Without diminishing the extent of her suffering, her research or her writing, I am tempted to say that in a sense it reads too well. A story of madness as told by the sane can never be complete. (Which is one reason I love Dostoyevsky's The Double, by the way.)
In his essay “What is Postmodernism?”, Jean-Francois Lyotard wrings his hands over of those “postavantgardists” who pursue reality—by which he means unity, simplicity and communicability—to the exclusion of the “sublime”, or that we can only conceive of but never present. The paradigm of this realism, he says, is to be found in photography and film, which “stabilize the referent, … arrange it according to a point of view which endows it with a recognizable meaning, … reproduce the syntax and vocabulary which enable the addressee to decipher images and sequences quickly and so to arrive easily at the consciousness of his own identity as well as the approval which he thereby receives from others”. Cultural artifacts, in order to answer to the demands of academia and the free market must be so made that "the public will recognize what they are about, while understand what is signified, will be able to give or refuse its approval knowingly, and if possible, even to derive from such work a certain amount of comfort.”
This in mind, we might regard Cahalan’s work, for all its merits, as the collusion of the healthy. Like Bilbo's There and Back Again, with emphasis on the last three words. She weaves a coherent image of that which could never cohere—whole weeks pass as a patchwork of delusions and otherwise lost memories. What has been distorted or lost has been corrected, filled in and harmonized by the witness of those who had been with her. Cahalan as a unified subject re-emerges on the other side of her illness intact.
Nor has her belief in the unified subject been significantly shaken. We might say: given the choice between breaking out of her language game or reinforcing it, she has chosen the latter. She might, for example, have returned to the intense conviction of her previous delusions to wonder how much of sanity is conventional, or ask why she had the specific hallucinations she did (as physical sciences only point to why an injury might cause hallucination in general), or wondered whether abnormalities in the physical substrate might be revelatory, allowing her access to rare but real psychic possibilities. Yet more fruitfully, she might wonder what it says about us that our sense of conviction can be so misaligned with what is manifestly the case.
What's more, in liberally dropping in sidebar tutorials on “catatonia”, the “amygdala” and the effects of a damaged “hippocampus” on memory, she calls on the authority of science as her witness. Neurology and psychology, as she tells us, converge to a unified, and correct, account of the human mind. And from this we are to derive, as Lyotard says, a certain amount of comfort: the statistically normal, the aesthetically normal and the ethically normal converge, and this is a fact of science.
But the worst is yet to come. It happens when the entire floor drops out from under you, when you realize that whomever it is you are usually talking to has a normally distributed histogram—but that this histogram doesn’t appear to have any particular reason to commend it aside from its survival value. This histogram, just like yours, is but the projection of those who, for whatever reason, already started out with that histogram. The grounds of sanity are remarkably elusive. And so anyone's attempts to untie your knots start to feel like an invasion, and imposition, a desire to submerge that tiny spit of land you call your own in with a water that’s too cold to bear. Obsession becomes paranoia, but at least obsession and paranoia are home.
Its first manifestation might be something like this. You twitch a finger, you roll an eye, some minor gesture as you lay trying to fall asleep. But you can't simply do that! On what authority, to what end? What's more: in doing that, you have, without the slightest consideration, excluded the doing of countless other things that might have been done in its stead, and so now the manifold branching of the future has been casually but unalterably determined, and in ways you'll never know. (Descartes, friends, was a rank amateur of doubt!) And so you must...undo it! But how? By rolling your eye in the opposite direction, to cancel it out. Now in a sense these two actions, as opposites, resolve to no action. But in another sense, taken together they form a single action, a single do-undo, which as such must be subjected to the same logic of the original assertion: it must be undone. But how? By running it in reverse: undo-do. But then this must be reversed, and so on. The result is an exponential expansion, which in the language of binary mathematics (1 for do, 0 for undo) looks something like this:
0110 1001 1001 0110
0110 1001 1001 0110 1001 0110 0110 1001
Another couple of iterations and it becomes totally intractable. You simply lose your place. But, lo!, another action is asserted, and now at least it can be subjected to the same restorative treatment. Palindrome, palin-palindrome, palin-palin-palindrome...but palindromes with real content. Semantic palindromes? Pragmatic palindromes?
Ontological palindromes? The helmsman of the universe? Was Plato's demiurge obsessive compulsive?
And it all gets worse through isolation, which is inevitable given that a 9 year old is hardly equipped to put it into words - that would take the formal study of something mathematical and ideally a cursory acquaintance with Hegel's Logic. And even then, who could possibly understand if you were to say it? Or does everyone do this? Obviously not, because otherwise they'd be stuck in similar cycles of the physio-cognitive paralysis that ensue when this frame of mind is brought to the social realm.
An utterly astonishing thing happens when you find the right serotonin reuptake inhibitor. Your histogram suddenly snaps back to normal, leaving you to wonder what had happened. That obsession had been so logical—in fact it was rare achievement of logic. But where is it now? It’s still there grumbling, threatening to punch you again, but it can’t as long as your seratonin is flowing right. You can take yourself through all the arguments that used to hold you in thrall, but they simply don’t seem compelling any more.
That something so manifestly mental could so directly rest on the physical—it's enough to cure anybody of belief in mind-body dualism. But as we ponder it we can’t help but wondering whether the earth orbits the sun or vice-versa, or whether there is a reference frame from which we could ever sort it out. The language-games that saturate society saturate the self as well.