Brain network disruption crosses psychosis diagnostic boundaries

By Eleanor McDermid, Senior medwireNews Reporter

Disruption of cortical information processing occurs in patients with psychosis regardless of whether they have a psychotic or affective diagnosis, research shows.

“Our analyses identified a pattern of disrupted connectivity consistent with pronounced disruption of the frontoparietal control network and with less marked aberrant connectivity within and across other networks,” say lead study author Justin Baker (McLean Hospital, Belmont, Massachusetts, USA) and colleagues.

The researchers compared functional magnetic resonance imaging data of 100 mentally healthy controls and 100 patients with a psychotic diagnosis: 28 with schizophrenia; 32 with schizoaffective disorder; and 40 who had bipolar disorder with psychosis.

“Our analysis included all resting-state networks rather than being restricted to a limited number of a priori regions and networks,” they comment in JAMA Psychiatry.

Across the possible 3660 intrahemispheric regional interactions, 97 (2.7%) significantly differed between patients and controls, after accounting for age, gender, race, handedness, and scan quality. Of these differences, 34 were psychosis-related reductions in correlation, and 33 of these reductions were between regions within the same network.

The other 63 psychosis-related differences showed increased correlations, and all occurred between networks. All these regions had negative correlations at rest (ie, increased activation in one region is associated with decreased activation in the other), so this negative correlation was reduced in patients with psychosis.

The differences were most marked in the frontoparietal control network, particularly in one section the team refers to as the “control B network,” in which 12 of a possible 20 interactions had significantly reduced correlation relative to that in controls.

Previous research suggests that the highest-order tasks activate areas equivalent to this control B territory, say Baker et al, meaning the dysfunction seen in this study “matches well with the core deficits observed” in patients with psychosis.

Disrupted connectivity was not associated with clinical symptoms, which the researchers say could be because of the heterogeneity of the study sample, or because the impairments represent a trait characteristic, rather than being related to current symptoms.

“Our results suggest that psychosis is associated with a disruption in the control architecture needed to mediate between modes of information processing, possibly resulting in inappropriate activation of other networks, including the default network,” the team concludes.

“This disruption might lead to blurring of the normally strongly defined boundary between internally and externally oriented processing.”

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