Studies have consistently shown an association between cognitive biases, such as jumping to conclusions (e.g., Moritz & Woodward, 2005) or overconfidence in errors (Moritz et al., 2006a; Moritz et al., 2008; Moritz et al., 2006b), with positive symptoms of schizophrenia. Moreover, disturbances in the processing of contextual information have been associated with disorganization symptoms in schizophrenia (Andreou et al., 2009; Moritz et al., 2001; Moritz et al., 2003a). However, it is not yet clear how these (meta)cognitive dysfunctions relate to the neurobiological markers of the illness, especially to the dopaminergic hyperactivity postulated to underlie psychotic symptoms. Using experimental paradigms, our studies aim to systematically assess the effects of dopaminergic agonists and antagonists that are associated with the positive and disorganized symptoms of schizophrenia. For this purpose, healthy individuals are tested after administration of L-Dopa, haloperidol, or placebo. Our initial results indicate that distinct cognitive biases are differentially modulated by dopaminergic manipulation (Andreou et al., 2014a). Antipsychotics appear to dampen overconfidence, particularly in relation to errors (Andreou et al., 2014a; Moritz et al., 2003b; Moritz et al., 2013), but not the jumping-to-conclusions bias (Andreou et al., 2014a), suggesting that delusions might arise from the interplay among various factors rather than from a single cognitive mechanism. In addition, our work on disorganized speech has demonstrated that dopaminergic modulation affects semantic priming in a manner consistent to that expected based on clinical observations, providing strong evidence for a link between dopaminergic activity and the cognitive substrate of disorganized speech (Andreou et al., 2014b).
- PD Dr. Christina Andreou
- Katharina Kolbeck, M.Sc.
- Prof. Dr. Steffen Moritz
- PD Dr. med. Knut Schnell
- Dr. Ruth Veckenstedt
- Dr. Kirsten Guba
Andreou, C., Moritz, S., Veith, K., Veckenstedt, R. & Naber, D. (2014a). Dopaminergic modulation of probabilistic reasoning and overconfidence in errors: A double-blind study. Schizophrenia Bulletin, 40, 558-565.
Andreou, C., Veith, K., Bozikas, V. P., Lincoln, T. M. & Moritz, S. (2014b). Effects of dopaminergic modulation on automatic semantic priming: A double-blind study. Journal of Psychiatry & Neuroscience, 39, 110-117.
Andreou, C., Tsapkini, K., Bozikas, V. P., Giannakou, M., Karavatos, A. & Nimatoudis, I. (2009). Effects of sentence context on lexical ambiguity resolution in patients with schizophrenia. Neuropsychologia, 47, 1079-1087.
Moritz, S., Andreou, C., Klingberg, S., Thöring, T. & Peters, M. J. V. (2013). Assessment of subjective cognitive and emotional effects of antipsychotic drugs. Effect by defect? Neuropharmacology, 72, 179-186.
Moritz, S., Mersmann, K., Kloss, M., Jacobsen, D., Andresen, B., Krausz, M., Pawlik, K. & Naber, D. (2001). Enhanced semantic priming in thought-disordered schizophrenic patients using a word pronunciation task. Schizophrenia Research, 48, 301-305.
Moritz, S. & Woodward, T. S. (2005). Jumping to conclusions in delusional and non-delusional schizophrenic patients. British Journal of Clinical Psychology, 44, 193-207.
Moritz, S., Woodward, T. S. & Hausmann, D. (2006a). Incautious reasoning as a pathogenetic factor for the development of psychotic symptoms in schizophrenia. Schizophrenia Bulletin, 32, 327-331.
Moritz, S., Woodward, T. S., Jelinek, L. & Klinge, R. (2008). Memory and metamemory in schizophrenia: A liberal acceptance account of psychosis. Psychological Medicine, 38, 825-832.
Moritz, S., Woodward, T. S., Kuppers, D., Lausen, A. & Schickel, M. (2003a). Increased automatic spreading of activation in thought-disordered schizophrenic patients. Schizophrenia Research, 59, 181-186.
Moritz, S., Woodward, T. S. & Rodriguez-Raecke, R. (2006b). Patients with schizophrenia do not produce more false memories than controls but are more confident in them. Psychological Medicine, 36, 659-667.
Moritz, S., Woodward, T. S. & Ruff, C. C. (2003b). Source monitoring and memory confidence in schizophrenia. Psychological Medicine, 33, 131-139.