The letter to the co-op board sounds likely enough. The tenant is up in arms because air fresheners and other common household odors are seeping into the writer's apartment, giving him severe migraines. What to do about this chemical onslaught?
There's no doubt that these odors are giving the letter writer a debilitating headache, but also little doubt that there isn't a likely double-blind, testable, organic chemistry cause to the headache only in this setting.
The migraine in this case, like many things that bother us, is caused by a nocebo.
A nocebo is a placebo that makes things worse.
In this case, the lack of control over his home, the unwelcome and unasked for odors, are making him feel trapped, and thus annoyed, and angry, and so they lead to a headache. It's pretty clear to most of us that if that very same bundle of molecules wafted in the door when the clever and happy grandson came to visit, there would be no problem.
Of course the nocebo is real. And eliminating it is a great way to improve your life or the lives of your customers.
The TSA intentionally brings a nocebo to the airport, stressing out innocent travelers. And schools know precisely how to raise the blood pressure of stressed out students. In many situations, loud noises, uncomfortable seats, moments of lost control... these create actual physical discomfort.
We can use the nocebo to give you a headache, a backache, or even a chronic degenerative disease...
But you don't remove the nocebo with medical tests. You remove it with a better story, with a situation that makes us feel powerful and in control, with a setting and a narrative that gives us agency and dignity.
[I'm not asserting that all migraines are caused by nocebos. Far from it. I apologize to anyone who got that impression. But there's plenty of evidence that there are very real problems caused by nocebos.]