Osteoarthritis, a degenerative and debilitating inflammation of the joints, may be a sign that sufferers are ageing more quickly than healthy people of the same age, a new study suggests.
Guangju Zhai, Tim Spector and colleagues at St Thomas鈥� Hospital in London, UK, looked at telomere length 鈥� a measure of relative ageing 鈥� in the white blood cells of over one thousand people. They found that those with osteoarthritis had shorter telomeres and were an average of 11 years 鈥渂iologically older鈥� than non-sufferers of the same age.
Telomeres are caps on the end of chromosomes made up of multiple repeats of 鈥渘onsense鈥� DNA. Every time a cell divides, the telomeres become a little shorter, providing a convenient way to measure the relative age of a cell. When the telomeres have shortened to nothing, the cells can no longer divide and they die. This is part of the natural ageing process .
Advertisement
Many factors can make telomeres shorten, such as genetics or the damage caused by oxygen free-radicals. These are toxic chemicals produced as a by-product of metabolism or by other factors, including tobacco or sunlight. Smoking and obesity have both been shown to make telomeres shorten more rapidly.
Expectations confirmed
To test whether there was a link between the rate of ageing and osteoarthritis, Spector and his team took a group of 1100 people, mostly female twins, and used hand X-rays to test for osteoarthritis. They also tested for telomere length in the white blood cells of the participants.
As expected, the researchers found that the older the people, the shorter the telomere length. However, in 160 of those found to have osteoarthritis, telomere length was significantly shorter than those that did not have the disease.
The results persisted even when other factors such as age, sex and smoking were accounted for. In addition, telomere length was found to be even shorter in more afflicted sufferers of the joint-swelling disease.
鈥淚t seems that osteoarthritis and the more general degeneration associated with ageing share some common mechanism,鈥� Zhai told New 杏吧原创. Environmental factors such as oxidative stress 鈥� caused by smoking or obesity, for example 鈥� and inflammation could be implicated, he suggests.
Multiple link
鈥淚t鈥檚 an interesting study,鈥� says Jane Worthington of Manchester University鈥檚 Arthritis Epidemiology Unit in the UK, which adds to the growing list of conditions that have been linked to telomere shortening.
These include dementia, osteoporosis, atherosclerosis and heart disease. 鈥淗owever, it鈥檚 difficult to conclude from this study if the observed effects are explained by genetic or other factors,鈥� she adds.
Osteoarthritis is the most common form of arthritis and usually strikes in old age. Its causes are unclear, though genetics, occupations that increase stress on the joints, and other factors such as smoking and obesity have all been linked to it.
Osteoarthritis can sometimes strike younger people, such as sportsmen and sportswomen, but in these cases, it is more likely to be due to direct damage to the joints.
Journal Reference: Annals of the Rheumatic Diseases (DOI: 10.1136/ard.2006.056903)
