agents
of

The original poster did not say why his mother had been in hospital
but I can answer a few general points.

Elderly patients may exhibit a marked difficulty in coping after
being in hospital for a few days. The drastic change of environment
will often unmask how marginally they have been coping at home. Even
young people find the change unsettling.

Though we have thought that this decrement in function after - say -
anaesthesia and surgery for a fractured hip (a common event in the
elderly) was due to anaesthesia there is good evidence that the
change of situation is much more important. Some hospitals have
tried a 'rapid transit' system for hip fractures, aiming to have the
patient back at home within 24 hours of admission. The selection of
the anaesthetic has no effect on the ability to discharge these
patients early.

Anaesthetists who work with the elderly (which is almost all of us)
generally take care to tailor the choice and dose of drugs used to
the individual patient. Even so, there is some evidence that full
mental recovery may take a surprisingly long time to return. This is
the sort of thing which is detected by setting quite difficult
tasks, not the gross change that the original poster noted.

Haloperidol (Haldol TM) is a long acting drug. The plasma half life
of the drug is up to 35 hours. If the decanoate (a sort of slow
release formulation) is used it may be weeks. The elderly are
sensitive to haloperidol for a number of reasons. Without knowing
more it is hard to comment.