A canon of medicine holds that when one disease can
account for symptoms attributed to several, there is usually
only one: in this case, there is substantial support for
the hypothesis that the disease is a psychotic mood disorder.
However, paranoid schizophrenia remains the
most common subtype, and paranoia has been said to
be ubiquitous in all subtypes of schizophrenia,46 but
‘‘paranoid’’ delusions in functionally psychotic patients