Is processing speed predictive of functional outcome in psychosis?
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.
Jabben
Nienke
N
Department of Psychiatry and Neuropsychology, Maastricht University, P.O. BOX 616 (VIJV), 6200 MD, Maastricht, The Netherlands.
van Os
Jim
J
Burns
Tom
T
Creed
Francis
F
Tattan
Theresa
T
Green
John
J
Tyrer
Peter
P
Murray
Robin
R
Krabbendam
Lydia
L
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