The association between migrant status and transition in an ultra-high risk for psychosis population

PURPOSE

Migrant status is one of the most replicated and robust risk factors for developing a psychotic disorder. This study aimed to determine whether migrant status in people identified as Ultra-High Risk for Psychosis (UHR) was associated with risk of transitioning to a full-threshold psychotic disorder.

METHODS

Hazard ratios for the risk of transition were calculated from five large UHR cohorts (n = 2166) and were used to conduct a meta-analysis using the generic inverse-variance method using a random-effects model.

RESULTS

2166 UHR young people, with a mean age of 19.1 years (SD ± 4.5) were included, of whom 221 (10.7%) were first-generation migrants. A total of 357 young people transitioned to psychosis over a median follow-up time of 417 days (I.Q.R.147-756 days), representing 17.0% of the cohort. The risk of transition to a full-threshold disorder was not increased for first-generation migrants, (HR = 1.08, 95% CI 0.62-1.89); however, there was a high level of heterogeneity between studies The hazard ratio for second-generation migrants to transition to a full-threshold psychotic disorder compared to the remainder of the native-born population was 1.03 (95% CI 0.70-1.51).

CONCLUSIONS

This meta-analysis did not find a statistically significant association between migrant status and an increased risk for transition to a full-threshold psychotic disorder; however, several methodological issues could explain this finding. Further research should focus on examining the risk of specific migrant groups and also ensuring that migrant populations are adequately represented within UHR clinics.

Physical health assistance in early recovery of psychosis: Study protocol for a randomized controlled trial

AIM

Young people with psychotic disorders have poorer physical health compared to their healthy peers, a state compounded by the metabolic side-effects of antipsychotic medications. To address this, Orygen Youth Health has introduced physical health services including exercise physiologists and dieticians. These services are typically coordinated by the case manager and doctor. It is not yet known whether a treating team member dedicated to physical health will improve engagement, adherence and outcomes with these services. Hence, the protocol is presented here for a trial to evaluate the effect of including a physical health nurse in the care of young people with first-episode psychosis.

METHODS

This will be a single-blind randomized controlled trial that includes 15- to 24-year-olds with first-episode psychosis who have just commenced (within 30 days) antipsychotic medication. The primary outcome will be the event of clinically significant weight gain (≥7% body weight). Participants will be assigned either a physical health nurse in their treating team (in addition to the case manager and doctor) for a 12-week period, or treatment as usual (case manager and doctor). Research assessments will be conducted at baseline, 12 and 26 weeks. Activity trackers worn by participants for the study's duration will measure sleep and physical activity.

CONCLUSION

The present study will determine whether a physical health nurse will facilitate participants in attending and engaging in physical health interventions and whether this will be associated with physical health improvements or the prevention of worsening physical health.

Attenuation of visual evoked responses to hand and saccade-initiated flashes

Sensory attenuation refers to reduced brain responses to self-initiated sensations relative to those produced by the external world. It is a low-level process that may be linked to higher-level cognitive tasks such as reality monitoring. The phenomenon is often explained by prediction error mechanisms of universal applicability to sensory modality; however, it is most widely reported for auditory stimuli resulting from self-initiated hand movements. The present series of event-related potential (ERP) experiments explored the generalizability of sensory attenuation to the visual domain by exposing participants to flashes initiated by either their own button press or volitional saccade and comparing these conditions to identical, computer-initiated stimuli. The key results showed that the largest reduction of anterior visual N1 amplitude occurred for saccade-initiated flashes, while button press-initiated flashes evoked an intermediary response between the saccade-initiated and externally initiated conditions. This indicates that sensory attenuation occurs for visual stimuli and suggests that the degree of electrophysiological attenuation may relate to the causal likelihood of pairings between the type of motor action and the modality of its sensory response.

Self-initiated actions result in suppressed auditory but amplified visual evoked components in healthy participants

Self-suppression refers to the phenomenon that sensations initiated by our own movements are typically less salient, and elicit an attenuated neural response, compared to sensations resulting from changes in the external world. Evidence for self-suppression is provided by previous ERP studies in the auditory modality, which have found that healthy participants typically exhibit a reduced auditory N1 component when auditory stimuli are self-initiated as opposed to externally initiated. However, the literature investigating self-suppression in the visual modality is sparse, with mixed findings and experimental protocols. An EEG study was conducted to expand our understanding of self-suppression across different sensory modalities. Healthy participants experienced either an auditory (tone) or visual (pattern-reversal) stimulus following a willed button press (self-initiated), a random interval (externally initiated, unpredictable onset), or a visual countdown (externally initiated, predictable onset-to match the intrinsic predictability of self-initiated stimuli), while EEG was continuously recorded. Reduced N1 amplitudes for self- versus externally initiated tones indicated that self-suppression occurred in the auditory domain. In contrast, the visual N145 component was amplified for self- versus externally initiated pattern reversals. Externally initiated conditions did not differ as a function of their predictability. These findings highlight a difference in sensory processing of self-initiated stimuli across modalities, and may have implications for clinical disorders that are ostensibly associated with abnormal self-suppression.

Cortical Suppression to Delayed Self-Initiated Auditory Stimuli in Schizotypy: Neurophysiological Evidence for a Continuum of Psychosis

Schizophrenia patients have been shown to exhibit subnormal levels of electrophysiological suppression to self-initiated, button press elicited sounds. These self-suppression deficits have been shown to improve following the imposition of a subsecond delay between the button press and the evoked sound. The current study aimed to investigate whether nonclinical individuals who scored highly on the personality dimension of schizotypy would exhibit similar patterns of self-suppression abnormalities to those exhibited in schizophrenia. Thirty-nine nonclinical individuals scoring above the median (High Schizotypy) and 41 individuals scoring below the median (Low Schizotypy) on the Schizotypal Personality Questionnaire (SPQ) underwent electroencephalographic recording. The amplitude of the N1-component was calculated while participants (1) listened to tones initiated by a willed button press and played back with varying delay periods between the button press and the tone (Active conditions) and (2) passively listened to a series of tones (Listen condition). N1-suppression was calculated by subtracting the amplitude of the N1-component of the auditory evoked potential in the Active condition from that of the Listen condition, while controlling for the activity evoked by the button press per se. The Low Schizotypy group exhibited significantly higher levels of N1-suppression to undelayed tones compared to the High Schizotypy group. Furthermore, while N1-suppression was found to decrease linearly with increasing delays between the button press and the tone in the Low Schizotypy group, this was not the case in the High Schizotypy group. The findings of this study suggest that nonclinical, highly schizotypal individuals exhibit subnormal levels of N1-suppression to undelayed self-initiated tones and an abnormal pattern of N1-suppression to delayed self-initiated tones. To the extent that these results are similar to those previously reported in patients with schizophrenia, these findings provide support for the existence of a neurophysiological "continuum of psychosis".

Subnormal sensory attenuation to self-generated speech in schizotypy: Electrophysiological evidence for a 'continuum of psychosis'

BACKGROUND

A 'continuum of psychosis' refers to the concept that psychotic-like experiences occur to certain extents in the healthy population and to more severe extents in individuals with psychotic disorders. If this concept is valid, neurophysiological abnormalities exhibited by patients with schizophrenia should also be present, to some degree, in non-clinical individuals who score highly on the personality dimension of schizotypy. Patients with schizophrenia have consistently been shown to exhibit electrophysiological suppression abnormalities to self-generated speech. The present study aimed to investigate whether these electrophysiological suppression abnormalities were also present in non-clinical individuals who scored highly on schizotypy.

METHODS

Thirty-seven non-clinical individuals scoring High (above median) and 37 individuals scoring Low (below median) on the Schizotypal Personality Questionnaire (SPQ; a commonly used schizotypy scale) underwent electroencephalographic (EEG) recording. The amplitude of the N1 component of the auditory-evoked potential was measured while participants (a) vocalized simple syllables (Talk condition), (b) passively listened to a recording of these vocalizations (Listen condition) and (c) listened to a recording of the vocalizations while simultaneously watching a video depicting the sound-wave of the forthcoming vocalizations, allowing them to be temporally predicted (Cued Listen condition).

RESULTS

The Low Schizotypy group exhibited significantly reduced N1-amplitude in the Talk condition relative to both the Listen and Cued Listen conditions; that is, they exhibited significant N1-suppression. The High Schizotypy group exhibited significantly lower levels of N1-suppression compared to the Low Schizotypy group. Furthermore, while the Cued Listen condition induced significantly lower N1-amplitudes compared to the Listen condition in the Low Schizotypy group, this was not the case for the High Schizotypy group.

CONCLUSIONS

The results suggest that non-clinical, highly schizotypal individuals exhibit subnormal levels of N1-suppression to self-generated speech, similar to the N1-suppression abnormalities which have previously been reported in patients with schizophrenia. This finding provides empirical support for the existence of a neurophysiological 'continuum of psychosis'.