Using biological indices to classify schizophrenia and other psychotic patients

• Published in: Schizophrenia research Vol. 50; no. 3; pp. 139 - 150
• Main Authors: Sponheim, S.R, Iacono, W.G, Thuras, P.D, Beiser, M
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.07.2001; Elsevier Science
• Subjects: Adolescent; Adult; Adult and adolescent clinical studies; Biological and medical sciences; Chronic Disease; Cluster Analysis; Electroencephalography; Female; Galvanic Skin Response - physiology; Genetic vulnerability; Humans; Male; Medical sciences; Middle Aged; Nosology; Nosology. Terminology. Diagnostic criteria; Ocular Motility Disorders - diagnosis; Ocular motor function; Other psychotic disorders; Psychiatric Status Rating Scales; Psychology. Psychoanalysis. Psychiatry; Psychopathology. Psychiatry; Psychoses; Psychosis; Psychotic Disorders - classification; Psychotic Disorders - diagnosis; Psychotic Disorders - genetics; Schizophrenia; Schizophrenia - classification; Schizophrenia - diagnosis; Schizophrenia - genetics; Severity of Illness Index; Techniques and methods; Psychosis; Schizophrenia; Nosology; Ocular motor function; Genetic vulnerability; Cluster analysis; Schizoaffective psychosis; Electrodermography; Electrophysiology; Bipolar disorder; First degree relatives; Electroencephalography; Electrodiagnosis; Criterion; Classification; Genetics; Diagnosis; Diagnostic and Statistical Manual IV; Mood disorder; Human; Family study; Biological indicator; Pursuit eye movement; Vision; Perception; Visibility; Schizophreniform disorder; Comparative study
• ISSN: 0920-9964; 1573-2509
• DOI: 10.1016/S0920-9964(00)00160-2

Although classification of mental disorders using more than clinical description would be desirable, there is scant evidence that available laboratory tests (i.e. biological indices) would provide more valid classifications than current diagnostic systems (e.g. DSM-IV). We used cluster analysis of four biological variables to classify 163 psychotic patients and 83 nonpsychiatric comparison subjects. Analyses revealed a three-cluster solution with the first cluster reflecting electrodermal deviance, the second cluster representing nondeviant biological function, and the third cluster reflecting increased nailfold plexus visibility and ocular motor dysfunction. To assess the construct validity of proband clusters we examined ocular motor performance in 156 first-degree relatives as a function of proband cluster membership. First-degree relatives of third cluster probands exhibited worse ocular motor performance than relatives of other cluster probands. Additionally, better classification sensitivity and specificity were obtained for the relatives when they were grouped by proband cluster than by proband DSM-IV diagnosis. When a single proband characteristic (i.e. eyetracking performance) was used to group relatives, classification sensitivity and specificity failed to significantly increase over grouping by proband DSM-IV diagnosis. Multivariate biologically defined clusters may offer an advantage over DSM-IV classification when examining nosology and etiology of psychotic disorders.