This article is more than 5 years old. Information may no longer be current.

MRI shows schizophrenia-related brain abnormalities in individuals at high risk for psychosis

Thalamic dysconnectivity, similar to that observed in patients with schizophrenia, was observed among individuals at high risk for psychosis and was more pronounced among those who eventually progressed to a psychosis diagnosis, and was associated with symptom severity.

“Several groups have recently reported disrupted thalamocortical functional connectivity in chronic schizophrenia. However, schizophrenia is a neurodevelopmental illness associated with brain abnormalities that likely occur before onset of all clinical symptoms. Currently, it is unknown whether thalamocortical dysconnectivity emerges exclusively in association with chronic illness or whether high clinical risk and subsequent longitudinal conversion to full-blown illness, as opposed to non-conversion, are also associated with functional thalamocortical disruptions,” Alan Anticevic, PhD, of Yale University, and colleagues wrote.

To assess differences in baseline thalamocortical connectivity between individuals at clinical high risk for psychosis and healthy controls and whether these differences were more severe in those who later convert to full-blown illness, researchers evaluated 397 individuals aged 12 to 35 years. Of these, 243 were at clinical high risk for psychosis, of which 21 converted to full-blown illness. The remaining 154 were healthy controls. Researchers used study participants’ anatomically defined thalamic seeds, measured during resting-state functional connectivity MRI, to establish whole-brain thalamic functional connectivity maps.

MRI identified thalamocortical dysconnectivity in all of the individuals at clinical high risk for psychosis, including the 21 who progressed to full-blown psychosis. These participants exhibited widespread hyperconnectivity between the thalamus and prefrontal and cerebellar areas, which was more pronounced among those who progressed to full-blown illness (P < .001).

Individuals with thalamocortical dysconnectivity also showed thalamic hyperconnectivity with sensory motor areas. This pattern was also more pronounced among those who progressed to full-blown illness (P < .001).

Both patterns were significantly associated with concurrent prodromal symptom severity, according to researchers.

“This finding is of great neurobiological relevance because it can be conceptually integrated with the other core neuroimaging abnormalities observed in [clinical high risk] patients: elevated dopamine function, abnormal glutamate levels, and alterations in prefrontal cortex and medial temporal lobe structure and function. The interaction of all these abnormalities during psychosis onset can be addressed by neurobiological models that propose that psychosis develops as a result of a perturbation of medial temporal lobe function, leading to elevated striatal dopamine function (methylazoxymethanol acetate model),” Paolo Fusar-Poli, MD, PhD, RCPsych, of King’ College London, wrote in an accompanying editorial. “The near decade will be crucial to definitively tell us whether and to what extent the translational promises of [these] findings and of neuroimaging methods in early psychosis have been kept.” – by Amanda Oldt

Disclosure: The researchers report no relevant financial disclosures.