Why does falling in love turn seemingly rational, even-keeled, considerate people into deranged, raving, volatile, self-centered psychos in dire need of an exorcism, especially teenagers?

Welcome to Cupid’s laboratory. There is indeed a biochemistry of love. Helen Fisher, an anthropology professor at Rutgers University-along with two colleagues, Arthur Aron and Lucy Brown-used an MRI machine to study the brains of peoples who describe them selves as being wildly “in love.” When each subject gazed at a photograph of his or her sweetheart, the ventral tegmental area and the caudate nucleus lit up. The caudate nucleus is the site of a dense network of receptors for the neurotransmitter dopamine. Donatella Marazziti, a psychiatry professor at the University of Pisa in Italy, measured the serotonin levels of the neurotransmitter serotonin in the blood of people who’s been in love for several months and who pine or are otherwise preoccupied whit their lovers for at least four hours a day. She found that the serotonin levels in the love-struck subjects were as low as the serotonin levels in people with obsessive-compulsive disorder (OCD).

So if you’re feeling “madly” in love, or a little “insane in the membrane,” or “crazy, crazy for feeling so lonely,” there’s a solid, scientific basis for losing your heart AND your marbles.