Psychiatric syndromes from a clinical and a biostatistical point of view.

Syndromes are typical combinations of symptoms. They may be conceived at different levels of complexity, intuitively from a clinical point of view and objectively by means of factor- or cluster-analyses. Primary factors of symptom scores obtained with the aid of psychiatric rating scales represent syndromes of low complexity, secondary factors represent syndromes of higher complexity. The highest level is achieved by rotating only the first factors extracted from the matrix of intercorrelations among primary factors of psychopathology. Principal component analysis of 12 Inpatient Multidimensional Psychiatric Scale factors that reflect the psychopathological states at admission of 1,080 psychotic inpatients yielded the highly complex endogenomorphic syndromes of schizophrenic and manic-depressive symptomatology, respectively, in a two-factor solution. These syndromes were cut down to lower order syndromes in the four-factor solution resulting from rotation according to the conventional Kaiser criterion. They represent a syndrome of psychotic excitement, a paranoid-hallucinatory syndrome, a syndrome of endogenomorphic (retarded) depression and a syndrome of organic symptomatology. The different factor solutions may be useful for describing psychopathological phenoma objectively at different levels of complexity.