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Feature: Understanding the ageing body

Winter 2010

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A new transatlantic research collaboration is set to further our understanding of why people become more susceptible to a catalogue of conditions as they get older.

In the past, hitting pensionable age meant joining the elite category of ‘old’. In recent years the extent of longevity in the developed world has increased significantly. This has led to the UK Office for National Statistics (ONS) adopting a new category of ‘oldest old’ for those aged over 85. Last year the ONS predicted there were 1.3M over 85s in the UK, and that this figure will double over the next 25 years, with this age group making up 5% of the population.

However, increasing quantity of life brings with it serious quality of life issues. In the UK, 40% of over 65s suffer from a long standing illness or disability, this increases to 56% in the over 75s and to 69% in the oldest old (ref 1).

In the first agreement of its kind, BBSRC and the US funding agency for ageing research, the National Institute on Aging (NIA) have recently announced joint funding for 6 projects being carried out by leading researchers in the UK and the US to study the biology that drives how our bodies change with age.

The funded projects cover a diverse range of areas including modelling work in molluscs to preclinical studies in the thymus.

Question of immunity

In the UK, people aged over 65 make up three quarters of NHS patients (ref 2). A considerable factor in older people’s ill health is their reduced ability to deal with infections due to lower immune system function – referred to as immunosenescence. Science has not yet provided all the answers for why the immune system declines with age, but researchers from the University of Edinburgh and the University of Georgia are looking to the thymus for crucial clues.

The thymus, situated in the upper chest, plays a central role in the immune system as it is needed for T-lymphocytes to develop. These white blood cells are responsible for cellular immune response. However, the thymus degenerates with age – a process termed thymic involution – meaning that fewer new T-cells are produced.

Dr Clare Blackburn, lead researcher from Edinburgh explains, "The mechanisms underlying this process are poorly understood. We know that the thymus is one of the first organs to degenerate in normal healthy individuals, which has a number of consequences including increased susceptibility to infection. We also know that hormone levels in the body have an impact on degeneration and regeneration of the thymus, but we don’t know how."

It is the ‘how’ that Dr Blackburn and colleagues intend to find out over the next 3 years, by identifying the mechanisms by which steroid hormones called androgens, affect the thymus.

"We have generated tools that will allow us to test how sex steroids affect the thymus," says Blackburn. "We are now at the point of beginning those specific experiments."

She hopes their work will help develop better strategies for reversing thymic involution and, consequently, improving immune system function in the ageing population and other immunocompromised patients.

Under the sea

Marine biologists Professor Chris Richardson and postdoctoral researcher Dr Iain Ridgway are taking a seemingly unconventional approach to gain a better understanding of the ageing process. He and his team from the University of Bangor’s School of Ocean Sciences, have been studying clams to develop a new model organism for ageing research.

"Bivalve molluscs, such as clams, scallops and oysters have been virtually ignored by ageing researchers," explains Professor Richardson. "These creatures span an enormous range of longevities, unheard of in other animal groups, from less than 1-year in one species to over 400 years in the ocean quahog."

Classical model organisms such as fruit flies and rodents have so far played an important role in our understanding of the ageing process but, highlights Professor Richardson, they have been chosen primarily for convenience rather than for specific features pertinent to human ageing.

"An alternative approach, taking advantage of the astounding diversity of ageing rates prevalent in nature is a comparative investigation of short lived, poorly ageing species with other long lived species that age slowly," Professor Richardson explains. The perfect example of this is the Ocean Quahog."

Professor Richardson and Dr Ridgway will spend the next 3 years working with Professor Steve Austard and his team of gerontologists from the University of Texas Health Science Centre investigating the mechanisms behind the exceptional longevity displayed by the ocean quahog and how these mechanisms might advance our understanding of the ageing process in humans.

Quality control

Whether in humans or models, the findings from these six projects will play an important part in developing treatments, strategies and further research to ensure that becoming old, or oldest old, is not simply a matter of endurance, but a quality time of life too.

The context of ageing

• Fractures in people aged 65 and over are responsible for more than 4M bed days each year in England
• Half of elderly people with hip fractures never regain their former level of function and 1 in 5 dies within 3 months
• 1 in 3 people who die aged 65 or over have dementia
• 90% of strokes affect people aged over 65. (Source: Age Concern Fact Sheet)

(Source: Age Concern Fact Sheet)

References

1. Family Resources Survey, 2007/8
   Department for Work and Pensions, 2009
2. Based on Health Development Agency Annual Report 2005, cited in ‘Older people in the United Kingdom,’ Age UK, 2009

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