Symptoms of schizophrenia. Methods, meanings, and mechanisms.
BACKGROUND
The "group of schizophrenias," normally referred to with a single nominative, is phenomenologically heterogeneous. Its symptoms represent multiple psychological domains, including perception, inferential thinking, language, attention, social interaction, emotion expression, and volition. Studies of psychopathology have simplified this complex array in several ways, one of which is a subdivision into positive and negative symptoms.


METHODS
This study examined the positive vs negative distinction in a sample of 243 patients with schizophrenia or schizophreniform disorder who were evaluated with the Scale for the Assessment of Negative Symptoms and the Scale for the Assessment of Positive Symptoms. A two-stage factor analysis was applied, beginning with a principal components analysis applying varimax rotation, followed by an extension analysis. The purpose of these analyses was to evaluate the correlational relationships of the various symptoms of schizophrenia.


RESULTS
The results confirmed previous reports by our group and others suggesting that the symptoms of schizophrenia fall into three natural dimensions, as assessed by the correlational interrelationships: positive symptoms subdivide into psychotic and disorganized dimensions, while a third negative dimension also emerges.


CONCLUSIONS
Because these dimensions have impressive consistency across studies, future work must examine their relationship to clinically relevant concepts such as prognosis or etiology and examine four different aspects: longitudinal course, neural mechanisms, relationship to treatment, and interrelationships in other pathological conditions.
Andreasen
N C
NC
Mental Health Clinical Research Center, University of Iowa Hospitals and Clinics, College of Medicine, Iowa City, USA.
Arndt
S
S
Alliger
R
R
Miller
D
D
Flaum
M
M
D017668:Age of Onset; D001714:Bipolar Disorder / Q000175:diagnosis / Q000523:psychology; D003866:Depressive Disorder / Q000175:diagnosis / Q000523:psychology; D003937:Diagnosis, Differential; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D016013:Likelihood Functions; D008297:Male; D008959:Models, Neurological; D008960:Models, Psychological; D015233:Models, Statistical; D011569:Psychiatric Status Rating Scales / Q000706:statistics & numerical data; D011618:Psychotic Disorders / Q000175:diagnosis / Q000523:psychology; D012559:Schizophrenia / Q000145:classification / Q000175:diagnosis*; D012565:Schizophrenic Psychology; D012569:Schizotypal Personality Disorder / Q000175:diagnosis / Q000523:psychology; D009626:Terminology as Topic