A survey of nearly 13,000 Britons found that smokers complain more often of discomforting or disabling musculoskeletal pain than never-smokers.

The association was found "even in ex-smokers," suggesting that smoking may cause long-term damage to muscle tissues or changes in the neurological pain response, according to researchers led by Dr. K. T. Palmer of Southampton General Hospital in Southampton, UK.

Writing in the January issue of Annals of Rheumatic Diseases, the UK team notes that previous studies have suggested links between smoking and pain, especially chronic back pain. However, most of these studies did not factor out lifestyle factors, such as on-the-job manual labor, as a possible contributing cause.

In their study, Palmer's team had 12,907 adults fill out detailed questionnaires that covered topics such as smoking history, work activities and levels of sporadic or chronic musculoskeletal pain.

They found that, compared with those who had never smoked, current smokers had about a 50% higher incidence of reporting "pain in the past year preventing activity," meaning pain so severe it precluded the individual from going to work or performing housework or hobby activities. Pain at all sites--lower back, shoulders, elbows, hands, neck and knees--was higher in smokers than never-smokers. What's more, this association held even among respondents who had white-collar or other jobs that did not require heavy lifting or moving.

Why might smoking raise pain levels? Studies have suggested numerous explanations. First, nicotine is a powerful stimulant that "could affect the manner in which the brain processes sensory stimuli and the central perception of pain," the researchers say--effectively cranking up the smoker's pain response.

Secondly, "tobacco smoking might cause general damage to musculoskeletal tissues" by reducing blood supply to these tissues, raising clotting risks, or reducing the flow of nutrients to muscles and joints.

On the other hand, those who choose to take up smoking might be psychologically predisposed to simply feel and report pain at lower thresholds than non-smokers, the researchers say. They point to previous studies that suggest that smokers react more quickly to painful stimuli than nonsmokers.

Whatever the reason, the fact that even ex-smokers reported discomfort more frequently than never-smokers leads researchers to conclude that the pain-related effects of smoking can last for years, due to "tissue damage or a prolonged resetting of the threshold for pain."

(Agencies via Xinhua January 6, 2003)