Association of Thalamic Dysconnectivity and Conversion to Psychosis in Youth and Young Adults at Elevated Clinical Risk

Abstract

IMPORTANCESevere neuropsychiatric conditions, such as schizophrenia, affect distributed neural computations. One candidate system profoundly altered in chronic schizophrenia involves the thalamocortical networks. It is widely acknowledged that schizophrenia is a neurodevelopmental disorder that likely affects the brain before onset of clinical symptoms. However, no investigation has tested whether thalamocortical connectivity is altered in individuals at risk for psychosis or whether this pattern is more severe in individuals who later develop full-blown illness.OBJECTIVES To determine whether baseline thalamocortical connectivity differs between individuals at clinical high risk for psychosis and healthy controls, whether this pattern is more severe in those who later convert to full-blown illness, and whether magnitude of thalamocortical dysconnectivity is associated with baseline prodromal symptom severity. DESIGN, SETTING, AND PARTICIPANTSIn this multicenter, 2-year follow-up, case-control study, we examined 397 participants aged 12-35 years of age (243 individuals at clinical high risk of psychosis, of whom 21 converted to full-blown illness, and 154 healthy controls). The baseline scan dates were January 15, 2010, to April 30, 2012. MAIN OUTCOMES AND MEASURESWhole-brain thalamic functional connectivity maps were generated using individuals' anatomically defined thalamic seeds, measured using resting-state functional connectivity magnetic resonance imaging.RESULTS Using baseline magnetic resonance images, we identified thalamocortical dysconnectivity in the 243 individuals at clinical high risk for psychosis, which was particularly pronounced in the 21 participants who converted to full-blown illness. The pattern involved widespread hypoconnectivity between the thalamus and prefrontal and cerebellar areas, which was more prominent in those who converted to full-blown illness (t 173 = 3.77, P < .001, Hedge g = 0.88). Conversely, there was marked thalamic hyperconnectivity with sensory motor areas, again most pronounced in those who converted to full-blown illness (t 173 = 2.85, P < .001, Hedge g = 0.66). Both patterns were significantly correlated with concurrent prodromal symptom severity (r = 0.27, P < 3.6 × 10 −8 , Spearman ρ = 0.27, P < 4.75 × 10 −5 , 2-tailed).CONCLUSIONS AND RELEVANCE Thalamic dysconnectivity, resembling that seen in schizophrenia, was evident in individuals at clinical high risk for psychosis and more prominently in those who later converted to psychosis. Dysconnectivity correlated with symptom severity, supporting the idea that thalamic connectivity may have prognostic implications for risk of conversion to full-blown illness.

Brain-Wide Analysis of Functional Connectivity in First-Episode and Chronic Stages of Schizophrenia

“…51 In our dataset, however, we did not find prominent thalamic functional connectivity differences from controls in FE schizophrenic patients or high-risk subjects. This seeming discrepancy may be due to the different methodology we adopted.…”

Sleep Spindle Deficit in Schizophrenia: Contextualization of Recent Findings

“…Impaired spindling in SCZ is in line with in vivo and postmortem findings on volumetric reductions of the thalamus in affected individuals [99][100][101] and with morphofunctional evidence of disrupted thalamocortical connectivity in large first-episode and high-risk samples [102]. None of the clinical conditions associated with impaired spindling activity reviewed here have a typical age of onset in young adulthood nor overlapping clinical symptoms.…”

Altered intrinsic functional brain architecture in female patients with bulimia nervosa

“…In addition, the disorder specificity of our findings remains to be clarified, given that the dysfunctions in some of the regions, such as the striatum, thalamus and OFC, have also been detected in patients with a range of other mental disorders. [59][60][61][62] Finally, as this is, to our knowledge, the first study of topological organization of bulimia nervosa and as so far only a few resting-state fMRI studies have been conducted in patients with this disorder, the results and their interpretation are still tentative. A combined design of resting-state and task-based paradigms would be helpful for strengthening the understanding of the behavioural implications of our findings.…”