Here I'll point you to a discussion paper published last month on the topic of whether or not aging is a disease: it is on the whole eminently sensible and well worth reading, and it is a pity that the vast majority of the people who would most benefit from looking over this paper will never even notice that it exists.
In recent years a large amount of ink has been spilled in the debate over whether or not aging should be either colloquially or formally defined as a disease, although this is a discussion almost entirely restricted to the scientific community, invisible to the world at large. As I've noted in the past this really wouldn't matter all that much, save for the fact that medical development and provision of medicine is heavily regulated. In countries like the US it is literally the case that everything to do with medicine that is not explicitly permitted and on a list somewhere at the FDA is by default forbidden and illegal. Treating aging is at present not on that list - and even some conditions of aging such as sarcopenia are not yet on the list, despite years of lobbying. The wheels move exceedingly slowly.
Thus underlying any debate over what exactly we mean by disease and what exactly we mean by aging is the fact that funding and the pace of progress in aging research rests on which boxes are checked by various bureaucrats. Powerful incentives steer those who work within the regulatory straitjacket, and changing the use of language to better move with the imposed limits is almost the least of harmful outcomes. Still, there are other reasons to argue for aging to be called a disease, such as clarifying the position of the research community for the layperson, and aiming for greater support for the goal of bringing aging under medical control.
Is our understanding of aging still in the dark ages? Over the course of the last centuries a gradual process of enlightenment has taken place in many different areas of human understanding, in which traditional views have been overturned by new knowledge borne of reason and the results of scientific investigation. A more realistic view of things, though it can initially cause controversy by upsetting traditional views and practices, ultimately enables more effective and more ethical action. Such a process of rationalization has profoundly affected the field of medicine, and the way we view many health-related issues. Yet when it comes to aging this salutary process of rationalization is still in its early stages. Here a salient example is the widespread and, arguably, false view that aging is distinct from disease and therefore not appropriate for medical attention - and even something benign and wholesome.
I have encountered many erroneous views during my 20 years working as a biogerontologist, often from members of the public but also from clinicians, gerontologists, and academics of various other specialities. A particular source of error is the false dichotomy drawn between aging and disease. When biogerontologists speak of aging they usually mean senescence. Is senescence a disease? The very word senescence, denoting deterioration leading to death, certainly carries that implication. If senescence is an evolutionary adaptation, this would to some extent support the idea that aging is non-pathological. But this reasoning would also involve a fallacious appeal to nature, a false equation of human evolutionary fitness with well being. If human aging did in fact evolve to benefit the species by ridding it of worn out elderly people, this should not deter us from looking for treatments for Alzheimer's disease and cancer.
Is aging distinguishable from pathology? Given the similarity in meaning between disease and pathology, asking this is similar to asking whether aging is a disease. It has been concluded that there is no clear distinction between aging and pathology, and this is supported by accumulating evidence from biology. Treatments that extend lifespan in animal models typically delay age-related pathology and extend youth span: life extension only occurs as the result of prevention of pathology, whether the pathology is caused by aging or by something else. Life extending treatments in the laboratory invariably decelerate aging (rather than stopping or reversing it); this results in a delay in the appearance of age-related pathology (extending youthspan), but then such pathologies still eventually appear, causing illness, and death.
A goal of preventing diseases of aging without altering aging itself makes little sense if aging itself is pathological, though it certainly makes sense to prioritize action against the more lethal pathologies. In a similar vein, the likelihood of recapitulating Tithonus's dreadful fate is very remote; in fact, to my knowledge no biogerontologist has ever generated a worm or fruitfly Tithonus in which life in a state of advanced senescence is greatly extended. Finally, the goal of enabling people to die without pathology, or of pure aging, is untenable if non-pathological senescence does not exist. In fact, the idea of elderly people dying of aging without pathology is plainly nonsense; among the defining properties of pathology, causing death is surely a sine qua non. (Yet I recently discussed with a former director of a major medical research funding agency the idea that elderly people can die without pathology, and found that they agreed with it).
It seems likely that advances in biogerontology will contribute to geroprotective interventions which hold back the pathologies of human aging; such interventions may well increase lifespan. A recurrent feature of arguments against treating aging is an over-emphasis on increased lifespan as an outcome, and neglect of alleviation of illness. Thus, to say: "I would like a longer life" may be presented as egoism or folly, but not "I would like to remain free of cancer." Likewise, one would not hold against someone infected with, say, malaria their wish not to die from the disease - and one would certainly not accuse them of egotism for wishing to extend their life. The point here is that, in the end, senescence is in many ways just like other severe diseases: it causes illness and death, and treating it results in a longer life. Critics of treating aging are often guilty of double standards, and of undervaluing the well being - and life - of older people.
To act ethically a realistic grasp of relevant facts is critical. This is particularly important for aging, the main cause of chronic disease and death in the world today. Yet traditional ideas about aging include some major misconceptions, including the aging-disease false dichotomy. It is to be hoped that such ideas do not misguide those responsible for the healthcare interests of older people, including those responsible for setting medical research priorities. Neglect resulting from misunderstanding aging may cause harm by allowing preventable illness, both now and in the future - given that geroprotection is most efficacious in the form of prevention. To achieve the best outcomes in terms of the future health of older people, it is vital to adopt a frank and rational attitude to aging. We must draw aside the rosy veil of tradition and face aging for what it is, and in all its horror: the greatest disease of them all.