PerspectivesAre you interested in submitting a Perspective Article? Be sure to read The Science Advisory Board's Editorial Guides for Perspective Articles. Click here. Ageing: Consequences and Responses by Tahira Farooqui, Ph.D. Research Scientist Department of Entomology The Ohio State University 1. Ageing Ageing in animals refers to a progressive functional impairment leading to mortality. Many theories of ageing have been proposed, but the biological mechanisms that underlie ageing are still unknown. Major theories of ageing concern altered proteins (Levine and Stadtman, 1996), DNA damage and DNA repair (Harley, 1991), inappropriate cross-linking of proteins, DNA and other structural molecules (Bjorksten, 1974), failure of neuroendocrine secretion (Mobbs, 1996), cellular senescence in cell culture systems (Hayflick and Moorehead, 1965), increase in free radical (oxidative stress) generation (Harman, 1981), and change in the order of gene expression (Helfand and Rogina, 2000). While no single theory accounts for all aspects of ageing, recent research suggests that the primary ageing process is under genetic control, with contributions from environmental factors (Robert and Labat-Robert, 2003). Any ageing theory must be able to answer two basic questions: (1) Why and how does the ontogenic development end with a progressive and functional deterioration? (2) Why is the time axis of the ontogenic development (life span) so different among various animal species? A widely accepted concept is that the pattern of ontogenic development within each species is genetically determined (Zs.-Nagy, 1997). Therefore, one possibility is that ageing may be genetic, resulting in a gradual deterioration in molecular components (e.g. loss of code, loss of gene expression devices, loss of conditions for gene expression, and/or improper gene regulation). These components must function in a concerted manner in order to support cell viability and proliferation (Zs.-Nagy, 1997; Meshorer and Soreq, 2000). Decreases in the efficacy of DNA repair (Barnett and King, 1995), of the role of telomeres (Allsopp et al., 1995), and of mitochondrial DNA deletion (Ozawa, 1995) have all been reported to occur with ageing. The decline in these components may also be related to cellular senescence, apoptosis, and ageing-associated pathologies. 2. Ageing, diseases, and learning In humans, ageing leads to the accumulation of disabilities and diseases (such as diabetes, heart disease, cancer, and arthritis) that limit our normal body functions. Berzlanovich et al. (2005) evaluated 42,398 consecutive autopsies over a period of 18 years at the Institute of Forensic Medicine, Vienna. This study reviewed age, sex, circumstances of death, season, time, and the cause of death, as well as the presence of any other comorbidity in centenarians (those 100 years or old). Researchers indicated that 60% of centenarians were found to be healthy prior to death. However, in all of them, death was due to an acute organic failure (cardiovascular disease in 68%, respiratory illnesses in 25%, gastrointestinal disorders in 5%, and cerebrovascular disease in 2%). Comorbidities found in these subjects were not the cause of death (Berzlanovich et al., 2005). Understanding the underlying mechanisms for such a complex process -- “ageing” or “age-related diseases” -- will be useful for the development of new strategies for treating various age-related problems. Learning is one of the processes of memory by which the brain adapts to changes in environmental input (Agranoff et al., 1998). However, memory is defined as the persistence of learning over time, through the storage and retrieval of information. Thus, memory includes: (1) learning or encoding, (2) short-term or long-term storage, and (3) recall or retrieval. Therefore, if we test recall, it will tell us what we learned. Thus we can not consider learning without memory or memory without learning. Although age-related learning deficits occur in the elderly, ageing does not stop the learning process in healthy individuals. Older individuals have to keep learning in order to stimulate the brain. If one stops learning, the brain will start losing neurogenesis, resulting in mental problems. So even though we keep growing old, we should keep learning. Thus the proverb “use it or lose it” seems to hold true. 3. Ageing model systems It is difficult to study ageing in human subjects for several reasons: (1) with age, humans become more susceptible to diseases, increasing the difficulty in finding healthy subjects, (2) in vivo experiments are impossible, (3) due to the longer life span of humans, it would take decades to complete the project, and (5) the researchers would be limited in performing the planned experiments because they themselves would be ageing. Therefore, we use a model system, which allows researchers to do in vivo and/or in vitro studies. The information obtained can then be applied to human ageing. The selection of a model system for ageing studies is a highly controversial issue, because although the physiology of the model system selected may be different from human physiology, it can still help in understanding the mechanisms of human ageing. The yeast (Saccharomyces cerevisiae) has been used as a model for ageing (Jazwinski, 2001). In addition to mammals, several invertebrate model systems are now available for ageing research. Invertebrate model systems have advantages over vertebrates because they are less expansive and have a shorter life span. The fruitfly (Drosophila melanogaster) with a life span of 2 months has been successfully used as a model to identify genes associated with ageing and/or longevity (Parkes et al., 1998; Yui et al., 2003; Orr et al., 2003). Soil nematode (Caenorhabditis elegans) has a life span of 1 month, and is an excellent model organism for studying the ageing process (Houthoofd et al., 2005). The use of honeybee (Apis mellifera) may also work as a potential insect model for ageing, particularly in regard to olfaction: (1) because of anatomical and physiological similarities in the neural network of the antennal lobe to the vertebrate olfactory bulb, (2) their ability to learn about the association of odor with reinforcement, (3) well established behavioral paradigms for olfactory learning, (4) short life span, and (5) availability of its genome sequence. Furthermore, a distinct advantage of using the honeybee as a model for ageing over other insects is their social organization, behavior, and the analogous ecological problems (like humans) they face during ageing that require olfactory learning. 4. Ageing: can it be delayed? Although we cannot control ageing in our lives we can certainly learn to stay healthy and delay ageing by practicing the following: (1) Decrease stress: Learning how to manage the stress on our bodies is the first step towards delaying ageing because our emotional health is closely linked with our physical health. We cannot always change what happens to us but we can certainly control how we react to these changes. (2) Nutrition: The old saying “you are what you eat” is true. If we watch what we eat and how much we eat (caloric restriction), we can help slow the ageing process. (3) Planned exercise program: Exercise helps in controlling weight, glucose levels, and blood pressure. It also elevates high density lipoprotein (HDL, good cholesterol) levels. (4) Medications: Take medications on time as directed by your Physician. (5) Find someone you can talk with: Sometimes a good listener (your spouse, friend, coworker, and/or health professional) can be a blessing because they can help you to think positively. (6) Make friends: Irwin Sarson said: “Good friends are good for your health.” I think we can all agree with this statement. Share your ageing experience with friends and try to make it worthwhile. (7) Keep yourself busy: Do something creative. Involve yourself in meaningful activities. Instead of watching television, spend time in volunteer work. Involve yourself in horticultural therapy such as gardening. You will feel good and feeling of loneliness will go away if you stay busy. (8) Positive attitude: Psychological state of mind directly affects the ageing process. Having a positive attitude in life is very important. Learn to accept the facts of life. Just because you do not like them, you cannot change them either. (9) Sense of humor: It is very important to share laughter. Imagine life without humor. Wouldn’t it be dull and boring? If no one is around then try to laugh at yourself. Think about the mistakes you have made in past. Watch some comedy movies. Laughter is one of the best medications you can provide to your body. It will help you coping with everyday life’s challenges. Using humor will decrease stress and you will feel light, healthy and good. We should think about what Billy Graham, an American Evangelist wrote: “A keen sense of humor helps us to overlook the unbecoming, understand the unconventional, tolerate the unpleasant, overcome the unexpected, and outlast the unbearable.” 5. Ageing with dignity In modern times, average life span and life expectancy have grown dramatically due mostly to improvements in sanitation, the discovery of antibiotics, and medical care. Several non-profit organizations are available which are running on charitable contributions and provide care to elderly. We should plan in advance and save money for our old age and/or for serious illness, so that we don’t become a burden on family members or friends. Planning can ensure that we get the care we deserve during the critical time toward end of our lives. 6. Anti-ageing medicine Anti-ageing medicine (active prevention) does not stop or reverse the ageing process. By recognizing and decreasing the risks of developing chronic diseases provoked by genetic disposition, lifestyle, and biochemical changes, one can elaborate preventive strategies (Wolf, 2005). Some of these anti-ageing treatments and products are actually ineffective and can seriously harm consumers (Mehlman et al., 2004). Therefore, geriatricians and gerontologists have to be more aggressive in providing educational efforts to protect older consumers. Several age management programs are available that provide no scientific proof of their medical benefits, but still attracts consumers. Both consumers and providers should be aware of the legal issues associated with the current and future use and practice of anti-ageing medicine (Reisman, 2004). 7. Conclusion Many theories of ageing have been proposed over the years and no single theory accounts for all changes that occur in ageing. While it is a multifunctional, complex and inexorable process, precisely defined markers for this process are missing. An increased susceptibility and vulnerability to diseases in old age in humans may be due to a decline in physiological functions and a decrease in the ability to cope with oxidative stress. The ageing field is exploding. Researchers have demonstrated the role of several genes that influence longevity. The goal of researchers should not be to evaluate how to enhance human longevity but to determine how to remain active and have a disease free life (healthy longevity) during ageing. We cannot say that longevity is same as ageing. 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J Mol Med 75:703-714. ### << Previous Next >> [ View All Perspectives ] |
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