This study sought to determine the specificity of the Calgary Depressi
on Scale (CDS), a depression rating scale for schizophrenics. The spec
ificity is the degree to which the scale assesses depression rather th
an negative or extrapyramidal symptoms. Subjects were 100 outpatients
(OP) and 50 inpatients (IP) meeting DSM-III-R criteria for schizophren
ia. Negative symptoms were assessed with the Positive and Negative Syn
drome Scale (PANSS); extrapyramidal symptoms were assessed with the Si
mpson Angus Scale (SA) and depression with the CDS. Results were that
the CDS showed no correlation with SA, but weak (0.33) statistically s
ignificant correlations with the PANSS negative symptom score in inpat
ients but not outpatients. Confirmatory factor analysis using Lisrel 6
.0 showed that the model hypothesizing specificity of depression, nega
tive symptoms and extrapyramidal symptoms, was significant, with a goo
dness of fit index of 0.89 and a root mean square residual of 0.07. It
is concluded that the CDS achieves a useful degree of separation betw
een measures of depression, negative and extrapyramidal symptoms in su
bjects with schizophrenia, when combined with the other measures used
in this study.