Are persistent delusions in schizophrenia associated with aberrant salience?
OBJECTIVE
It has been suggested that positive psychotic symptoms reflect 'aberrant salience'. Previously we provided support for this hypothesis in first-episode schizophrenia patients, demonstrating that delusional symptoms were associated with aberrant reward processing, indexed by the Salience Attribution Test (SAT). Here we tested whether salience processing is abnormal in schizophrenia patients with long-standing treatment-refractory persistent delusions (TRS).


METHODS
Eighteen medicated TRS patients and 31 healthy volunteers completed the SAT, on which participants made a speeded response to earn money in the presence of cues. Each cue comprised two visual dimensions, colour and form. Reinforcement probability varied over one of these dimensions (task-relevant), but not the other (task-irrelevant).


RESULTS
Participants responded significantly faster on high-probability relative to low-probability trials, representing implicit adaptive salience; this effect was intact in TRS patients. By contrast, TRS patients were impaired on the explicit adaptive salience measure, rating high-probability stimuli less likely to be associated with reward than controls. There was little evidence for elevated aberrant salience in the TRS group.


CONCLUSIONS
These findings do not support the hypothesis that persistent delusions are related to aberrant motivational salience processing in TRS patients. However, they do support the view that patients with schizophrenia have impaired reward learning.
Institute of Cognitive Neuroscience, University College London, 17 Queen Square, London, WC1N 3AZ, UK.
Rafeef
R
Abboud
Institute of Cognitive Neuroscience, University College London, 17 Queen Square, London, WC1N 3AZ, UK.
Jonathan P
JP
Roiser
Camden and Islington NHS Foundation Trust, St Pancras Hospital, 4 St. Pancras Way, London, NW1 0PE, UK; Division of Psychiatry, University College London, 6th Floor, Maple House, 149 Tottenham Court Road, London, W1T 7NF, UK; Institute of Psychiatry, Psychology and Neuroscience, Kings College London, De Crespigny Park, London, SE5 8AF.
Hind
H
Khalifeh
Institute of Cognitive Neuroscience, University College London, 17 Queen Square, London, WC1N 3AZ, UK.
Sheila
S
Ali
Camden and Islington NHS Foundation Trust, St Pancras Hospital, 4 St. Pancras Way, London, NW1 0PE, UK; Division of Psychiatry, University College London, 6th Floor, Maple House, 149 Tottenham Court Road, London, W1T 7NF, UK.
Isobel
I
Harrison
Camden and Islington NHS Foundation Trust, St Pancras Hospital, 4 St. Pancras Way, London, NW1 0PE, UK; Division of Psychiatry, University College London, 6th Floor, Maple House, 149 Tottenham Court Road, London, W1T 7NF, UK.
Helen T
HT
Killaspy
Institute of Neurology, University College London, Queen Square, London, WC1N 3BG, UK.
Eileen M
EM
Joyce
Behaviour; Delusions; Psychosis; Reinforcement; Schizophrenia