Doctors call it “pharyngitis”, because they need to be specific in their documents. Normal people just call it “sore throat”, because that’s close enough and easy to understand. Same thing should apply to various brain disorders too.

If you aren’t writing to medical professionals, go with whatever description you understand better. It’s going to be easier for everyone involved.

If you’re in America, you should look up the relevant TLA and use that instead. Every American seems to be born with the innate ability to know all of them, so it’s just as good as using the easily understandable two word description.

The fewer syllables you use, the fewer words you can make. There are too many disorders out there to give them all simple names in an unambiguous way.

Is "senile" not simple enough for you? The problem is, it's maligned because its too loosely applied and becomes used as an insult. So it's really a no-win scenario. Make it too simple and it becomes clinically useless and people will throw it around like an insult, make it too complex and it becomes only useful in clinical settings and average people can't remember it. Is there a middle ground? I'm not sure. Alzheimer's and dementia/demented are kind of in the middle, but they both get used inappropriately and are clinically useless, so they end up being a worst of both worlds.

That’s a type of dementia.

So the answer the question is they do.

It gets worse, e.g. aibohphobia (the fear of palindromes). Sufferers can't seek treatment because they're afraid to even say its name.

This is a big problem with medicine in general. Medicine is unfortunately very much an old white man's club, it's getting better slowly, but all the knowledge and the way it is taught comes from that old white guy standard.

Medical terminology is complex because medicine is complex. There is definitely an element of being part of an exclusive club but there is also communicating lots of information quickly and efficiently.

Frontotemporal dementia describes a specific set of symptoms and if you are medically trained tells you most everything you need to know about what is happening. As opposed to the patient is a bit confused or sees things sometimes which could be many different things.

The language and how diagnoses are communicated are really important, a good medic should tell the patient their diagnosis with the medical words but should explain what those mean in as much detail as the patient wants.

Most patients are able to understand dementia even if the frontotemporal bit doesn't make sense to them.