Abstract
Background
The self-disorder (SD) approach to schizophrenia posits that although schizophrenia involves a core disruption, this alteration nonetheless leaves room for variable experiential pathways toward delusion formation, which are held to account for variation in thematic content. This view of delusions, then, complicates the picture provided by the theory and research that supports MCT, raising the question of how these separate bodies of empirical evidence might be weighed against each other and reconciled. A major point of difference between these two perspectives is on the issue of “normalizing”. Given that the self-disorder approach posits anomalous alterations in self and world experience, the way the patient with schizophrenic delusions is taken as believing is radically different than the individual whose experience cannot be characterized by such anomalous experience. Thus, although the biases posited by MCT may indeed reflect some general and common errors of cognition and reasoning, there is reason to be cautious about interpreting the observation of such biases in the context of schizophrenia as implying that they play the same role as in the development of erroneous beliefs in non-schizophrenic populations. Moreover, while it is of course possible that a specific metacognitive skill taught during a MCT module may nonetheless prove useful for managing delusional ideation, the variable experiential pathways from which different types of delusions emerge may render a given type of delusion as more or less amenable to treatment by means of a specific MCT module and its corresponding metacognitive skill. However, unless MCT studies have thus far considered the relative impact of individual modules on specific types of delusions, the question of which metacognitive skills can be shown as effective for a specific type of delusion remains unknown.
Methods
A scoping review was conducted in order to discern if published MCT studies have examined the impact of individual MCT modules on types of delusions as they occur in the context of schizophrenia spectrum disorders.
Results
It was found that 2% of the 38 MCT studies reviewed provided explicit information about the types of delusions treated, with 5% of such studies reporting on module-specific effects, one study of which specified effects on paranoid delusions.
Discussion
This scoping review is novel in its demonstration that, overall, published MCT studies have not taken into consideration the heterogeneity of delusions, nor have they extensively evaluated whether or not there are differential, module specific, outcomes for different types of delusions. From a phenomenological perspective, this risks ignoring how differences in the thematic content of delusions emerge from differing experiential precursors. How each cognitive and affective mechanism targeted by MCT modules may differently contribute to the maintenance or treatment of different types of delusions will be critically evaluated in consideration of the phenomenology of delusions, and suggestions for further research and practice, which aim toward the goal of individualized medicine, will also be considered.
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