DHEA in Human Health and Aging PDF

Preface

Dehydroepiandrosterone (DHEA) and its sulfate ester are secretory products of adrenal glands. They are the most abundant hormones in the systemic circulation of humans, convertible into androgens and estrogens in the periphery with the potential to act alone or through their estrogen end products. Based on their abundance and reduced production during the frequent diseases of aging, they should be critical to many aspects of health. Therefore, DHEA is commonly used in the United States and some other countries as a nutritional supplement for antiaging, metabolic support, and other uses. Yet, substantial mystery exists about the role of low levels of DHEA in seniors when chronic disease states are prevalent. While animal studies clearly show substantial benefits to DHEA/DHEAS supplementation in reducing cancer growth, AIDS progression, and other physiological dysfunctions, these are only partially defined for humans. A major goal of this book is to document the role or lack thereof for DHEA and its reduced presence as well as supplementation on human physiological dysfunction.

DHEA and DHEAS are steroids synthesized in human adrenals and in the brain, further suggesting a role of these hormones in brain function and development. Despite intensifying research, many questions concerning their mechanisms of action and their potential involvement in illnesses remain unanswered. The endocrine system, specifically the hypothalamus–pituitary–adrenal axis, plays an important role in modulating immune function. With aging, an imbalance occurs between two adrenal hormones, cortisol and DHEA, that have opposing actions on immune function. There is continuing controversy on whether DHEA treatment benefits adrenal-deficient and elderly people with an age-related decline in DHEA and its sulfate ester. Available studies have demonstrated beneficial effects of DHEA on health perception, vitality, fatigue, and (in women) sexuality. DHEA restores low circulating androgens to the normal range in women, and side effects are mostly mild. DHEA may affect production of Th1- and Th2-associated cytokines, suggesting their significance in diseases in which imbalanced lymphocyte activity plays the essential role. DHEA's decline with age makes it an interesting marker for many diseases of aging, and it has been tested extensively as a supplement to restore DHEA levels, thus changing disease and disease risks. However, how many therapies and benefits can be supported by research? How successful are DHEA levels in predicting risk of disease? Individual authors review such questions as they describe DHEA's role and changes in humans.

This edition has a unique focus on the role of DHEA in human health. To accomplish this goal, the editor selected authors who are researchers with experience in studying the role of DHEA deficiency and supplementation in various diseases and physiological states in humans.

This book is a comprehensive set of reviews on the biology of DHEA relevant to human health. The origin of circulating DHEA and adrenal-derived androgens in humans and nonhuman primates is largely distinct from other mammalian species. However, there is a section of potential future uses of DHEA, focusing on model studies that have not or cannot yet be done in humans. There are numerous areas with clinical potential importance and varying levels of study that will be related to low DHEA with age or physiological changes and their impacts on health.

In addition, DHEA is widely available as a dietary supplement in the United States and some other countries. Thus, the sections focus on prevention as well as treatment of various human disease states by changing DHEA levels. Often, the role of DHEA is still controversial in certain human health conditions, and the researchers help define what is known for the various conditions being treated. The book will also have some overview chapters on age-induced deficiency, supplementation for aged women, and the role of therapy for aging. Prevention of disease with DHEA includes diabetes, fitness, infectious disease, cancer, AIDS, bone health, and cardiovascular diseases. Treatment covers some similar areas, with autism and mental health being important additions. Animal model information is included as needed to help understand studies done in humans. An important area will be reviews of the effects of loss of adrenal gland function and the subsequent reduction in DHEA production and of its replacement as a therapy. DHEA is one of two hormones sold over the counter as a dietary supplement, and it is thus readily available to consumers in many countries.

Finally, a group of chapters reviews mechanisms of action of DHEA in human diseases including prostate and ovarian health, vascular modification, and adverse effects in DHEA-supplemented women, and finally, stress, memory, aggression, and Alzheimer's disease. The book should be of extensive interest to gerontologists, physicians, physiologists, biologists, public health workers, and biomedical researchers.