There is no doubt that chronic inflammation is a major contributing factor in many of the diseases we associate with getting older. Parkinson’s and Alzheimer’s diseases are inflammatory by nature, and chronic inflammation is a risk factor in diabetes, atherosclerosis and cancer – all conditions that we are more likely to develop as we age.
But why should inflammation leave us so susceptible to increased incidence of these diseases as we get older? In many respects, the answer may be simply that as we age, we slow down – we may become less active, exercise less and gain weight. Chronic inflammation plays precisely into this sort of feedback loop.
The older you are, the more you have been exposed to environmental factors, and past injuries can also come back to haunt us.
“I think inflammation is the great driver of ageing,” says Professor Ian Henderson. We’re all a product of our own history.
“If you’re young and you have an injury, it heals and it doesn’t bother you when you’re 20. It doesn’t bother you at 25 or 30, but when you get to 60 it begins to cause you problems.”
These examples of inflammation occurring decades after the event are also true of infection.
“As you age, your immune system ages too, and you lose control over the inflammatory processes,” says Professor Henderson.
Older people do have consistently elevated levels of inflammatory chemical messengers, especially interleukin-6 (IL-6), which is called into action by the protein response system known as the inflammasome, and tumour necrosis factor (TNF). The suppression of this has proved useful in the treatment of rheumatoid arthritis and other inflammatory conditions.
But higher levels of these chemical messengers are also linked to other factors such as smoking, among many others.
“If you don’t sleep, for example, you become more inflammatory,” says Professor Henderson. “You can connect a lot of the non-infectious diseases to inflammation.”
"As you age, your immune system ages too, and you lose control over the inflammatory processes."
Professor Ian Henderson
What happens as we get older?
- Older people often have high levels of pro-inflammatory markers in the blood and other tissues.
- Some clinical trials suggest that reducing inflammation can prevent cardiovascular diseases, but there are few studies on other chronic diseases of old age and those there are have been inconclusive so far.
- Obesity contributes to age-related disease because visceral fat produces pro-inflammatory compounds that activate the immune system and drive inflammation.
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Dementia and Alzheimer’s disease are the leading cause of death for females in Australia at