security Act for some or all Medicare beneficiaries."