Mismatch negativity generation in subjects at risk for psychosis: source analysis is more sensitive than surface electrodes in risk prediction

Neighborhood social fragmentation in relation to impaired mismatch negativity among youth at clinical high risk for psychosis and healthy comparisons

Impairments in mismatch negativity (MMN) are well-established in schizophrenia and have been observed in youth at clinical high-risk for psychosis (CHR-P). Prior animal studies have shown that social isolation may be related to neurobiological changes, including reduced MMN-like responses and schizophrenia-like behaviors. In parallel, neighborhood social fragmentation has been shown to be associated with the onset of psychosis. This study investigates the association between neighborhood social fragmentation and MMN impairment among CHR-P youth and healthy comparisons (HC). Data were collected from the North American Prodrome Longitudinal Study Phase 2. Electroencephalography was recorded during an unattended auditory oddball paradigm with duration-, pitch-, and double-deviant tones. Generalized linear mixed models tested the association between neighborhood social fragmentation and the frontal-central averaged MMN for three deviant types for youth at CHR-P and HC separately. The models adjusted for age, sex, race/ethnicity, parental education, parental history of psychosis, and neighborhood poverty. Participants (mean [SD] age: 18.69 [4.59], 41.9% females, 51.3% White non-Hispanic) included 304 CHR-P and 92 HC. In the CHR-P group, greater neighborhood social fragmentation was associated with impaired duration-deviant MMN (bootstrapped β = 0.18, 95% CI: 0.04 to 0.33, p = .022) but not for pitch-deviant (bootstrapped β = 0.09, 95% CI: -0.05 to 0.22, p = .199) or double-deviant MMN (bootstrapped β = 0.10, 95% CI: -0.09 to 0.17, p = .559). Greater neighborhood social fragmentation was associated with impaired duration-deviant MMN amplitude among high-risk individuals. Further research is needed to explore underlying mechanisms.

Abnormal inter-hemispheric effective connectivity from left to right auditory regions during Mismatch Negativity (MMN) tasks in psychosis

Anomalous Mismatch Negativity (MMN) in psychosis could be a consequence of disturbed neural oscillatory activity at sensory/perceptual stages of stimulus processing. This study investigated effective connectivity within and between the auditory regions during auditory odd-ball deviance tasks. The analyses were performed on two magnetoencephalography (MEG) datasets: one on duration MMN in a cohort with various diagnoses within the psychosis spectrum and neurotypical controls, and one on duration and pitch MMN in first-episode psychosis patients and matched neurotypical controls. We applied spectral Granger causality to MEG source-reconstructed signals to compute effective connectivity within and between the left and right auditory regions. Both experiments showed that duration-deviance detection was associated with early increases of effective connectivity in the beta band followed by increases in the alpha and theta bands, with the connectivity strength linked to the laterality of the MMN amplitude. Compared to controls, people with psychosis had overall smaller effective connectivity, particularly from left to right auditory regions, in the pathway where bilateral information converges toward lateralized processing, often rightward. Blunted MMN in psychosis might reflect a deficit in inter-hemispheric communication between auditory regions, highlighting a "dysconnection" already at preattentive stages of stimulus processing as a model system of widespread pathophysiology.

Identify Potential Causal Relationships Between Cortical Thickness, Mismatch Negativity, Neurocognition, and Psychosocial Functioning in Drug-Naïve First-Episode Psychosis Patients

BACKGROUND

Cortical thickness (CT) alterations, mismatch negativity (MMN) reductions, and cognitive deficits are robust findings in first-episode psychosis (FEP). However, most studies focused on medicated patients, leaving gaps in our understanding of the interrelationships between CT, MMN, neurocognition, and psychosocial functioning in unmedicated FEP. This study aimed to employ multiple mediation analysis to investigate potential pathways among these variables in unmedicated drug-naïve FEP.

METHODS

We enrolled 28 drug-naïve FEP and 34 age and sex-matched healthy controls. Clinical symptoms, neurocognition, psychosocial functioning, auditory duration MMN, and T1 structural magnetic resonance imaging data were collected. We measured CT in the superior temporal gyrus (STG), a primary MMN-generating region.

RESULTS

We found a significant negative correlation between MMN amplitude and bilateral CT of STG (CT_STG) in FEP (left: r = -.709, P < .001; right: r = -.612, P = .008). Multiple mediation models revealed that a thinner left STG cortex affected functioning through both direct (24.66%) and indirect effects (75.34%). In contrast, the effects of the right CT_STG on functioning were mainly mediated through MMN and neurocognitive pathways.

CONCLUSIONS

Bilateral CT_STG showed significant association with MMN, and MMN plays a mediating role between CT and cognition. Both MMN alone and its interaction with cognition mediated the effects of structural alterations on psychosocial function. The decline in overall function in FEP may stem from decreased CT_STG, leading to subsequent MMN deficits and neurocognitive dysfunction. These findings underline the crucial role of MMN in elucidating how subtle structural alterations can impact neurocognition and psychosocial function in FEP.