title: Can cognitive deficits differentiate between schizophrenia with and without obsessive-compulsive symptoms?
abstract: BACKGROUND
  The frequent occurrence of obsessive-compulsive symptoms (OCS) in the course of schizophrenia and their impact on the functional outcome of the illness underlie the suggestion that the presence of OCS represents a separate subtype of schizophrenia, with a distinct clinical presentation and prognosis and specific neurobiological characteristics. This study investigated whether the presence of OCS in schizophrenia is associated with worse cognitive functioning in the domains of processing speed, executive functions and visuospatial memory. We also explored whether the degree of impairment in any of these cognitive domains could predict group membership (i.e. Schizophrenia with OCS [Sch-OCS] and Schizophrenia without OCS) and if there was a relationship between cognitive functioning and severity of OCS within the Sch-OCS group.
  
  
  METHODS
  Forty patients with schizophrenia, 20 with and 20 without OCS, individually matched for age, gender, years of education and severity of psychotic symptoms and 20 healthy controls underwent a comprehensive neuropsychological assessment.
  
  
  RESULTS
  Only lower performance in processing speed discriminated patients with OCS from patients without OCS. Processing speed impairment not only classified patients in OCS or non-OCS group but was also independent of the severity of OCS symptoms.
  
  
  CONCLUSIONS
  The notion of additive effects of both schizophrenia and OCD on the structural and functional integrity of the brain circuits that support cognitive functions warrants further investigation in longitudinal neuropsychological and neuroimaging studies with larger samples and sufficient variation in the severity of OCS.
authors.affiliation: Section of Schizophrenia, Imaging and Therapeutics, Department of Psychosis studies, Institute of Psychiatry, King's College London, UK; Second Department of Psychiatry, Athens University Medical School, Greece. Electronic address: panayiota.michalopoulou@kcl.ac.uk.
authors.forename: Panayiota G
authors.initials: PG
authors.lastname: Michalopoulou
authors.affiliation: First Department of Psychiatry, Athens University Medical School, Greece; Section of Cognitive Neuropsychiatry, Department of Psychosis studies, Institute of Psychiatry, King's College London, UK.
authors.forename: George
authors.initials: G
authors.lastname: Konstantakopoulos
authors.affiliation: First Department of Psychiatry, Athens University Medical School, Greece.
authors.forename: Maria
authors.initials: M
authors.lastname: Typaldou
authors.affiliation: First Department of Psychiatry, Athens University Medical School, Greece.
authors.forename: Charalambos
authors.initials: C
authors.lastname: Papageorgiou
authors.affiliation: First Department of Psychiatry, Athens University Medical School, Greece.
authors.forename: George N
authors.initials: GN
authors.lastname: Christodoulou
authors.affiliation: Second Department of Psychiatry, Athens University Medical School, Greece.
authors.forename: Lefteris
authors.initials: L
authors.lastname: Lykouras
authors.affiliation: First Department of Psychiatry, Athens University Medical School, Greece.
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Oulis
mesh_terms: D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D003072:Cognition Disorders / Q000150:complications* / Q000523:psychology*; D056344:Executive Function; D005260:Female; D006801:Humans; D008297:Male; D008568:Memory; D008875:Middle Aged; D009483:Neuropsychological Tests; D009771:Obsessive-Compulsive Disorder / Q000150:complications* / Q000175:diagnosis*; D011237:Predictive Value of Tests; D011930:Reaction Time; D012559:Schizophrenia / Q000150:complications* / Q000175:diagnosis*; D012565:Schizophrenic Psychology; D055815:Young Adult