Delusion formation and reasoning biases in those at clinical high risk for psychosis.
BACKGROUND
Cognitive models propose that faulty appraisal of anomalous experiences is critical in developing psychosis, particularly delusions. A data gathering bias may be fundamental to abnormal appraisal.


OBJECTIVE
To examine whether there is a data gathering bias in people at high risk of developing psychosis.


METHODS
Individuals with an at-risk mental state (n=35) were compared with a matched group of healthy volunteers (n=23). Participants were tested using a modified version of the 'beads' reasoning task with different levels of task difficulty.


RESULTS
When task demands were high, the at-risk group made judgements on the basis of less information than the control group (P<0.05). Within both groups, jumping to conclusions was directly correlated with the severity of abnormal beliefs and intolerance of uncertainty (P<0.05). In the at-risk group it was also associated with impaired working memory (P<0.05), whereas in the control group poor working memory was associated with a more conservative response style (P<0.05).


CONCLUSIONS
People with an at-risk mental state display a jumping to conclusions reasoning style, associated with impaired working memory and intolerance of uncertainty. This may underlie a tendency to develop abnormal beliefs and a vulnerability to psychosis.
Section of Neuroimaging, Division of Psychological Medicine, Institute of Psychiatry, London, UK. m.broome@iop.kcl.ac.uk
M R
MR
Broome
L C
LC
Johns
I
I
Valli
J B
JB
Woolley
P
P
Tabraham
C
C
Brett
L
L
Valmaggia
E
E
Peters
P A
PA
Garety
P K
PK
McGuire
D000328:Adult; D003702:Delusions / Q000209:etiology* / Q000523:psychology; D006801:Humans; D007175:Impulsive Behavior / Q000523:psychology; D007360:Intelligence; D007600:Judgment; D008570:Memory, Short-Term; D009483:Neuropsychological Tests; D011340:Problem Solving; D011569:Psychiatric Status Rating Scales; D011618:Psychotic Disorders / Q000523:psychology*