What are all possible possessive syntax forms of a word?
For example, "Alzheimer" in a phrase "Dementia in Alzheimer's disease". I know that it is possible to write Alzheimer' or Alzheimer's.
Sometimes, I see people write Alzheimers. Is it correct? Are there other ways?
"Alzheimers disease", rather than "Alzheimer's disease", is technically not correct. There is no other correct way to write it other than "Alzheimer's disease".
"Alzheimers" on its own, without "disease", is used as a colloquial (ie informal) contracted version of "Alzheimer's disease". (eg "My grandma has Alzheimers.") Since it's already informal I'd say that we need to worry less about whether it has an apostrophe, but a quick google reveals that the more official websites keep the apostrophe in the short form too.
The purpose of language is ultimately communication, and so there's no pragmatic reason why you can't call it "Alzheimers disease" - nobody will be confused by the lack of apostrophe. But anyone using it without the apostrophe is using it incorrectly.
SLS Law and Sciences Blog has the article Diseases and Apostrophes – A (Sort of) Poll, which begins:
Many disease names are in the possessive [but they aren't usually named after someone having the disease, ‘Rumplestiltskin’s Disease/Syndrome/XXXoma” etc]. They were all named after the first physician to have described the disease, with only the (informal but, in the US, widespread) exception of Lou Gehrig’s disease (for which, perhaps significantly, there seems to be no “doctor” equivalent – it is formally named after its process, as amyotrophic lateral sclerosis, in the US, or motor neurone disease, in the UK).
A few years ago some disease/patient advocacy groups began arguing that the possessive was inappropriate; the discovering doctors didn’t “own” the disease, which, if “owned” by anyone, should be claimed by its victims. Some authors dropped the apostrophes, others didn’t. (And I faced this question while writing my last post, on Alzheimer(‘)s disease.) Medical journals seem not to have reached any consistent decision, across disease or within diseases.
Note that the result of dropping the apostrophe (by those considering its use inappropriate in these cases) is Alzheimers disease, reflecting the way the word is pronounced (but not traditional possessive/associative structure and logic), not the more normal attributive noun construct Alzheimer disease.
But this treatment of associatives-not-possessives is by no means unprecedented. Dogs homes, childrens clothing departments, working mens clubs etc have been covered here before in the Is it correct to say 'I write children books': not possessive case? Note also Robusto's answer for a medical-domain example at Achilles heel and Achilles tendon:
We don't use an apostrophe [in Achilles heel] because the tendon and heel in question do not belong to Achilles the slayer of Hector in the Iliad, but to someone else.
The apostrophe seems easier to discard here as the s remains naturally, not giving a scary-looking mens, childrens or Alzheimers.
