Science notes: Efficacy of tobacco taxes is tied to gene variation

Tobacco use has declined sharply since the 1960s, but for the past 20 years about 20 percent of the population has continued to smoke -- despite the imposition of steep tobacco taxes in many states.

Now an economist has published an unusual study in December's PLoS One that suggests a reason: About half the population has a variation in a specific gene connected to nicotine addiction that makes them more likely to respond to cigarette tax increases.

Jason Fletcher, an associate professor of health policy at Yale, used data on 6,178 adults in a large national health survey that gathered information on smoking habits and also collected biological specimens for genotyping. About half of the subjects had a variation in a gene for a nicotine receptor in the brain that is thought to control the pleasure reward of nicotine consumption. Fletcher tracked the statistical relationship between taxation, smoking and this gene.

He found that a 100 percent increase in taxes had a significant effect only on people with this particular genetic variation in DNA sequence. The other half of the population was immune to the effect of taxation.

Fletcher urged caution in interpreting his findings since this is the first study of its kind. Still, he said, "As we get more and more convinced that people with certain genotypes may respond differently to policies, that means that alternative policies may be necessary."

NEW YORK TIMES

Signs of the cancer-causing human papilloma virus in women near or at menopause may be a reawakened dormant infection.

The data raises a new concern for women now entering menopause, suggesting a significantly higher risk for HPV infections than those of the previous generation, researchers said. The findings may mean that women need to continue routine screening after age 40, said Patti Gravitt, one of the study authors.

BLOOMBERG NEWS

In a finding that points to a link between environmental pollutants and autism, a study shows that children who were exposed to the highest levels of traffic-related air pollution during gestation and in early infancy were three times more likely to be diagnosed with the disorder than were those whose early exposure to such pollutants was very low.

The study in the Archives of General Psychiatry found that early exposure to high levels of air pollution in general was linked to an increased likelihood of autism in a group of more than 500 children followed for several years from birth. Their findings suggest that the link between air pollution and autism is evident largely at the highest levels of exposure, and slightly higher when the exposure comes later in a woman's pregnancy. The strongest link was found between exposure to nitrogen dioxide-a pollutant found plentifully around freeways-and autism, while exposure to particulates was less strongly linked to autism.

While they cautioned that the link is not proof that pollution causes autism, they suggested how pollutants could influence brain development. Diesel exhaust particles and polycyclic aromatic hydrocarbons have been shown to interfere with gene expression in healthy brain development. Other research suggests that traffic-related air pollutants induce oxidative stress in the brain and body.