Vanity Fair reports:

Among scientists, it’s not a popular term these days, probably because “mass hysteria” summons the image of a huge mob, panicked into a stampede (with a whiff of misogyny thrown in). But properly understood, the official definition, when applied to the events [at the American Embassy] in Havana, sounds eerily familiar. Conversion disorder, according to the International Journal of Social Psychiatry, is the “rapid spread of illness signs and symptoms among members of a cohesive social group, for which there is no corresponding organic origin.”

We tend to think of stress as something that afflicts an individual who is enduring heavy psychological pain. But conversion disorder, or mass psychogenic illness, as it is also known, is essentially stress that strikes a close-knit group, like an embassy under siege, and behaves epidemiologically—that is, it spreads like an infection. Because the origins of this affliction are psychological, it’s easy for those on the outside to dismiss it as being “all in the victim’s mind.” But the physical symptoms created by the mind are far from imaginary or faked. They are every bit as real, every bit as painful, and every bit as testable, as those that would be inflicted by, say, a sonic ray gun.

“Think of mass psychogenic illness as the placebo effect in reverse,” says Robert Bartholomew, a professor of medical sociology and one of the leading experts on conversion disorder. “You can often make yourself feel better by taking a sugar pill. You can also make yourself feel sick if you think you are becoming sick. Mass psychogenic illness involves the nervous system, and can mimic a variety of illnesses.”

Scientists in Cuba were among the first to realize that the outbreak at the American Embassy conformed to mass hysteria. Mitchell Valdés-Sosa, director of the Cuban Neuroscience Center, told The Washington Post, “If your government comes and tells you, ‘You’re under attack. We have to rapidly get you out of there,’ and some people start feeling sick … there’s a possibility of psychological contagion.”

Some American experts who were able to review the early evidence concurred. “It could certainly all be psychogenic,” Stanley Fahn, a neurologist at Columbia University, told Science magazine.

If you retrace the key events and anomalies of the outbreak at the embassy in Havana, every step of the way corresponds to those in classic cases of conversion disorder. [Continue reading…]