Liberale akzeptanz als kognitiver mechanismus bei psychose: Eine 2-stufen-theorie der pathogenese schizophrener positivsymptome

Positive symptoms, such as delusions and hallucinations, are defining features of psychosis and schizophrenia, respectively. In this review article, we present a 2-stage heuristic model for the formation and maintenance of psychotic positive symptoms. At the heart of our theory is the assumption that individuals with psychosis have a lowered decision threshold resulting in the liberal acceptance of hypotheses. In contrast to non-psychotic persons, confidence in errors is enhanced as a result of liberal acceptance. Two stages are put forward here. At stage 1 (delusion formation), the subjective probability of an accepted hypothesis is relatively low. Delusional ideas at this stage are often fragile and may oscillate between mutually exclusive views ('double book keeping'). During the 2. stage (conviction, maintenance), flighty delusional ideas crystallize due to a 2-fold consolidation process: A) counter-evidence is ignored and b) cues in favor of the dominant hypothesis have a processing advantage (confirmation bias). Alternative hypotheses are degraded in the course of this process. A number of psychological factors and motifs act as maintenance factors, for example the congruence between the delusion and present emotional states, personal importance and the temporary elevation of self-esteem, as well as a superstructure that may explain a broad range of impairments to reduce cognitive dissonance. From our point of view, some forms of hallucinations and first-rank symptoms (e.g., thought broadcasting) can be explained by liberal acceptance as well. These symptoms are not necessarily based on erroneous or abnormal perception but on the misinterpretation of (partially) normal sensory phenomena which evolve from an 'as if' feeling to delusional conviction. In accordance with the model, positive symptoms are decreased by interventions such as metacognitive training (MCT) which encourage individuals with psychosis to search for more information and to reduce their level of certainty (i.e., 'sowing the seeds of doubt'). The antipsychotic properties of antipsychotics/neuroleptics are explained by their potential to induce doubt. The role of emotion regulation for the amelioration of positive symptoms is demonstrated, and further research directions and open questions are outlined.