In my opinion your example is poorly chosen. People with ulcers already knew they had ulcers before Barry J. Marshall and J. Robin Warren earned the Nobel Prize in Medicine for discovering the infectious cause, and thereby pinpointing an effective treatment.
Who would want to be told at age 30 “You have early Alzheimers, but we don’t have a good treatment yet.”? I think just about nobody.
In my opinion Dr Frederick Klenner had the correct approach: give the patient lots of vitamin C while you ponder the diagnosis.
See movie “ Still Alice “…..very good .
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The patient comes in with a complaint. At that point, no one knows the answer. The workup leads to a diagnosis, but you don’t know it before you start.
Are you going to lie to the patient if the dx is early Alzheimers? Do you say you don’t know, which is also a lie? Most folks don’t like being lied to. Do you like being lied to?