Health Implications of Chemicals and Pharmaceutics in an Aging Population
Figure 25.1 Proposed schematic diagram of the impact of the aging process due to endogenous and exogenous changes. The oval shape infers that the aging population is encountering endogenous changes, which has an impact on the aging process. All of the exposures occurring outside the oval but inside the rectangle will contribute to the exogenous changes and their associated impact. To investigate all these issues, we performed a thorough review of the impacts of xenobiotics (including chemicals and pharmaceuticals) in the aging population, including the older adults and elderly, for relevance to the association between diseases/changes in the aging population and exposure to environmental agents or pharmaceuticals. This includes epidemiological studies, case studies and experimental researches. We also briefly reviewed genetics, lifestyle habits (e.g., smoking, alcohol) and other potential risk factors, whenever evidences are available. In response to the commitment of evidence-based practice, we tried to search different levels of literature and evidence as much and as comprehensively as possible. Here, we realize the limitations and gaps of available scientific information that discusses age-specific issues and their
effects on xenobiotic agents toward the aging population, as toward the other age groups . Some studies varied in sample size, had selection biases, or had some other shortcomings. While the level of stringency of study design and definition among the studies varied, some are in the lower levels of evidence, that is, in vivo and in vitro studies. Therefore, it is known that there are some disadvantages when adapting information from the findings of animal models, in addition to in vivo and in vitro studies, to extrapolate the findings to aging related changes, such as cognition and pathology of humans . Some information and content are in conflict and vary from data to data. To address the diversity and variations in the quality of the database, we have assembled a team that includes clinical pharmacists, geriatricians, nephrologist and pharmacologists from Taiwan who worked collectively on this review. In this chapter, we (1) first describe the different aspects of potential changes occurring among individuals of the aging population; (2) focus on exposure to chemicals, pharmaceuticals, herbs and dietary supplements (also known as xenobiotics) in the aging population; and (3) discuss the impacts on this population of multiple exposures to xenobiotics, mainly in terms of adverse health consequences. 25.2 Biological, Physiological, and Functional
Changes Aging is a normal biological process in humans and usually involves gradual changes of the body’s structure, function, and/or ability to adapt to environmental stress and exposure to xenobiotics. Intuitively, the effectiveness of various physiological functions begins to decline from middle age and there are more observable and measureable changes at around 55-60 years. However, physiological, biological, and functional aging do not necessarily occur at the same speed across individuals and all of these changes could be dynamic. It is difficult to distinguish the reasons for the decline in physiological, biological and functional activities among the aging population because the aging process results not only from advancing age and changes in biological and physical activities, but also occurs as a result of the combination of diseases and other factors.