Functional connectivity of subsystems of the default-mode network in patients with early psychotic symptoms

Abstract

Resting-state connectivity of the default-mode network (DMN) is aberrant in patients with chronic psychotic disorders as well in individuals with early stage psychosis. Studies of the DMN in healthy volunteers revealed that the DMN comprises several subnetworks. However, it is not yet clear if connectivity between and within these DMN subnetworks is aberrant in patients with early psychotic symptoms nor whether these connectivity patterns are related to symptomatology. This initial investigation examined functional connectivity between and within the DMN subnetworks in patients with early psychotic symptoms and in healthy volunteers, and probed how these connectivity patterns were related to the severity of clinical symptomatology. Functional connectivity was measured during resting-state in 30 patients with early psychotic symptoms and in 39 controls using functional MRI. We did not observe differences in connectivity within and between the subnetworks of the DMN between the control group and the early psychosis group. However, lower functional connectivity between the medial prefrontal and posterior medial subnetworks and between medial prefrontal and anterior temporal subnetworks of the DMN did predict the severity of the negative symptoms. The findings of this initial investigation provide insight into the associations between functional connectivity of DMN subnetworks and symptomatology in patients with early psychotic symptoms.

Keywords: Default mode network; Functional connectivity; Psychosis; Psychotic symptoms; Resting-state.

Fig. 1

Nodes of the subnetworks of the DMN: posterior medial (PM; red), anterior temporal (AT; green), medial prefrontal (MPF; blue) represented on a template of standard brain (MNI152) with corresponding z-coordinates.

Fig. 2

Connectivity predicting the severity of negative symptoms. A) Variable inclusion probability of the elastic net penalized regression, with the 70% threshold line. B) Lower connectivity between the MPF and PM and C) lower connectivity between the MPF and AT predicted more severe negative symptoms and together explained 29% of the variance in negative symptoms, R² = 0.29.