Folie à deux: the madness of two

September 10, 2020

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Folie à deux is a striking phenomenon, but poorly understood. It seems to me that its striking nature distracts us from something that's far more common, and far easier to understand.


Folie à deux, or the 'madness of two', is typically characterised as a case in which someone has such powerful delusions, or is has such an influential character, that they influence another to take on the delusion as their own. This feature of transmission was once a part of the name.

Initially described as folie communiqué (communicated madness) in 1860 by neurologist before his time, Jules Baillarger, after a couple so caught up in each others' delusions physicians were unable to tell who became psychotic first, it eventually became known as folie à deux in 1877 through the work of Charles Lasegue and Jean-Pierre Farlet, doctors of some renown at the time.

Typically, a dominant person in a relationship will develop (or already be experiencing) some kind of delusion(s). Subsequently, the other person(s) in the relationship will begin to experience the same delusions. Or perhaps instead they will merely come to believe the other person's delusions. This shared madness can also be less unidirectional. Rather than folie imposée, we might see folie simultanée, in which both parties may already be delusory individually, but as they interact, their delusions coalesce.

Nor does folie have to occur in pairs. It can involve more than two people, for instance folie à trois or folie à famille, or the less French and more expansive 'shared psychotic disorder'. Regardless, these all boil down to one key concept. The delusion(s) of one is matched by another.

Precise information on how common the phenomenon is hasn't really surfaced yet. But we've seen cases in places as far flung as Saharan Africa, in India, and a couple of Swedish tourists visiting the UK, all of which share the core features of the phenomenon. This indicates that it might not be necessarily frequent, but the experience has a universal quality to it.

And there, as the Bard would say, lies the rub. Folie à deux is a tough case to identify for health professionals. In fact, there are fairly stringent requirements to conclusively diagnose a case. There needs to be a commonality of delusion (of course), intimacy in the relationship, and acceptance or support of each others' delusions. The details of these features aren't always apparent to an outsider. Nor are closely coupled people often willing to share the intimicies of their connection to another.

However, there is a common thread; intimacy in the context of social isolation. Folie à deux is perhaps the most intriguing example of the crucial nature of our need to be social. It exemplifies, in its own puzzling way, the lengths the mind will go to to feel connected to something bigger. It's also emblematic of the myriad peculiarities of love.

There is always some madness in love.

Nietzche, Thus Spake Zarathustra

Which raises an interesting question

There are interesting features present in the literature on folie à quel que soit. The first is that this is often a dyadic affair. This makes sense, because any kind of influence is more potent when focused. But this dyadic nature is not always the case. A spectacular case of folie a famille occured in Australia recently. In this case, the family fled their farm for hundreds of kilometres in apparent terror of some following threat. Some family members escaped the chaotic week-long journey unaffected, but others seemed to be in various altered states. This episode was preceded by no apparent drug use or history of mental illness. And the members of the family reporting afterwards seem as puzzled by the episode as anyone. For example:

It's very confusing, I still feel confused

Or from another:

You do start thinking the same way... you can get sick in some way

Even more recent were the Burari family deaths in India. Eleven members of a family dead by apparent suicide, their faces swathed in tape and cotton and cloth. Indeed many suspected cases of shared folie regard people who died doing something baffling. These may not be cases of shared delusion, but the number of suspected cases does not line up well with the number of reported cases.

In larger numbers, this makes one wonder how many of these members shared the delusion, and how many simply went along (or were forced along) for the ride? In the case of the Australian family, one member, Mitchell, explicitly reported that he did not share his family's fear. He simply "couldn't leave them". This kind of half-hearted participation would surely make it hard to diagnose a shared madness. Given the stringent criteria for diagnoses, one wonders how many examples simply escape our notice, particularly outside of the more focused dyadic cases.

The second feature to consider is that many, many cases of shared madness involve violence. Murder, suicide, and injury. We might even say that these cases are overrepresented. Psychoses run the full gamut of bizarre perceptions and beliefs, not simply those that end in pain. So why is shared psychosis so much more harmful?

The answer may be that perhaps it's not.

Theranos was a multibillion dollar biotech startup headed by the now infamous Elizabeth Holmes. The company raised huge sums with claims of a revolutionary blood test. The bizarre antics of Elizabeth Holmes and her boyfriend/business partner Balwani have become jokes, after the downfall of the company. A pretend wolf permitted to roam the sterile halls of the company, freely shitting anywhere it likes. Holmes speaking in different voices. Rampant paranoia.

On page 143 in the book Bad Blood, the author reports suggestions that this may have been a case of folie à deux. The couple, Holmes and Balwani, may have been living some elaborate shared delusion. A delusion that sucked in thousands who, like Mitchell from the Australian family earlier, were not necessarily sharing the delusion but simply "couldn't leave" for one reason or another.

Which leads me to another question: how many cases of folie are missed, simply because they aren't spectacular enough? Or put another, more interesting way, are the more spectacular nature of the reported cases distracting us from something more fundamental?

I said before that the common thread in cases of shared madness is intimacy in the context of social isolation. Social isolation is a unexpectedly dangerous thing for humans. I've said it before, but loneliness is emerging as one of the single greatest threats to human health, both mentally and physically. When we combine isolation with new intimacies, perhaps it shouldn't surprise us that things can start to look a little strange. Given the widespread nature of social isolation, I think we can be sure that the faces of shared madness are more varied, and more subtle, than we can imagine.

This article forms part of a series on successful prophets.

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