Psychotic disorders linked to brain network organisation

US and Canadian researchers have revealed that cognitive impairments in psychotic disorders, such as schizophrenia and bipolar disorder, are linked to brain network organisation. The research has been published in the journal Biological Psychiatry, and comes during an ongoing international effort to identify biomarkers and targets for intervention in individuals at risk for psychotic disorders.

“Cognitive impairment is highly prevalent in schizophrenia and other psychotic disorders,” noted lead author Heather Burrell Ward, MD, from Vanderbilt University Medical Center.

“There are currently no medications to treat cognitive impairment, resulting in significant disability. This impairment is frequently present by the time an individual has their first psychotic break, making early detection and intervention critical. Our current study is part of our work to understand and treat the medication-resistant symptoms of psychotic disorders.”

Several cognitive domains found to be reliably impaired in psychotic disorders have received intensive study, such as overall cognitive ability. To measure cognitive impairment in psychosis, most studies have utilised cognitive tasks originally designed and validated in control populations. However, these studies do not address the question of whether cognitive constructs map onto quantifiable brain substrates. The current research used a cutting-edge MRI analysis approach and a cognitive test designed for people with psychosis to analyse data collected by two consortia of researchers: the Human Connectome Project for Early Psychosis (HCP-EP) and the North American Prodrome Longitudinal Study (NAPLS).

“We observed that in individuals with psychotic disorders, cognitive impairment is linked to brain network organisation,” said co-author Roscoe O Brady Jr, PhD, from Harvard Medical School. “We then attempted something that has not been previously demonstrated: we asked if we can observe this same brain signature of cognitive impairment in individuals prior to their psychotic break.

“We analysed data from individuals considered at risk for psychotic disorders, but who had not yet had their first psychotic episode. We identified this same brain network–cognition relationship only in individuals who would eventually develop psychosis in the future.”

Co-senior author Kathryn E Lewandowski, PhD, from McLean Hospital and Harvard Medical School, concluded, “Our discovery of a link between cognition and brain networks, observed even prior to the first psychotic break, suggests an opportunity for early diagnosis and intervention, such as via non-invasive neuromodulation.”

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