The question of life expectancy

Why do we grow old and what can we do to stop it? This is the question asked by many, but it appears that we are now closer to an answer thanks to research published by Monash University researcher, Dr Damian Dowling, in an edition of The American Naturalis.

A small set of genes in mitochondria (a membrane-enclosed organelle found in most eukaryotic cells), passed only from mothers to offspring, plays a more dynamic role in predicting life expectancies than ever previously anticipated.

“What we are finding is that natural variation in this diminutive genome results in a huge range of effects on metabolism, mating behaviour and reproductive biology, including male fertility,” Dr Dowling said.

“At the outset of our research program, we suspected that the evolutionary significance of the mitochondria had probably been underestimated by scientists that have come before us, but even we have been continually surprised by the magnitude and ubiquity of the effects that we have uncovered.

“We suspect that this genome still harbours many more secrets awaiting discovery,” Dr Dowling said.

In separate research, gerontologists have argued whether successful ageing is better defined subjectively (how older adults view their own state of ageing) or objectively (physical disease-related disability or mental decline).

Answering this question is more than an academic exercise as the first members of the famed “baby boom generation” reach age 65, understanding what it means to remain healthy and independent in later life could have an enormous impact on health care delivery and medical policy.

Researchers from the New Jersey Institute for Successful Aging (NJISA) at the UMDNJ-School of Osteopathic Medicine have recently unveiled new findings in an article in The Gerontologist that clarify what it means to age successfully, and point to modifiable factors that could help more people remain healthy as they age.

The researchers found that people are more likely to age successfully if they are educated, have never been incarcerated, are married, consume only moderate amounts of alcohol and either work for pay or do volunteer work.

“What you do before age 50 really will generally have the bigger impact on how well you age,” said lead author Dr Rachel Pruchno, who is also the director of research at NJISA.

“Our research shows how ageing is a lifelong process. The person you become at a very old age is really a function of how you lived your earlier years.

“Education and incarceration were particularly strong factors,” Dr Pruchno said.

“The fact that we currently have a large number of people in prison serving relatively short sentences could herald a significant public health problem in the future. Interestingly, although marriage also coincided with successful ageing, being childless did not appear to have a negative impact.”