title: Is processing speed predictive of functional outcome in psychosis?
abstract: OBJECTIVE
  To investigate the contribution of processing speed in the prediction of various domains of outcome in psychosis.
  
  
  METHODS
  Data were drawn from the UK700 Case Management Trial of 708 patients with chronic psychotic illness. Regression analyses were applied to investigate cross-sectional and longitudinal associations between processing speed at baseline and measures of service use, social outcome and subjective outcome, taking into account current psychopathology and adjusting for baseline values of the outcome measure.
  
  
  RESULTS
  Cross-sectionally, processing speed was associated with all three domains of outcome, although only associations in the social and subjective outcome domain remained significant after controlling for psychopathology and the effects differed between and within domains of outcome. Prospectively, only the subjective outcome measure of number of met and unmet needs (CAN) was weakly associated with baseline neurocognitive performance after adjustment for baseline needs. Other associations disappeared after adjustment for the baseline measure of outcome and/or baseline psychopathology.
  
  
  CONCLUSIONS
  The finding of weak cross-sectional associations in the absence of specific and unconfounded longitudinal associations suggests that processing speed is an independent dimension of disease severity rather than a causal factor impacting on social outcome. Nevertheless, longitudinal change in patient reported needs may be weakly sensitive to baseline cognitive impairment.
authors.affiliation: Department of Psychiatry and Neuropsychology, Maastricht University, P.O. BOX 616 (VIJV), 6200 MD, Maastricht, The Netherlands.
authors.forename: Nienke
authors.initials: N
authors.lastname: Jabben
authors.forename: Jim
authors.initials: J
authors.lastname: van Os
authors.forename: Tom
authors.initials: T
authors.lastname: Burns
authors.forename: Francis
authors.initials: F
authors.lastname: Creed
authors.forename: Theresa
authors.initials: T
authors.lastname: Tattan
authors.forename: John
authors.initials: J
authors.lastname: Green
authors.forename: Peter
authors.initials: P
authors.lastname: Tyrer
authors.forename: Robin
authors.initials: R
authors.lastname: Murray
authors.forename: Lydia
authors.initials: L
authors.lastname: Krabbendam
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003071:Cognition; D003430:Cross-Sectional Studies; D005260:Female; D005500:Follow-Up Studies; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008606:Mental Processes; D008875:Middle Aged; D009483:Neuropsychological Tests / Q000706:statistics & numerical data*; D017063:Outcome Assessment, Health Care / Q000706:statistics & numerical data*; D011237:Predictive Value of Tests; D011569:Psychiatric Status Rating Scales; D011618:Psychotic Disorders / Q000175:diagnosis / Q000523:psychology*; D011788:Quality of Life; D012720:Severity of Illness Index; D012917:Social Adjustment; D013997:Time Factors; D006113:United Kingdom