ANNUAL SYMPOSIUM

Australia's science future 3-4 May 2000
Full listing of papers

Professor Rob Helme graduated in medicine from Monash University. He undertook his PhD on neural control mechanisms at Monash and his clinical training in neurology at the Massachusetts General Hospital. He is a Fellow of the Royal Australasian College of Physicians and the Faculty of Pain Medicine of the Australian and New Zealand College of Anaesthetists. After 10 years in the Department of Medicine at Monash, he became Director of the National Ageing Research Institute in Parkville and Professorial Associate of the University of Melbourne, where his main research interests have been the effects of age on pain, cognition and mobility.

Symposium themes - Ageing

Towards successful ageing: A framework for research
by Rob Helme
r.helme@nari.unimelb.edu.au

Abstract
Ageing or, more appropriately, senescence has been defined as a progressive, generalised impairment of function resulting in an increasing probability of death. The reasons why and how we age are becoming the focus of much discussion and research as most countries realise they have an ageing population. In humans, functional decline occurs at different times in different individuals and in different organ systems; increased variability is a universal feature of older populations. This decline and variability can be attributed to four main factors: the downstream biological consequences of the strategies that have evolved in living organisms to maintain tissue integrity; the effects of diseases associated with ageing that contribute to the morbidity and mortality of older populations; the effects of disuse on most ageing organ systems; and the confounding effects of environment and specific behaviours on cohorts of people as they age. Management of functional decline in older people requires a synthesis of the relative contribution of these factors for each individual. Current knowledge does not permit this analysis, but future ageing research will facilitate this approach to health care.

There is no precise definition of successful ageing. Broadly you could say that it is to keep the deleterious effects of ageing to a minimum while maximising the benefits and ensuring satisfaction with quality of life.

The benefits of ageing include wisdom, leisure time, freedom and being able to send the grandchildren home. I will focus on the deleterious effects.

Of the Australian population, in 1986, 10 per cent were over 65; in 2015, 15 per cent will be over 65. The increase in the over-80 proportion will be much greater.

In England, from the year 1000 to 1900, about 8 per cent of the population were over 60. There has been a dramatic rise in the last century.

The rate of change is even more rapid in developing countries, for example China.

The cost of looking after someone in our health system remains constant until about the age of 65, then rises steeply. Health expenditure in Australia is about 8.5 per cent of gross domestic product, which is less than the USA but more than some other developed countries.

Life expectancy at age 65 in Australia is at the top of the range, 15.7 years. Disability expectations are also quite good by comparison.

Maximum physiological function stays on a plateau before declining; the period of the plateau varies. Marathon world records begin to decline after the age of 30. Ability at mental arithmetic shows a decline in longitudinal surveys, but this may reflect education rather than physiology.

There is a case for treating old people as a higher priority for health treatment, since their reserves are lower than younger people.

The reasons for functional decline with age are:

• biological ageing
• disease
• disuse
• environmental effects.

Most research in developed countries is aiming to increase knowledge of ageing mechanisms.

Session discussion

Productive activity increases vitality. Does depression lead to less productive feelings and suicide?

Julie Byles. Reactive depression is more common among older people. We are still coming to grips with the impact of war-related events on late-life depression.

Rob Helme. Pain and depression particularly affect older age groups.

Stroke is one of the most common causes of disability and yet doctors don’t treat hypertension in older people. That is extremely undesirable.

Julie Byles. One of the problems in treating hypertension in older people is the lag between research results and changes in the prescribing behaviour of doctors. We need a change of view.

Mice with their telomerase template knocked out still aged normally. How do you explain this?

Roger Reddel. They aged normally until the telomeres became short. After six generations the telomeres had become very short, the males were sterile, and there were some signs of premature ageing. However, the role of telomere shortening in the ageing of normal animals needs a lot more study.

How long are the telomeres in cancers?

Roger Reddel. The telomeres of cancer cells can be long or short. But the important point is that the cancer cells are able to keep their telomeres at a fairly constant length. In other words, they avoid the inexorable telomere shortening that occurs during the proliferation of normal cells. In most cases, cancer cells use telomerase to maintain their telomeres, but there is also another process that they can use. So one of the concerns about switching on telomerase in normal cells would be that it increases the risk that they will later become cancer cells. But we could switch on telomerase in normal cells, use them to reconstruct an organ, and then get rid of the telomerase gene. We already have ways to do this.

Burnet started eating zinc sulphate in his seventies. Is it prophylactic for ageing?

Zeinab Khalil. I am not aware of any studies. There is a link between zinc and Alzheimer’s disease.

There has been a study of ageing in women. Is there a study of men’s health in Australia?

Julie Byles. The study was a result of the women’s health movement. A men’s study would require a political decision, with government funding. Men may be quite different, for example, in their need for social interactions.

Rob Helme. Other studies have small numbers and variable outcomes. We need to do some genetic epidemiology in this country.

Studies at the Australian National University have been testing people at intervals of four and five years.

How long do you delay using antioxidants after injury?

Zeinab Khalil. One week.

Does a decrease in calorie intake slow ageing?

Zeinab Khalil. A decrease in calorie intake increases lifespan and decreases oxygen free radicals. It is one anti-ageing strategy. But how many of us could cope with it? Hungry rats lived four years instead of the normal two years.

What happens if you transplant organs from a short-lived species to a longer-lived species?

Roger Reddel. It is hard to predict. The tissue’s proliferative capacity may not be the limiting factor. Immunity may be more important.

Social contact appears to improve old people’s lives. Is there a difference between contacts with young or with old?

Julie Byles. The survey did not show the age of contact. But it is an important point; there is a need for intergenerational contact.

In bees, the workers die young and the queens live a long time. We could try transplants on them.

How does bereavement status affect quality of life?

Julie Byles. For women, quality of life decreases with widowhood but recovers after a couple of years. They manage to reinvent their lives.

Should we take antioxidants before injury?

Zeinab Khalil. There are no studies examining the relationship between long-term intake of antioxidants and tissue repair. Long-term intake of exogenous antioxidants could depress our endogenous antioxidant defence system. It could alter the balance of the internal system.

Are the gender differences in life expectancy due to biological or environmental factors?

Julie Byles. I don’t know. The cliché is women get sick, men die. Women are the greatest users of the health care system. Women’s life expectancy may change as their lifestyles become more like men’s.

What is productive activity?

Julie Byles. Gardening, volunteer work, paid work. No one activity is linked to survival.

Is there telomerase in trees that live hundreds or thousands of years?

Roger Reddel. Those parts of plants that can be propagated long-term have telomerase activity, those parts that can’t be propagated don’t have telomerase.

Rob Helme. Jogging can extend your life by 2 years, but you’ll spend 2 years doing it. You have to
enjoy running.