PT  - JOURNAL ARTICLE
AU  - Christina Andreou
AU  - Brooke C. Schneider
AU  - Vivien Braun
AU  - Katharina Kolbeck
AU  - Jürgen Gallinat
AU  - Steffen Moritz
TI  - Dopamine effects on evidence gathering and integration
AID  - 10.1503/jpn.140306
DP  - 2015 Nov 01
TA  - Journal of Psychiatry and Neuroscience
PG  - 422--428
VI  - 40
IP  - 6
4099  - http://jpn.ca/content/40/6/422.short
4100  - http://jpn.ca/content/40/6/422.full
SO  - J Psychiatry Neurosci2015 Nov 01; 40
AB  - Background: Disturbances in evidence gathering and disconfirmatory evidence integration have been associated with the presence of or propensity for delusions. Previous evidence suggests that these 2 types of reasoning bias might be differentially affected by antipsychotic medication. We aimed to investigate the effects of a dopaminergic agonist (L-dopa) and a dopaminergic antagonist (haloperidol) on evidence gathering and disconfirmatory evidence integration after single-dose administration in healthy individuals.Methods: The study used a randomized, double-blind, placebo-controlled, 3-way crossover design. Participants were healthy individuals aged 18–40 years. We administered a new data-gathering task designed to increase sensitivity to change compared with traditional tasks. The Bias Against Disconfirmatory Evidence (BADE) task was used as a measure of disconfirmatory evidence integration.Results: We included 30 individuals in our study. In the data-gathering task, dopaminergic modulation had no significant effect on the amount of evidence gathered before reaching a decision. In contrast, the ability of participants to integrate disconfirmatory evidence showed a significant linear dopaminergic modulation pattern (highest with haloperidol, intermediate with placebo, lowest with L-dopa), with the difference between haloperidol and L-dopa marginally reaching significance.Limitations: Although the doses used for haloperidol and L-dopa were similar to those used in previous studies, drug plasma level measurements would have added to the validity of findings.Conclusion: Evidence gathering and disconfirmatory evidence integration might be differentially influenced by dopaminergic agents. Our findings are in support of a dual-disturbance account of delusions and provide a plausible neurobiological basis for the use of interventions targeted at improving reasoning biases as an adjunctive treatment in patients with psychotic disorders.