Independent support for corticopallidal contributions to schizophrenia-related functional impairment

Aberrant resting-state functional connectivity of the globus pallidus interna in first-episode schizophrenia

BACKGROUND

The striatal-pallidal pathway plays an important role in cognitive control and modulation of behaviors. Globus pallidus interna (GPi), as a primary output structure, is crucial in modulating excitation and inhibition. Studies of GPi in psychiatric illnesses are lacking given the technical challenges of examining this small and functionally diverse subcortical structure.

METHODS

71 medication-naïve first episode schizophrenia (FES) participants and 73 healthy controls (HC) were recruited at the Shanghai Mental Health Center. Clinical symptoms and imaging data were collected at baseline and, in a subset of patients, 8 weeks after initiating treatment. Resting-state functional connectivity of sub-regions of the GP were assessed using a novel mask that combines two atlases to create 8 ROIs in the GP.

RESULTS

Baseline imaging data from 63 FES patients and 55 HC met quality standards and were analyzed. FES patients exhibited less negative connectivity and increased positive connectivity between the right anterior GPi and several cortical and subcortical areas at baseline compared to HC (PFWE < 0.05). Positive functional connectivity between the right anterior GPi and several brain areas, including the right dorsal anterior cingulate gyrus, was associated with severity of positive symptoms (PFWE < 0.05) and predicted treatment response after 8 weeks (n = 28, adjusted R2 = 0.486, p < 0.001).

CONCLUSIONS

Our results implicate striatal-pallidal-thalamic pathways in antipsychotic efficacy. If replicated, these findings may reflect failure of neurodevelopmental processes in adolescence and early adulthood that decrease functional connectivity as an index of failure of the limbic/associative GPi to appropriately inhibit irrelevant signals in psychosis.

Subcortical brain iron deposition in individuals with schizophrenia

Subcortical structures play a critical role the pathophysiology and treatment of schizophrenia (SZ), yet underlying neurophysiological processes, in vivo, remain largely unexplored. Brain tissue iron, which can be measured with magnetic resonance-based methods, is a crucial component of a variety of neuronal functions including neurotransmitter synthesis. Here we used a proxy measure of tissue iron to examine basal ganglia and thalamic structures in an adult cohort of individuals with chronic SZ. A publicly available dataset of 72 individuals with SZ between ages 18 and 65, and a matched sample of 74 healthy control (HC) participants were included. A novel method that calculated the inverse-normalized T2*-weighted contrast (1/nT2*) was used to estimate brain iron within the basal ganglia and thalamus. Between group, age- and sex-related differences in 1/nT2* were examined, in addition to correlations with measures of psychopathology and cognition. Individuals with SZ showed greater 1/nT2* (iron index) compared to HCs in the thalamus (p < 0.01, FWE corrected). Age-related 1/nT2* accumulation was noted in regions of the basal ganglia, coinciding with prior work, and prominent sex-differences were noted in the caudate and thalamus (p < 0.01, FWE corrected). No significant relationship was observed between 1/nT2* and measures of neurocognition or psychopathology. Overall, our findings characterize a non-invasive proxy measure of tissue iron in SZ and highlight thalamic iron accumulation as a potential marker of illness.

Disease-Related Risk Factors for Caregiver Burden among Family Caregivers of Persons with Schizophrenia: A Systematic Review and Meta-Analysis

This study aimed to conduct a quantitative synthesis of the clinical correlates of caregiver burden in schizophrenia studies published in the last two decades. Derived from eight electronic databases, this meta-analytic review revisits 34 English articles published from 2000 to 2020 relevant to family caregiver burden in the schizophrenia field. The Newcastle–Ottawa Scale (NOS) was used to assess study quality. The pooled effect sizes of the selected studies ranged from −0.390 to 0.751. The results indicated a significant association between a heavier burden and disease-related risk factors, including more severe symptoms, greater general psychopathology, greater severity of functional impairment, and longer duration of illness. The results show moderating effects of study characteristics (i.e., study quality, participants, and location) on the correlations between these disease-related risk factors and caregiver burden. This review highlights the roles of study characteristics in affecting the inconsistent results for the effects of disease-related risk factors on caregiver burden in families of patients with schizophrenia. Psychosocial interventions are essential for family caregivers of persons with schizophrenia. Future studies incorporating random samples from both high-income and low-to-middle-income countries will be crucial to understand the effects of cultural contexts on caregiver burden in families of persons with schizophrenia.