Friday, September 20, 2013

Telomere length linked to fibromyalgia pain

Source: PainMedicine News
September 21013, #11
Date: September 16, 2013
Author: Michael Vlessides


Telomere length linked to Fibromyalgia pain
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Washington - Considered a marker for biological aging linked to
increased risk for morbidity and mortality, shortened leukocyte
telomere length now has been associated with pain in fibromyalgia,
researchers at the University of Michigan have found. The
investigators also found that shortened telomere length was directly
related to evoked pain sensitivity and altered brain structure,
suggesting that pain may accelerate cellular aging. 'Telomeres are
protein complexes that cap and protect the ends of chromosomes,' said
Afton L. Hassett, PsyD, associate research scientist in the Chronic
Pain & Fatigue Research Center at the Ann Arbor institution.
'Critically short telomeres put cells at risk for apoptosis and death.
This is the first study to show that telomere length is associated
with clinical pain
alone, as well as experimental pain. I will also
caution, however, that this was a highly exploratory study.'


Feeling One's Biological Age

Telomere length has been associated with a variety of age-related
illnesses, including cardiovascular disease, osteoarthritis,
osteoporosis and several forms of cancer. Sex, race, socioeconomic
status and even level of education appear to affect the length of a
person's telomeres, as do behaviors and physical characteristics such
as smoking, body mass index, stress and depression.

That suggests telomere length is a measure of biological as opposed to
chronological age, Dr. Hassett said.

To determine the relationship, if any, between telomere length and
pain, the researchers evaluated leukocyte telomere length in 66 women
with fibromyalgia and 22 healthy female controls. All volunteers
completed questionnaires including the Brief Pain Inventory (BPI; 0-10
scale) and the Center for Epidemiologic Studies Depression Scale
(CESD). Twelve of the women with fibromyalgia underwent quantitative
sensory testing and neuroimaging.

After controlling for age, pain was found to be associated with
shorter telomere length (rpartial = -0.267; P=0.039), according to Dr.
Hassett, who reported the findings at the 2012 annual meeting of the
American Society of Anesthesiologists (abstract 012).

Patients were categorized as experiencing high levels of pain (BPI
??5; n=30) or lower levels of pain (BPI<5; n=31). Women who scored at
least a 5 on the BPI-the cutoff for 'high' levels of pain-were more
likely to have shorter telomeres regardless of their chronological age
(F=5.39; P=0.024). 'This difference,' Dr. Hassett said, 'represents
approximately five years of aging.'
That estimate is based on a
previous study that linked the deterioration of telomeres to time
(Proc Natl Acad Sci USA 1998;95:5607-5610).

The researchers found no association between scores on the CESD and
telomere length. 'We also wondered whether combining age and
depression might have an additive effect,' Dr. Hassett continued.
After adjusting for age, patients categorized as high pain/high
depression had telomeres that were 265 base pairs shorter, on average,
than those with low pain/low depression (P=0.043), a difference
consistent with approximately six years of chronological aging.

In quantitative sensory testing, the researchers found a 'very high
correlation' between telomere length and sensitivity to pain that was
statistically significant. 'People with the shortest telomere lengths
were by far the most sensitive to pain,' Dr. Hassett said.

Neuroimaging in a subset of 12 patients found that telomere length
also was related to a person's volume of gray matter. 'We found that
the fibromyalgia patients with shorter telomeres showed less brain
matter volume in pain processing areas of the brain,' Dr. Hassett said.


Background inflammation a possible explanation

Exactly why telomere length has such a significant association with
these variables is open to interpretation, although Dr. Hassett
offered a possible explanation. 'The predominant theory is that
decreases in cortisol levels may create an environment where there's
greater low-level inflammatory activity,'
she said. 'Ultimately, we
would really like to verify these results in a larger study and even
consider chronic pain patients with other diagnoses.'

W. Michael Hooten, MD, associate professor of anesthesiology at Mayo
Clinic in Rochester, Minn., called the study fascinating. 'This is a
unique avenue of investigation that could broaden the understanding of
the molecular mechanisms of chronic pain,' Dr. Hooten said. 'It's a
relatively small sample, and it'll be interesting to see how this
plays out in a larger group of patients, to see if the findings can be
replicated.

'It would also be interesting to determine if treatment of the
underlying pain condition can halt or retard telomere shortening,' Dr.
Hooten continued. 'This could have important clinical implications.
For example, if an association exists between treatment response and
telomere length, this could help identify and measure the
effectiveness of various interventions for fibromyalgia.'

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(c) 2013 McMahon Publishing

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