Great article. The strangest part for me was the sudden onset that people experienced. When I think of psychological disorders, I think of how symptoms usually start small and gradually get more severe.
Everybody gets small phantom itches from time to time. I think the idea of an "itch nerve malfunction" makes the most sense. One could imagine some sort of infinite loop of itch nerves triggering each other, exacerbated by constant scratching.
Any strange psychological behavior, such as extreme cleanliness, or being convinced that ordinary clothing fibers are the cause, would be an obvious natural response if you couldn't figure out why you were suddenly so itchy.
Also, anyone who has to deal with contact lenses knows that our hands and fingers always have tiny little fibers stuck to them.
I was diagnosed with Chronic Idiopathic Urticaria a little while back. It's a histamine imbalance. It sounds similar to the article in that over a couple of days I spontaneously broke out in incredibly itchy hives. The itching was incessant and lasted for months. Even with a diagnosis I found myself getting frustrated and despondent with living with it day to day. Thankfully medicine has answers for me; via constant doctors appointments and $1,000-per-session shots that mask the symptoms.
A couple years ago, I realized that I was constantly itchy and rash-y. My family has a history of allergies and mild skin conditions (my Dad calls it the "crud"). After some time, I figured out that it must be dermatographism—an allergy to skin pressure, essentially. Since then I've taken a Zyrtec a day and alleviates the itchiness from the chronically-unable-to-concentrate-craze-inducing level to the acute and mildly annoying. I should probably explore a real diagnosis and treatment at some point, but I very much sympathize with anyone plagued by ceaseless itching. It's pretty horrible.
FWIW, I can share my anecdotal periodic itching story:
Somewhat infrequently (a few times every year, for the past 11 years) I will go into a "mode" where showering/bathing of any kind will invariably be followed by itching afterwards. This lasts anywhere from a few days (no scratching) to a couple of weeks (some scratching). The itch is concentrated on my front body and legs (never face/arms, rarely back). Nothing helps much except not scratching while it runs its course.
What I've found interesting is that this doesn't manifest during particular stress / downs / whatever. It can be during an awesome holiday in the summer, or over Christmas, or an ordinary work week. But the itching comes after every shower, as if my body picks up some irritant from the water that doesn't affect my hands/face at all. It also isn't "something in the water where I live", as this has manifested in various parts of the UK and Greece.
On a scale of 0 to 10, I'm at 2 as to how manic I've gone about this: when it manifests, I'll start using hypo-allergenic shower stuff, paste myself with moisturising cream and just wait it out. Dermatologists have been the expected/reputed amount of helpful: "sounds like you're sensitive to something in the water", so they gave me a stronger cream, which also didn't reduce the itching. What worked most was not picking/scratching, or at least not enough to break skin/cause small wounds, etc. Depending on your "itch tolerance"[1] takes a little bit of mental focus, so I wouldn't, say, shower before going to bed, but showering and going out was easy.[2] Then, a few days later, I shower -> all good.
I guess my point is, while mine could also be somewhat psychologically induced, I don't think this is the case. Something seems to trigger an "itch flare" which (a) isn't linked to my mood or stress levels, (b) always goes away if I can "forcefully" ignore the urge to scratch and (c) is somehow water related, but not to a particular water source. I feel like If I gave in to the scratching urges, it would be a whole different kind of rabbit hole. So my issue doesn't really compare in the least with what these folks are going through - just a periodic experience of a similar thing at a lower intensity level. You can't always "push aside" pain, so it stands to reason that you can't always "push aside" the scratching urge, and that's when it takes up a life of its own. I am very grateful for not having to deal with this full-time. Not scratching while itching can be proper work, depending on the intensity/duration of the itching spell(s).
As for what mine is, I have no clue, and as long as we stay on our current terms, I'm somewhat content with that. Allergies and sensitivities can be pretty hard to pin down.
PS: Another reason I don't think my itching is psychological - I just read the article, then wrote this, and I'm not itching - yet ;)
[1] if "pain tolerance" is a thing, and itching has its own receptors and all, ...
[2] Except once in a while, in public/with friends/with people anyhow, the itch will "win" and I'll forget that I shouldn't do my instead-of-itching-last-measure, which is to hit/punch the itching spot rather than scratch (my hand is already moving of its own accord, so something needs to happen). Not a masochist in the least, but rather I've noticed that the little physical pain takes away the edge of the itching. YMMV, not offering this as advice. However, you do, you may want to avoid doing that in public, or at least don't follow up any questions with a grunt like "it was that or flaying myself with this steak knife", or you may stop being invited to dinner parties.
FWIW, I also have experienced a similar itch. Most of the symptoms also sound very similar (never on the face etc). Haven't had one of those for a few months, so I am not able to recollect more details about this though.
I too finally settled on trying to ignore the itch as much as possible. It lasted for only like half an hour after the showers, so I was not motivated enough to dive deep to figure out the root cause. Possible causes may include - Chemical composition of the water you use, Soap/Shampoo etc.
It was suggested to me that the borewell water that we use may be the culprit, but since we have multiple sources of water at home (well / borewell / public supply) and since I did not bother going more in depth to figure this out, no clues on this front yet. Also, I have had the same problem at least a few times in another city as well.
Everybody gets small phantom itches from time to time. I think the idea of an "itch nerve malfunction" makes the most sense. One could imagine some sort of infinite loop of itch nerves triggering each other, exacerbated by constant scratching.
Any strange psychological behavior, such as extreme cleanliness, or being convinced that ordinary clothing fibers are the cause, would be an obvious natural response if you couldn't figure out why you were suddenly so itchy.
Also, anyone who has to deal with contact lenses knows that our hands and fingers always have tiny little fibers stuck to them.