GENE MIGHT AFFECT VULNERABILITY TO NICOTINE

SCIENTISTS have identified another gene that might affect how
vulnerable a person is to cigarette addiction. The finding may help
researchers develop new ways to stop smoking.

Having a certain form of the gene makes it easier to kick the habit,
or perhaps to avoid getting hooked in the first place, two studies
suggest. But that apparent influence is modest.

``This is just one small piece of the puzzle'' of what influences
smoking behavior, said psychologist Caryn Lerman, an author of one of
the studies.

Lerman is director of cancer genetics at the Lombardi Cancer Center of
Georgetown University Medical Center in Washington. Her work and a
follow-up study by Dean Hamer of the National Cancer Institute and
colleagues appear in this month's issue of the journal Health Psychology.

It's at least the third gene to show evidence of an effect on smoking.
Scientists hope that by understanding such biological influences, they
can tailor treatments to particular smokers and get hints for finding
better therapies.

Ernest P. Noble, a psychiatry professor at the University of
California-Los Angeles, who studies the genetics of smoking, said the
evidence that the gene influences smoking isn't very strong, though he
added: I believe it is a real effect.''

But Ken Kidd, a Yale University geneticist who has studied the genetic
marker used by the researchers, criticized the design of the studies
and analysis of the results. ``I do not accept their conclusions,'' he
said.

Nicotine causes a surge of a substance called dopamine between certain
brain cells. That feels good to the brain, so it encourages addiction.
Brain cells use squirts of dopamine to communicate, and the gene in
the new research tells brain cells how to make a structure called a
transporter that mops the chemical up.

Why would one version of this gene discourage nicotine
addiction?

Lerman and colleagues theorize that it leads to a less efficient
dopamine transporter, which leaves more dopamine between the brain
cells. That might reduce a person's desire to pump up dopamine levels
by using nicotine, they suggest.

Hamer's team found that people with the apparently protective version
of the gene scored lower than other people on novelty-seeking, a
personality trait that includes impulsiveness and an interest in
experiencing new sensations.