I think he is delusional. I don't know if that is a precursor to dementia or not.
http://ageing.oxfordjournals.org/content/25/5/405.full.pdf
The definition of a delusion is 'a false, unshakeable idea
or belief ... held with extraordinary conviction and
subjective certainty' [1]. Delusions are a common
symptom of a range of psychiatric illnesses including
schizophrenia, depression, bipolar disorder and
dementia.
I'm guessing he is more towards dementia than anything.
schizophrenia is like word salad.
depression, he doesn't seem to exhibit any sadness, or defeatism, or whatever...
bipolar disorder, he hasn't gone manic or anything.
he is almost demented in the sense that he is not consistent and is all over the place from one day to the next with really, nothing solid.