2.2. Elimination of special treatment of bizarre delusions and special
hallucinations
In DSM-IV, only one characteristic symptom is required if it is a bizarre
delusion or a special (Schneiderian first-rank) hallucination.
The note asserting this special treatment is deleted in DSM-5 since
these symptoms have not been found to have diagnostic specificity
and these ‘positive symptoms’ will be treated like any other with regard
to their diagnostic implication. Thus, as with other characteristic
symptoms of psychosis, two criterion A symptoms would need to be
present for a diagnosis of schizophrenia even if one of them is a bizarre
delusion or a specific type of hallucination.
This revision represents a continuation of the change begun in
DSM-IV (Flaum et al., 1998). In DSM-III, Schneiderian first-rank symptoms
received particular prominence in the diagnosis of schizophrenia;
instead of two characteristic symptoms required to meet criterion A for
schizophrenia, just one characteristic symptom was required if that
symptom happened to be a Schneiderian first-rank symptom. This
special treatment of Schneiderian first-rank symptoms (which overlap
with the construct of bizarre delusions and “special” hallucinations) led
to criterion A becoming excessively complex and redundant in DSMIII-
R. In DSM-III-R, there were three separate criteria A (A1 [two or
more characteristic symptoms], A2 [bizarre delusions], and A3 [special
types of hallucinations — Schneiderian first-rank hallucinations]) — the
DSM-IV review found this to be unnecessarily complicated (Flaum et
al., 1998). In DSM-IV, it was decided to retain criterion A2 while folding
the A3 criterion into A2. In DSM-IV, criterion A2 is stated as a criterion
A note that reads: “Only one Criterion A symptomis required if delusions
are bizarre or hallucinations consist of a voice keeping up a running commentary
on the person's thoughts, or two or more voices conversing
with each other.” This is the note being deleted in DSM-5.