Gray Matter Changes in Subjects at High Risk for Developing Psychosis and First-Episode Schizophrenia: A Voxel-Based Structural MRI Study

Abstract Background Clinical high-risk (CHR) for psychosis is indicated by ultra-high risk (UHR) and basic symptom (BS) criteria; however, conversion rates are highest when both UHR and BS criteria are fulfilled (UHR&BS). While BSs are considered the most immediate expression of neurobiological aberrations underlying the development of psychosis, research on neurobiological correlates of BS is scarce. Methods We investigated gray matter volumes (GMV) of 20 regions of interest (ROI) previously associated with UHR criteria in 90 patients from the Bern early detection service: clinical controls (CC), first-episode psychosis (FEP), UHR, BS and UHR&BS. We expected lowest GMV in FEP and UHR&BS, and highest volume in CC with UHR and BS in-between. Results Significantly, lower GMV was detected in FEP and UHR&BS patients relative to CC with no other significant between-group differences. When ROIs were analyzed separately, seven showed a significant group effect (FDR corrected), with five (inferior parietal, medial orbitofrontal, lateral occipital, middle temporal, precuneus) showing significantly lower GM volume in the FEP and/or UHR&BS groups than in the CC group (Bonferroni corrected). In the CHR group, only COGDIS scores correlated negatively with cortical volumes. Conclusions This is the first study to demonstrate that patients who fulfill both UHR and BS criteria – a population that has been associated with higher conversion rates – exhibit more severe GMV reductions relative to those who satisfy BS or UHR criteria alone. This result was mediated by the BS in the UHR&BS group, as only the severity of BS was linked to GMV reductions.

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T39. IMPAIRED SENSORIMOTOR GATING USING THE ACOUSTIC PREPULSE INHIBITION PARADIGM IN INDIVIDUALS AT A CLINICAL HIGH RISK FOR PSYCHOSIS

Schizophrenia Bulletin ◽

10.1093/schbul/sbaa029.599 ◽

2020 ◽

Vol 46 (Supplement_1) ◽

pp. S246-S246

Author(s):

Qijing Bo ◽

Zhen Mao ◽

Qing Tian ◽

Weidi Li ◽

Lei Zhao ◽

...

Keyword(s):

High Risk ◽

Prepulse Inhibition ◽

Clinical Characteristics ◽

Sensorimotor Gating ◽

Spatial Separation ◽

Structured Interview ◽

First Episode ◽

Clinical High Risk ◽

Neurocognitive Functions ◽

First Episode Schizophrenia

Abstract Background Many robust studies on prepulse inhibition (PPI) were conducted in patients with schizophrenia, and, increasingly, evidence has indicated individuals who are at clinical high risk for psychosis (CHR). The specificity of the PPI is insufficient with the classic paradigm. The current study investigated an improved perceived spatial separation PPI (PSSPPI) paradigm in CHR individuals, compared with patients of first-episode schizophrenia (FES) and healthy controls (HC), and the relationship between PPI, demographics, clinical characteristics, and cognitive performance. Methods We included 53 FESs, 55 CHR individuals, and 53 HCs. CHRs were rated on the Structured Interview for Prodromal Syndromes (SIPS). The prepulse inhibition measures of perceived spatial co-location PPI (PSCPPI) and PSSPPI paradigms were applied using 60- and 120-ms lead intervals. The MATRICS Consensus Cognitive Battery (MCCB) was used to assess neurocognitive functions. Results Compared with HC, the CHR group had lower PSSPPI level (ISI=60 ms, P<0.001; ISI=120 ms, P<.001). PSSPPI showed a large effect size (ES) between CHR and HC (ISI=60 ms, ES=0.91; ISI=120 ms, ES=0.98); on PSSPPI using 60-ms lead interval, ES ranged from small to large from CHR to FES. PPI deficits in CHR were unrelated to demographics, clinical characteristics, and cognition. Discussion CHR individuals show a sensorimotor gating deficit similar to FES patients on PSSPPI of the startle response, with greater sensitivity than the classic PPI paradigm. PSSPPI appears a promising objective approach for identifying individuals at clinical high risk for psychosis related to a high risk of transition to schizophrenia.

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