Reviewing Brief Psychiatric Rating Scale (BPRS) research indicates tha
t combining items to form larger 'symptom factors' (e.g., depression,
psychosis) has become the standard methodology. Unfortunately, a singl
e symptom factor may be defined by different combinations of different
BPRS items in different studies. To examine the potential impact of t
hese differences, a number of different BPRS definitions of positive a
nd negative symptoms in schizophrenia were culled from previous resear
ch. To compare these definitions, one hundred schizophrenics were inte
rviewed with regard to current and recent symptomatology and rated on
the BPRS, the Schedule for the Assessment of Negative Symptoms (SANS),
and the Schedule for the Assessment of Positive Symptoms (SAPS). The
four BPRS negative symptom definitions all correlated highly with one
another and with the SANS. There were no differences in the amount tha
t these different definitions of negative symptoms correlated with the
SANS. Also, the nine definitions of positive symptoms all correlated
highly with one another and with the SAPS. However, there were signifi
cant differences in how they correlated with the SAPS. Because of thes
e differences, possible standard definitions for negative and positive
symptoms of schizophrenia are proposed for future use of the BPRS in
research.