The ICD/DSM schizophrenia diagnosis is a ill-defined phenotype. The Wernicke-Kleist-Leonhard school distinguish 35 major phenotypes in the psychotic spectrum. Among them, the cycloid psychoses (CP, remitting forms) and affect laden paraphrenia (ALP, the core of paranoid schizophrenia) appear promising. We used a resting state functional connectivity analysis to find commonalities and differences between these 2 groups.
Seventeen patients with CP and 17 with ALP all fulfilling DSM-IV defined schizophrenia were recruited together with 57 controls. Participants took part to a 20 min resting state fMRI scan keeping eyes closed but remaining awake. The signal from the 78 Brodman areas was averaged and a correlation coefficient was the metric for functional connectivity between them. Groups were compared using permutation test corrected for multiple testing.
CP and ALP commonly differed from controls by a disconnection of their temporal regions (internal temporal, the temporal pole, the inferior temporal - in black). But CP had an increase of connectivity between the same temporal regions relative to both ALP and controls. Conversely ALP had a much larger disconnectivity pattern relative to both CP and controls including the cingulate and the orbito-frontal regions as a whole (in white).
CP and ALP share temporal disconnectivity which could be correlated with psychosis proneness. However the reasons for it appear different in the two groups: an excess of intra-temporal connectivity in CP, a more global and widespread decrease of connectivity in ALP which correlate with the type of residual symptoms observed in this group.