Sometimes you have to drop a particular style in favour of another. As many users have already mentioned, there is no verb in English which means "knowledge of one's existence". The terms id (the part of the mind in which innate instinctive impulses and primary processes are manifest), ego, and superego are sometimes used in connection with Alzheimer.
... manifestations become murky as the clinical course of Alzheimer's disease advances. Generally, ego dysfunction is considerably more apparent than superego ...
Those at endstage dementia have been regarded psychodynamically as experiencing a complete breakdown of the ego and its defences with apparent reciprocal dedifferentiation of the id.
However, it's my understanding that these Freudian terms have become dated, and not everyone agrees with their definitions. But don't quote me on that.
A newly coined term, “aware ego” (The Neurobiology
of the Aware Ego) appears to have replaced Freud's Id, Ego and Superego, but I don't know how common or well-known this expression is. In the same medical article, the term anosognosia (lack of self awareness) is used.
Instead, may I suggest a different solution which covers all five of the above, and is easily understandable; identity loss. Google Scholar has about 58,600 hits for Alzheimer's identitiy loss (without speech marks). Swapping verbs with nouns would lead to this formation.
They lose their memory. Their understanding. Their identity