We have an older cat been in our family all its life.  She is a Calico and
about 18.

Mostly at night she will wander the house making a strange and loud meow
(almost like cats sound when they are mating or fighting).  She will stop
meowing when she sees us.  Then a few minutes later starts again.  I have
seen her in a dark corner meowing like this too...like she is lost.

She will purr after some attention and seems to have an appetite abiet not
as much as when she used to and does seem to be much more picky about what
she will eat.  She is also drinking from the toilet lately which she has
never done before (an on one occasion fell in in the middle of the night,
that screech I do recoginize!).

She is deaf now too (this happended slowing after a teeth cleaning...dont
know if related to deafness).

Any thoughts about whats up with her?  Is she suffering from some sort of
feline dimensia?

thanks for any thoughts