Recent studies have consistently shown an association of cognitive biases, such as jumping to conclusions (Moritz & Woodward, 2005) or overconfidence in errors (Moritz, Woodward, & Hausmann, 2006; Moritz, Woodward, Jelinek, & Klinge, 2008; Moritz, Woodward, & Rodriguez-Raecke, 2006), with positive symptoms of schizophrenia. Moreover, disturbances in the processing of contextual information (e.g., in the language domain) have been associated with disorganization symptoms in patients with schizophrenia (Andreou et al., 2009; Moritz et al., 2001; Moritz, Woodward, Kuppers, Lausen, & Schickel, 2003). However, it is not yet clear how these (meta)cognitive dysfunctions relate to the known 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 have consistently been reported to correlate with the positive and disorganized symptoms of schizophrenia. For this purpose, healthy individuals are tested after administration of L-Dopa, haloperidol, or placebo. The study will hopefully provide new insights into the biopsychopathological processes underlying the core symptoms of schizophrenia as well as aid the development of therapeutic interventions targeting dopamine-related cognitive processes.
Our first results indicate that different cognitive biases are differentially modulated by dopaminergic manipulation (Andreou, Moritz, Veith, Veckenstedt, & Naber, 2014). Antipsychotics appear to dampen overconfidence, particularly in relation to errors (Andreou, Moritz, et al., 2014; Moritz, Woodward, & Ruff, 2003; Moritz, Andreou, Klingberg, Thöring, & Peters, 2013), but not the jumping-to-conclusions bias (Andreou, Moritz, et al., 2014), suggesting that delusions might arise from the interplay among various factors rather than from a single cognitive mechanism. In contrast, 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, Veith, Bozikas, Lincoln, & Moritz, 2014). Additionally, in cooperation with the University of Heidelberg, we are currently investigating the effects of dopaminergic agents on other symptom-relevant cognitive functions, such as action monitoring (associated with passivity symptoms).
- PD Dr. Christina Andreou
- cand. psych. Vivien Braun
- Dr. Kirsten Guba
- Katharina Kolbeck, M.Sc.
- Prof. Dr. Steffen Moritz
- PD Dr. Knut Schnell
- Dr. Ruth Veckenstedt
Andreou, C., Moritz, S., Veith, K., Veckenstedt, R., & Naber, D. (2014). 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. (2014). Effects of dopaminergic modulation on automatic semantic priming: A double-blind study. Journal of Psychiatry and 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. (2006). 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. (2003). Increased automatic spreading of activation in thought-disordered schizophrenic patients. Schizophrenia Research, 59, 181-186.
Moritz, S., Woodward, T. S., & Rodriguez-Raecke, R. (2006). 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. (2003). Source monitoring and memory confidence in schizophrenia. Psychological Medicine, 33, 131-139.