She and her colleagues measured serotonin levels in the blood of 24 subjects who had fallen in love within the past six months and obsessed about this love object for at least four hours every day. Serotonin is, perhaps, our star neurotransmitter, altered by our star psychiatric medications: Prozac and Zoloft and Paxil, among others. Researchers have long hypothesized that people with obsessive-compulsive disorder (OCD) have a serotonin "imbalance." Drugs like Prozac seem to alleviate OCD by increasing the amount of this neurotransmitter available at the juncture between neurons.
Marazziti compared the lovers' serotonin levels with those of a group of people suffering from OCD and another group who were free from both passion and mental illness. Levels of serotonin in both the obsessives' blood and the lovers' blood were 40 percent lower than those in her normal subjects. Translation: Love and obsessive-compulsive disorder could have a similar chemical profile. Translation: Love and mental illness may be difficult to tell apart. Translation: Don't be a fool. Stay away.
Of course that's a mandate none of us can follow. We do fall in love, sometimes over and over again, subjecting ourselves, each time, to a very sick state of mind. There is hope, however, for those caught in the grip of runaway passion—Prozac. There's nothing like that bicolored bullet for damping down the sex drive and making you feel "blah" about the buffet. Helen Fisher believes that the ingestion of drugs like Prozac jeopardizes one's ability to fall in love—and stay in love. By dulling the keen edge of love and its associated libido, relationships go stale. Says Fisher, "I know of one couple on the edge of divorce. The wife was on an antidepressant. Then she went off it, started having orgasms once more, felt the renewal of sexual attraction for her husband, and they're now in love all over again."
Psychoanalysts have concocted countless theories about why we fall in love with whom we do. Freud would have said your choice is influenced by the unrequited wish to bed your mother, if you're a boy, or your father, if you're a girl. Jung believed that passion is driven by some kind of collective unconscious. Today psychiatrists such as Thomas Lewis from the University of California at San Francisco's School of Medicine hypothesize that romantic love is rooted in our earliest infantile experiences with intimacy, how we felt at the breast, our mother's face, these things of pure unconflicted comfort that get engraved in our brain and that we ceaselessly try to recapture as adults. According to this theory we love whom we love not so much because of the future we hope to build but because of the past we hope to reclaim. Love is reactive, not proactive, it arches us backward, which may be why a certain person just "feels right." Or "feels familiar." He or she is familiar. He or she has a certain look or smell or sound or touch that activates buried memories.
When I first met my husband, I believed this psychological theory was more or less correct. My husband has red hair and a soft voice. A chemist, he is whimsical and odd. One day before we married he dunked a rose in liquid nitrogen so it froze, whereupon he flung it against the wall, spectacularly shattering it. That's when I fell in love with him. My father, too, has red hair, a soft voice, and many eccentricities. He was prone to bursting into song, prompted by something we never saw.