Symptom dimensions of the SCL-90-R: a test of the tripartite model of anxiety and depression.

To determine the extent to which the SCL-90-R assesses general distress or specific dimensions of psychopathology, two principal components analyses were conducted based on 900 outpatients diagnosed with mixed psychiatric disorders. The first component explained 30.5% of the total variance and was interpreted as reflecting overall symptom distress. Partialling the first component out of the correlations among the symptoms in a second principal components analysis, we found four specific residual components reflecting somatic anxiety, depression, irritability, and attention problems. The results were discussed as partially supporting Clark and Watson's (1991) tripartite model of anxiety and depression.