Biological Age and Osteoarthritis
Published in Annals of Rheumatic Disease, August, 2006
At the end of every strand of DNA is a segment called the telomere that does not code any genetic information but serves as a buffer zone for the coding section of the DNA. Every time a cell replicates, the telomere becomes slightly shorter. Environmental factors that affect replication rate, such as inflammation and oxidative stress (a medical term for damage to cells caused by an imbalance of pro-oxidants and anti-oxidants, also affect telomere length over time. Therefore, telomere length is an indication of age and damage, yielding a person’s “biologic” age.
Useful Definitions
Statistical significance: A result that is unlikely to occur by chance alone is termed statistically significant. In clinical research, a significance level of 5% or lower is generally what is considered statistically relevant. That means that the result being studied would happen less than 5% of the time by chance, but would have a 95% or greater chance of having been related to the effect being studied.
Kellgren/Lawrence scale: A method of scoring and grading x-rays for the presence of osteoarthritis based on the degree of osteophyte (bone spur) formation, joint space narrowing, sclerosis (changing of the bone tissue around the joint), and joint deformity. In this scale, 0 = normal; 1 = doubtful OA; 2 = minimal OA; 3 = moderate OA; and 4 = severe OA.
Osteophyte: Bony projections that form along joints, often associated with osteoarthritis. Also called bone spurs.
In a recent issue of Annals of the Rheumatic Diseases, researchers from St. Thomas’ Hospital in London, University of Medicine and Dentistry of New Jersey in Newark and Boston University School of Medicine reported results of a study examining the telomere length in white blood cells of people with hand osteoarthritis compared to people without osteoarthritis.
They took hand X-rays and drew the blood of 1,086 volunteers. The telomere lengths of leukocyte cells (white blood cells) were measured and compared. Subjects with hand osteoarthritis had substantially shorter telomere lengths than those without. Even after adjusting for potential confounding factors, including age, sex, body mass index and smoking status, the difference was still statistically significant. Furthermore, telomere length significantly decreased with an increase in osteoarthritis scores (total Kellegren/Lawrence score, total osteophyte score, and total joint space narrowing score).
According to lead investigator Guanju Zhai, PhD, “leukocyte telomere length is associated with hand OA and telomere length reduces with increasing disease severity, suggesting potential shared mechanisms between osteoarthritis and aging, and implicating acquired factors, such as oxidative stress and low-level chronic inflammation, in both conditions.” Relieving oxidative stress and chronic inflammation could have an impact on cellular aging and the development of osteoarthritis.
