MAINTAINING FUNCTION WITH AGING WHAT WE HAVE LEARNED FROM THE FELS LONGITUDINAL STUDY.

The International Academy on Nutrition and Aging (IANA) will host an important symposium “Improving and Maintaining Functions with Aging” in Albuquerque, New Mexico next July 12th and 13th. This biennial meeting is conducted in collaboration with the International Association of Gerontology and Geriatrics and the Gerontological Society of America. The topic of the 2012 symposium is of considerable importance for the quality of life of older adults and the sustainability of their healthcare: “Improving and maintaining functions with aging”. The abstracts included in this issue of the Journal of Frailty & Aging to be presented at the IANA meeting are particularly informative. They especially provide an interesting continuation of the discussion about frailty as a multifaceted syndrome of older adults. These ongoing works are extremely promising and may represent an excellent resource for the investigation of frailty and the aging process. The topic of the 2012 IANA meeting is particularly relevant because the world population is aging. This demographic phenomenon is at the basis of major challenges in planning and putting in place dedicated healthcare services and treatments. The demographic shift in the age distribution of the world population is not new. It has been forecast for decades, and our efforts to manage its impact within communities, societies and countries have become a critical ongoing process. For developed countries, the aging of the population is already a fact, while coutries under development will face its consequences in the next few years. For these reasons, the study of the physiological, biochemical, psychological, social and health mechanisms underlying the aging process represent major priorities to be addressed. There have been relatively few long-term comprehensive studies of the aging process until recently, and most of them are characterized by a short duration of follow-up. In fact, in this field more than in others, several conceptual and methodological problems arise, significantly affecting the development of research studies. Questions like “when does old age begin? ”, “is it the same for everyone?”, “what is the distribution of aging characteristics and diseases at old age?”… often impair our capacity to globally and comprehensively understand the aging mechanisms. For example, it is noteworthy that all of these cues are affected by a variety of social factors (including education, nutrition, social status, availability of healthcare) and the recruitment of minorities is scarce. The availability of studies attempting to address such important age-related issues is limited. Aging is a multidimensional process, and an evaluation of it restricted in a limited timeframe may result in partial and potentially misleading results because of the lack of the appropriate context. During the past 20 years, several large scale studies of aging have been conducted to cover one or two decades of follow-up. Studies of aging having a follow-up of longer than two decades are few. In particular, we can mention the Framingham Heart Study (http://www.framinghamheartstudy.org), the Baltimore Longitudinal Study of Aging (BLSA, http://www.grc.nia.nih.gov/branches/blsa/blsa.htm), the New Mexico Aging Process Study (1), and the Fels Longitudinal Study (2). The BLSA and the New Mexico Aging Process Study were specifically designed as aging studies. Differently, the Framingham Heart Study began as a project on cardiovascular conditions, and the Fels Longitudinal Study was aimed at exploring child growth and development. Among these four and in comparison to other similar studies, the Fels Longitudinal Study is the longest in continuous operations, having started in 1929. With recruitment occurring “in utero”, the oldest participant will be 83 in 2012. Due to its longitudinal design, the number of Fels participants at any age is small, but the number of participants is cumulative as the years pass and they are getting older. To date, 64 participants (30 men and 34 women) with long-term records from birth to their current age (ranging between 70 and 82 years) are currently part of the Fels Longitudinal Study. The serial data of these few healthy participants (stratified by sex) indicate interesting trends for weight, body mass index (BMI), fat-free mass (FFM) and total body fat (TBF), potentially explaining the pathways leading to frailty (unpublished data). Recording the body weight of participants since 20 years of age has demonstrated a peak at 65 years of age (men: 100 kg; women: 75 kg). Then, body weight begins to decline (by about 20–25 kg) in both men and women by the end of the seventh decade or about 15 years later. Differently, FFM peaks in the mid- to late-thirties in both men and women, and tend to decline continuously afterwards with a larger negative slope in women. On the other hand, TBF peaks at about 50 years of age in women and later (at about 65 years of age) in men; then, and it starts to decline in both at about 70 years of age. Interestingly, the evaluation of BMI has not particularly shown informative results. It is noteworthy that adult Fels participants are representative of the United States population with same age and corresponding levels of income, education and health. These preliminary body composition data indicate that some of the potential contributors of frailty start to be altered in middle age, supporting the need to monitor the ongoing process of aging. In other words, the onset of frailty is not characterized by a sudden appearance, but by a gradual accumulation of declines in body systems. Thus, for example, if the FFM of an individual rapidly declines due to inactivity, this may increase his/her risk for the onset of frailty, at an early age. However, the patterns of change in body composition and the variance of composition within populations of older adults worldwide are still poorly understood, and that paucity of knowledge is particularly worrying for the health assessment and treatment of those at older ages.