Perhaps, but I wondered whether in these cases, it might be nothing more profound than a quirk in the neurobiology of sex that made these patients feel awful.

Image Credit... David Suter

Little is known about what happens in the brain during sex. In 2005, Dr. Gert Holstege at the University of Groningen in the Netherlands used positron emission tomography to scan the brains of men and women during orgasms. He discovered, among other changes, a sharp decrease in activity in the amygdala, the brain region involved in processing fearful stimuli. Aside from causing pleasure, sex clearly lowers fear and anxiety.

The anthropologist Helen E. Fisher, of Rutgers, used functional magnetic resonance imaging to look more broadly at the neural circuitry of romantic love. She showed a group of young men and women who reported being passionately in love a photo of their beloved or a neutral person. Subjects showed marked activation in the brain’s dopamine reward circuit only in response to the beloved, similar to the brain’s response to other rewards like money and food.

Could it be that some patients have particularly strong rebound activity in the amygdala after orgasm that makes them feel bad?

The research literature is virtually silent on sex-induced depression, but a Google search revealed several Web sites and chat rooms for something called postcoital blues. Who knew? There, I read many accounts nearly identical to those of my patients, with reports of various remedies for the malady.

When physicians run through the usual treatments to no avail or find themselves, as I did, in uncharted territory with little evidence as to what to do, they can consider so-called novel treatments. Often, you design such a treatment based on your speculation about the underlying biology of the syndrome at hand. This can involve using approved drugs in situations for which they are hardly ever prescribed.