DOPAMINE NOT SECRET TO ADDICTION, STUDY SAYS

Dopamine may not be the brain's "feel-good" chemical after all, a
study found, suggesting that scientists trying to unlock the secrets
of drug addiction may have been off target for the past two decades.

The naturally produced brain chemical, rather than being the key
player in the pleasure process, is only a messenger and one of several
factors, according to the study, published Thursday in the journal
Nature.

"It certainly says the picture is much more complicated than being
just dopamine alone, and it will lead to the search for other chemical
substances in the brain," said the study's author, chemist R. Mark
Wightman of the University of North Carolina-Chapel Hill.

Dopamine, discovered in 1957, came into prominence in the early 1960s
when scientists discovered that several antipsychotic drugs targeted
it. In the late 1970s, researchers found that cocaine, heroin and
other addictive drugs increase levels of dopamine in the body.

Since then, some scientists have tried to develop a medication that
would cure cocaine addiction by blocking dopamine.

The latest study is another in a series that cast doubt on that
approach.

Dopamine appears to be related to "novelty, predictability or some
other aspect of the reward process, rather than to hedonism itself,"
the researchers reported.

What chemical or process is ultimately responsible for the pleasure is
"not really clear right now."