Cognitive control network connectivity differentially disrupted in treatment resistant schizophrenia

Area of Science:

• Neuroscience
• Psychiatry
• Cognitive Science

Background:

• Antipsychotic treatment resistance is common in schizophrenia, affecting one-third of patients.
• The underlying neurobiological mechanisms of treatment resistance remain largely unknown.

Purpose of the Study:

• To investigate the role of cognitive control and network connectivity in differentiating treatment-resistant from treatment-responsive schizophrenia.
• To explore the relationship between brain connectivity, glutamate levels, and symptom severity in schizophrenia.

Main Methods:

• Used functional magnetic resonance imaging (fMRI) with an emotion-yoked reward learning task.
• Employed Dynamic Causal Modelling (DCM) to assess effective connectivity in cortico-striatal-limbic networks.
• Measured anterior cingulate cortex (ACC) glutamate levels and correlated them with connectivity and symptoms.

Main Results:

• Treatment-resistant patients showed altered within-ACC connectivity, unlike responsive patients who had altered ACC-striatal and ACC-sensory connectivity.
• ACC drive to the striatum positively correlated with symptom severity in resistant patients.
• ACC glutamate levels correlated with ACC control over sensory regions in responsive patients, but not in resistant patients.

Conclusions:

• A central non-dopaminergic impairment affecting cognitive control networks may underlie treatment-resistant schizophrenia.
• Disrupted reward learning in resistant schizophrenia is associated with aberrant glutamate function.
• Findings suggest future therapeutic strategies targeting glutamatergic pathways and earlier use of clozapine.