Any long-term study that follows people in their old age is bound to lose numbers because of deaths among its subjects, but the Australian Longitudinal Study of Ageing (ALSA) and many of its participants are still going strong.
The Adelaide-based multi-disciplinary study began in 1992 with the collection of data from more than 2000 people with a mean age of 77. Of the 2087 original volunteers for the study, more than 500 remain on the books. They now have an average age of 85, and several participants are over 100.
Mary Luszcz, Professor of Psychology and Gerontology and Deputy Director of the Centre for Ageing Studies at Flinders University, South Australia, said the recent completion of the seventh wave of the study will provide a rich source of data for researchers from disciplines as diverse as psychology and economics, dietetics and medicine.
The National Health and Medical Research Council provided funding to her and colleagues Professor Gary Andrews and Dr Michael Clark for the most recent wave, which Research Project Officers Kathryn Brown-Yung and Mandy O'Grady managed. Detailed information is collected from the participants through face-to-face interviews along with an assessment of general health, which includes tests of cognitive functioning and memory as well as measurements of sight and hearing, balance, blood pressure, and a skin-fold test.
A range of recent research findings based on ALSA data, was presented at the University during a half-day Ageing Research Symposium entitled Twelve Years On: Multi-disciplinary Research from the Australian Longitudinal Study of Ageing. Local and interstate colleagues working with researchers at Flinders presented snapshots of findings from the ALSA.
Dr. Tim Windsor, a collaborator at the ANU, presented data examining factors that determine when elderly participants stop driving. This study of driving cessation, one of the first prospective studies to be conducted in Australia, produced results that were somewhat surprising.
"We didn't find that vision quality per se was a good marker of whether people stopped driving," Professor Luszcz said.
"One bio-marker that was significant was reduced grip strength, which does makes sense - you need a good grip on the wheel to drive and grip strength is a good indicator of frailty."
In this and other analyses more than one or two variables need to be taken into account, Professor Luszcz said.
"ALSA gives us the capacity to place individual questions into a broader context.
"We try to look at a combination of variables all at once, so that you're teasing out what is really operating, and not just finding simple bi-variate relationships which are actually driven by something else that is truly responsible for the effect."
In another study, PhD student Lynne Giles has looked at the benefits attributable to different types of social networks. Families do not come top of the list.
"What she has found is that it is non-family relationships that are most beneficial," Professor Luszcz said.
"For one thing, you get to choose who is in those networks, and these more discretionary or selective relationships are important to well-being.
"Having a confidant may well be more important in relation to psychological well-being, but non-kin relationships have the added dimension of providing variety, an opportunity to exert control over social interactions, and thereby regulate emotions," Professor Luszcz said.
For both survival and disability - becoming unable to walk or balance, to open jars or lift heavy weights - it seems to be that having close non-kin networks (friends, neighbours and other supports) is more important than either your family or a confidant.
"It is usually women that have better networks, and we have evidence that social participation is a factor, apart from biological ones, that contributes to women having longer lifespans than men."
Professor Luszcz said there have been advances in techniques and methodology during the course of the study. Collecting high quality data is of primary importance, she said.
"Because of the age of our participants, it is especially important that we stay in touch with them frequently, without over-burdening them. "If we really want to know about the state of the body or mind, and how that might optimally be maintained or intervened with to extend life or healthy life expectancy, we need to have some norms with which to work," she said.
For instance, Associate Professor Lynne Daniels from the School of Medicine emphasised the importance of having good information on weight, height and other aspects of physique.
Standard measures of Body Mass Index (an index of obesity based on height and weight parameters) can be difficult to calculate in elderly people. Because they are often stooped or sometimes unable to stand, obtaining accurate measurement of height may be nearly impossible.
While measuring knee height has turned out to be an effective indicator of height, it seems that another simple measurement of the upper arm may prove to be more useful than BMI.
Statistics show that obesity remains a threat to health among the aged, and even a small loss of weight has been shown to be beneficial in terms of survival.
Another study in collaboration with Petra Graham of the CSIRO, which examined data relating to cognitive decline in the elderly as predicted by illnesses and treatments for those illnesses, held good news.
"The amount of the decline in cognitive functioning was not very marked, and was not strongly in evidence until after the age of 80," Professor Luszcz said.
"The main lifestyle factors that seem to be important are being socially active and engaged in some exercise as opposed to being sedentary."
Women tended to have less cognitive decline, but for both men and women cognitive decline was related to mortality.
"When medication is related to cognitive decline, there is some protective effect for women related to the taking of aspirin, which increases blood flow to the brain, and also some evidence that calcium channel-blockers, in the absence of hypertension, are beneficial in terms of survival."
Professor Luscz said that analysis of the ALSA data can be drawn on to shape policy as society confronts the many challenges of an ageing population. "It is proving to be an invaluable resource for investigating successful ageing, both at the individual and the collective level," she said.
"Each new wave adds value to the mine of information already acquired and permits us to explore both prospectively and retrospectively the dynamics and diversity of ageing in Adelaide.
"The participants are leaving a generous and lasting legacy for future generations of older people and researchers of all ages."