FRIDAY, March 2 (HealthDay News) -- Smokers are at higher risk
of developing the autoimmune skin condition psoriasis than
nonsmokers, a new study finds, possibly because smoking pushes the
body's immune system into overdrive, one expert suggests.
The research doesn't directly prove that smoking causes
psoriasis, and the wide majority of smokers would avoid developing
the condition even if they faced an increased risk.
Still, the findings provide yet another reason for smokers to
drop the habit, said study co-author Dr. Abrar Qureshi, an
assistant professor of dermatology at Harvard Medical School. "It
behooves us even more to advise individuals who are smoking to
quit," he said, especially because psoriasis itself is linked to
higher risks of diabetes and heart attacks.
Psoriasis, which tends to occur in adulthood, causes itchy and
painful patches of thick, scaly and reddened or whitened skin. The
patches often appear on the knees and elbows.
The condition appears when the immune system mistakenly attacks
skin cells. Treatments are available, but they may not keep
psoriasis at bay forever.
Dermatologists have wondered whether smoking makes psoriasis
worse, Qureshi said. In the new study, investigators examined
research projects that followed more than 185,000 medical
professionals in the United States for as long as two decades. They
looked specifically at 2,410 people who'd been diagnosed with
After adjusting their statistics so they wouldn't be thrown off
by high or low numbers of people who were overweight or had other
risk factors for psoriasis, the researchers found that current
smokers were about 1.9 times more likely to have psoriasis than
nonsmokers. Past smokers were nearly 1.4 times more likely to have
The study found a "graded reduction of risk" as time passed
after a participant had quit smoking.
The study didn't calculate the actual percentages of smokers,
nonsmokers and past smokers who developed psoriasis. However,
Qureshi said about 2 percent to 3 percent of the general population
has the condition.
It's possible that something other than smoking boosts the risk
of psoriasis in smokers, Qureshi said. It would be unethical to
confirm that smoking is the cause because that would require
researchers to randomly assign some people to smoke, he said.
Even if researchers could confirm that smoking causes or worsens
the condition, the question would remain how it might do so.
Qureshi said that while it's possible that simply being around
smoke could hurt the skin externally, "there are a number of
autoimmune conditions that are exacerbated and caused by inhaled
Dr. Joel Gelfand, medical director of the University of
Pennsylvania's department of dermatology clinical studies unit,
said that "since psoriasis is an inflammatory disease, it is
plausible that smoking lights the fire that leads to chronic
inflammation of psoriasis in people who are susceptible."
Gelfand, who's familiar with the study results, said the
research confirms previous findings.
"Importantly, the investigators showed that the risk of psoriasis increased with the amount of smoking and a reduction in risk of psoriasis was observed with an increase in time from when people quit smoking," he said. "Smoking is common among patients with psoriasis and extremely common among patients with a variant of psoriasis called 'palmar-plantar pustular psoriasis,' which can be severely disabling."
Smoking has already been associated with aging and wrinkling of
the skin, Gelfand said. Psoriasis, he added, "is another reason to
The study appears in a recent issue of the
American Journal of Epidemiology.
For more about
psoriasis, visit the U.S. National Library of Medicine.
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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