title: Visuospatial learning and executive function are independently impaired in first-episode psychosis.
abstract: BACKGROUND
  Demonstrating specific cognitive impairments in psychotic disorders is difficult. However, specific deficits in memory and executive functions have often been claimed. The Cambridge Neuropsychological Test Automated Battery (CANTAB) tasks of IDED attention-shifting (an executive task) and visuospatial paired associates learning (PAL, a memory task) require intact frontal and temporo-hippocampal functioning, respectively; both have been suggested as markers of disease progress in psychosis.
  
  
  METHODS
  Seventy-one subjects with a first-episode psychosis or at-risk mental state were assessed on these two tasks during referral to a specialist service, the Cambridge-based CAMEO early intervention team.
  
  
  RESULTS
  Performance on the two tasks was dissociated. Poor performance on the PAL test was associated with increased symptom levels and poorer global function, while failure on the IDED executive test was not found to have significant clinical associations. Duration of illness was not associated with performance on either task.
  
  
  CONCLUSIONS
  Visuospatial PAL failure may be a marker of clinical severity at the onset of psychosis while IDED performance may reflect a more stable, trait-like impairment. Dissociated performance on the executive and associative learning tasks may reflect independent, neurally dissociated impairments that do not arise in a fixed order. This may explain some of the heterogeneity of cognitive function seen in early psychosis.
authors.affiliation: University of Cambridge Department of Psychiatry, Box 189, Addenbrooke's Hospital, Cambridge CB2 2QQ, UK. jhb32@cam.ac.uk
authors.forename: Jennifer H
authors.initials: JH
authors.lastname: Barnett
authors.forename: Barbara J
authors.initials: BJ
authors.lastname: Sahakian
authors.forename: Ursula
authors.initials: U
authors.lastname: Werners
authors.forename: Katherine E
authors.initials: KE
authors.lastname: Hill
authors.forename: Rossa
authors.initials: R
authors.lastname: Brazil
authors.forename: Olwyn
authors.initials: O
authors.lastname: Gallagher
authors.forename: Edward T
authors.initials: ET
authors.lastname: Bullmore
authors.forename: Peter B
authors.initials: PB
authors.lastname: Jones
mesh_terms: D000328:Adult; D003072:Cognition Disorders / Q000523:psychology*; D005260:Female; D006801:Humans; D007858:Learning; D008297:Male; D008603:Mental Health; D011618:Psychotic Disorders / Q000523:psychology*; D012307:Risk Factors; D013028:Space Perception; D014796:Visual Perception