title: Cognitive variability in psychotic disorders: a cross-diagnostic cluster analysis.
abstract: BACKGROUND
  Cognitive dysfunction is a core feature of psychotic disorders; however, substantial variability exists both within and between subjects in terms of cognitive domains of dysfunction, and a clear 'profile' of cognitive strengths and weaknesses characteristic of any diagnosis or psychosis as a whole has not emerged. Cluster analysis provides an opportunity to group individuals using a data-driven approach rather than predetermined grouping criteria. While several studies have identified meaningful cognitive clusters in schizophrenia, no study to date has examined cognition in a cross-diagnostic sample of patients with psychotic disorders using a cluster approach. We aimed to examine cognitive variables in a sample of 167 patients with psychosis using cluster methods.
  
  
  METHODS
  Subjects with schizophrenia (n = 41), schizo-affective disorder (n = 53) or bipolar disorder with psychosis (n = 73) were assessed using a battery of cognitive and clinical measures. Cognitive data were analysed using Ward's method, followed by a K-means cluster approach. Clusters were then compared on diagnosis and measures of clinical symptoms, demographic variables and community functioning.
  
  
  RESULTS
  A four-cluster solution was selected, including a 'neuropsychologically normal' cluster, a globally and significantly impaired cluster, and two clusters of mixed cognitive profiles. Clusters differed on several clinical variables; diagnoses were distributed amongst all clusters, although not evenly.
  
  
  CONCLUSIONS
  Identification of groups of patients who share similar neurocognitive profiles may help pinpoint relevant neural abnormalities underlying these traits. Such groupings may also hasten the development of individualized treatment approaches, including cognitive remediation tailored to patients' specific cognitive profiles.
authors: Schizophrenia and Bipolar Disorder Program,McLean Hospital,115 Mill Street, Belmont, MA 02478,USA.
authors: K E
authors: KE
authors: Lewandowski
authors: Schizophrenia and Bipolar Disorder Program,McLean Hospital,115 Mill Street, Belmont, MA 02478,USA.
authors: S H
authors: SH
authors: Sperry
authors: Schizophrenia and Bipolar Disorder Program,McLean Hospital,115 Mill Street, Belmont, MA 02478,USA.
authors: B M
authors: BM
authors: Cohen
authors: Schizophrenia and Bipolar Disorder Program,McLean Hospital,115 Mill Street, Belmont, MA 02478,USA.
authors: D
authors: D
authors: Ongür
mesh_terms: D000293:Adolescent; D000328:Adult; D001714:Bipolar Disorder / Q000145:classification* / Q000175:diagnosis / Q000503:physiopathology; D016000:Cluster Analysis; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011618:Psychotic Disorders / Q000145:classification* / Q000175:diagnosis / Q000503:physiopathology; D012559:Schizophrenia / Q000145:classification* / Q000175:diagnosis / Q000503:physiopathology; D055815:Young Adult