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Despite known deficits in postural control in patients with schizophrenia, this domain has not been investigated in youth at ultra high-risk (UHR) for psychosis. This is particularly relevant as postural control implicates dysfunction in the cerebellum-a region implicated in cognitive dysmetria conceptions of schizophrenia but poorly understood in the prodrome. Here, we extended our understanding of movement abnormalities in UHR individuals to include postural control, and have linked these deficits to both symptom severity and cerebello-cortical network connectivity. UHR and healthy control participants completed an instrumentally based balance task to quantify postural control along with a resting state brain imaging scan to investigate cerebellar networks. We also quantified positive and negative symptom severity with structured clinical interviews. The UHR group showed overall increased postural sway and decreased cerebello-cortical resting state connectivity, relative to controls. The decreased cerebello-cortical connectivity was seen across multiple networks. Postural sway was also correlated with cerebellar connectivity in this population and uniquely positively correlated with the severity of negative symptoms. Finally, symptom severity was also associated with cerebellar connectivity. Together, our results point to a potential deficit in sensory integration as an underlying contributor to the increased postural sway, and provide evidence of cerebellar abnormalities in UHR individuals. These results extend our understanding of the motor abnormalities of UHR individuals beyond striatum-based dyskinesias to include postural control and sensory integration deficits, and implicate the cerebellum as a distinct neural substrate preceding the onset of psychosis. Taken together, our results extend the cognitive dysmetria framework to UHR populations. Hum Brain Mapp 35:4064–4078, 2014. © 2014 Wiley Periodicals, Inc.

Aim Internet use has grown exponentially in the past decade, but there has been little systematic research to inform our understanding of how this phenomenon may relate to mental illness. Although several characteristics of individuals experiencing psychotic-like experiences (PLEs) may render this group particularly susceptible to problematic Internet use, to date there have been no studies examining Internet use in this group. Because the experience of PLEs is considered a risk “behaviour” for formal psychosis, it is crucial to understand how patterns of Internet use may be tied to the progression of illness. Methods A total of 170 young adults were followed for 2 months, and grouped into those showing a steady/improved course of PLEs (PLE-Improved/Constant) and those showing an exacerbation in PLEs (PLE-Increase). Internet addiction and a factor ‘Reality Substitute’ were examined within and between the two groups. Results Findings indicated that although both groups reported a similar level of Internet addiction and Reality Substitute at baseline, the PLE-Improved/Constant group showed longitudinal declines in both domains of problematic Internet usage whereas the PLE-Increase group's reported level remained constant. Further, there were moderate correlations between PLEs and domains of problematic Internet use, and the magnitude of association with Reality Substitute for the PLE-Increase group grew significantly over time. Conclusion Taken together, results implicate a close link between continued problematic Internet use and the phenomena of PLEs.

Objective Growing evidence indicates that non-clinical psychotic-like experiences occur in otherwise healthy individuals, suggesting that psychosis may occur on a continuum. However, little is know about how the diathesis for formal psychosis maps on to individuals at the non-clinical side of this continuum. Our current understanding of the pathophysiology of schizophrenia implicates certain key factors such as early developmental abnormalities and fronto-striatal dysfunction. To date, no studies have examined these core factors in the context of non-clinical psychosis.