A double dissociation between two psychotic phenotypes: Periodic catatonia and cataphasia

Schizophrenia as a single liability model was confronted to the multiple psychotic phenotypes model proposed by the Wernicke-Kleist-Leonhard school, focusing on two: periodic catatonia (PC) and cataphasia (C). Both are stable and heritable psychotic phenotypes with no crossed liability and are coming with the buildup of specific residual symptoms: impairment of psychomotricity for PC and a specific disorganization of thought and language in C. Regional cerebral blood flow (rCBF) was used as a biomarker. We attempted to refute the single phenotype model by looking at relevant and specific rCBF anomalies for PC and C, that would exceed anomalies in common relative to controls (CTR), i.e. looking for a double dissociation. Twenty subjects with PC, 9 subjects with C and 27 matched controls had two MRI QUIPSS II arterial spin labeling sequences converted in rCBF. One SPM analysis was performed for each rCBF measurement and the results were given as the conjunction of both analysis. There was a clear double dissociation of rCBF correlates between PC and C, both being meaningful relative to their residual symptomatology. In PC: rCBF was increased in the left motor and premotor areas. In C: rCBF was decreased bilaterally in the temporo-parietal junctions. Conversely, in both (schizophrenia): rCBF was increased in the left striatum which is known to be an anti-psychotics' effect. This evidence refuts the single schizophrenia model and suggests better natural foundations for PC and C phenotypes. This pleads for further research on them and further research on naturally founded psychotic phenotypes.