Are antidepressants taking the edge off love?

LOVE'S first rush is a private madness between two people, all-consuming and, if mutually felt, endlessly wonderful.

Couples think about the other obsessively -- on a roller coaster of euphoria when together, longing when apart.

"It's temporary insanity," says Helen Fisher, an evolutionary anthropologist at Rutgers University.

Now, from her studies of the brains of lovers in the throes of the initial tumble, Fisher has developed a controversial theory. She and her collaborator, psychiatrist J. Anderson Thomson of the University of Virginia, believe that Prozac, Zoloft, Paxil and other antidepressants alter brain chemistry so as to blunt the intense cutting edge of new love.

Fisher and Thomson, who describe their theory in a chapter in the book, "Evolutionary Cognitive Neuroscience," aren't talking just about the notorious ability of the drugs to damp sexual desire and performance, although that, they believe, plays its part. They think the drugs also sap the craving for a mate -- perhaps even the brain's very ability to fall in love.

And that would be bad news, given the widespread use of antidepressants in this country -- about 10% of adult women and 4% of adult men take the drugs, according to a 2004 report by Centers for Disease Control and Prevention's National Center for Health Statistics.

Though they still lack solid evidence that more Americans are having trouble falling in love these days, the scientists do have animal and laboratory science along with some human studies to whet their research appetites.

For one thing, there's brain chemistry. The chemicals involved in the heart-pounding fall over the cliff into another's life, including dopamine, norepinephrine and serotonin, are the very chemicals altered by many anti-depressants.

Fisher cites animal studies showing, for example, that female prairie voles, naturally loyal to one mate, lose interest in him when dopamine is suppressed. The early human version of mate-pairing -- romantic love -- is also associated with increased activity in dopamine pathways. And SSRI antidepressants suppress that activity.

SSRIs are also known to curb obsessive thinking, the kind of focused state that is central to the first blush of romance.

For both these reasons, Fisher suggests that SSRIs could jeopardize intense romantic love.