Treatment-Resistant Schizophrenia, Clozapine Resistance, Genetic Associations, and Implications for Precision Psychiatry: A Scoping Review

Lights and shadows of clozapine on the immune system in schizophrenia: a narrative literature review

Schizophrenia is a chronic mental disorder and one of the main causes of disability in the world. Approximately 1% of the general population suffers from this disorder, and almost 30% of cases are unresponsive to antipsychotic therapies. Clozapine is a Food and Drug Administration (FDA)-approved antipsychotic drug for treatment-resistant schizophrenia (TRS). Clozapine is also approved for the prevention of suicide associated with schizophrenia. However, clozapine is not the preferred first-line medication because of its potential AEs, including agranulocytosis, metabolic syndromes, and myocarditis. Clozapine prescription requires weekly absolute neutrophil count (ANC) monitoring for the first six months, followed by biweekly monitoring until the patient has finished one year of treatment. Several psychiatric disorders have been reported to be associated with inflammatory biomarkers. Dysregulation of the immune system and the elevation of pro-inflammatory cytokines were also reported to be associated with schizophrenia, highlighting the necessity of further research into the etiology of the disease and the relationship between the immune system and clozapine-responsiveness to support better management of symptoms and potential AEs. In this framework, we searched PubMed using the medical subject headings (MeSH) terms "clozapine", "antipsychotics", "schizophrenia", "treatment-resistant schizophrenia", "immune system", "inflammation", "neuroinflammation", "biomarker", "cytokine", and "chemokine" with the aim of overview the impact of clozapine on the immune system in individuals with treatment-responsive and treatment-resistant schizophrenia.

Network analysis of clinical features in patients with treatment-resistant schizophrenia

Objective

This study compares the clinical features of Treatment-Resistant Schizophrenia (TRS) and Non-Treatment-Resistant Schizophrenia (NTRS) using network analysis.

Methods

We recruited 511 patients, dividing them into TRS (N = 269) and NTRS (N = 242) groups. Eight scales were used: Positive and Negative Syndrome Scale (PANSS), Positive Symptom Assessment Scale (SAPS), Scale for Assessment of Negative Symptoms (SANS), Simpson-Angus Scale (SAS), Abnormal Involuntary Movements Scale (AIMS), Barnes Akathisia Rating Scale (BARS), Calgary Schizophrenia Depression Scale (CDSS), and Global Assessment of Functioning Scale (GAF). Demographic and clinical data were analyzed using T-tests and Chi-square tests. Network analysis was then applied to compare clinical features.

Results

Significant differences were found in the overall architectures (S = 1.396, p < 0.002) and edge weights (M = 0.289, p < 0.009) of TRS and NTRS networks. Nine edges (p < 0.05) and five nodes (p < 0.01) differed, indicating a correlation between clinical symptoms of the two groups. TRS core symptoms were linked to social functions through both positive (SAPS) and negative symptoms (SANS), while NTRS core symptoms were related to general psychopathological symptoms (PANSS-G).

Conclusion

For TRS, it is essential to address both negative and positive symptoms, focusing on the impact of negative symptoms on functioning. Additionally, managing medication side effects is crucial to avoid worsening negative symptoms.

The effect of clozapine on immune-related biomarkers in schizophrenia patients

Globally, schizophrenia is one of the main causes of disability. Approximately 1 % of the general population suffers from schizophrenia, and 30 % of cases are unresponsive to therapy. Clozapine is the gold standard for therapy-resistant schizophrenia (TRS), yet it has limited effectiveness and serious adverse events in some patients. Because of the possibility of severe neutropenia, clozapine administration requires monthly hematological monitoring in the first four months. Previous investigations have demonstrated the immune system alteration after clozapine treatment in schizophrenia patients. Besides, it has been proposed that clozapine changes the cytokines profile in schizophrenia patients. These findings highlighted the need to learn more about the disease's etiology and investigate the relationship between peripheral immune system markers and clozapine response to support strategies for better treatment outcomes. The time decision-making to start clozapine could be significantly decreased if some biomarkers were developed to assist physicians in anticipating whether a particular patient will respond to the medication. Therefore, this study aimed to comprehensively review the effect of clozapine on immune-related biomarkers in schizophrenia patients.

Overcoming the barriers to identifying and managing treatment-resistant schizophrenia and to improving access to clozapine: A narrative review and recommendation for clinical practice

Clozapine is the only approved antipsychotic for treatment-resistant schizophrenia (TRS). Although a large body of evidence supports its efficacy and favorable risk-benefit ratio in individuals who have failed two or more antipsychotics, clozapine remains underused. However, variations in clozapine utilization across geographic and clinical settings suggest that it could be possible to improve its use. In this narrative review and expert opinion, we summarized information available in the literature on the mechanisms of action, effectiveness, and potential adverse events of clozapine. We identified barriers leading to discouragement in clozapine prescription internationally, and we proposed practical solutions to overcome each barrier. One of the main obstacles identified to the use of clozapine is the lack of appropriate training for physicians: we highlighted the need to develop specific professional programs to train clinicians, both practicing and in residency, on the relevance and efficacy of clozapine in TRS treatment, initiation, maintenance, and management of potential adverse events. This approach would facilitate physicians to identify eligible patients and offer clozapine as a treatment option in the early stage of the disease. We also noted that increasing awareness of the benefits of clozapine among healthcare professionals, people with TRS, and their caregivers can help promote the use of clozapine. Educational material, such as leaflets or videos, could be developed and distributed to achieve this goal. The information provided in this article may be useful to improve disease burden and support healthcare professionals, patients, and caregivers navigating the complex pathways to TRS management.

A lifetime of mental health treatments for people with schizophrenia: update and narrative review

PURPOSE OF REVIEW

To provide a summary of the most up-to-date thoughts about treatment for schizophrenia at different stages of illness.

RECENT FINDINGS

The use of Coordinated Specialty Care clinics has arisen as the standard for early on in the treatment of psychosis, providing the notion that recovery is possible. New medications that do not depend on postsynaptic dopamine receptor blockade are soon becoming available.

SUMMARY

A focus should be made by clinicians to personalize treatment plans for each patient who has the possibility of being diagnosed with a primary psychosis and the plan should be to predict outcomes based on biological markers that include genetic vulnerability, early psychosocial combined with pharmacological treatments as needed and then a plan to determine or maintain treatments going forward into the future. It is important to individualize treatment by stage of illness, as well as characteristics of the individual patient. Research is ongoing to advance knowledge for interventions at each stage from the premorbid period through to chronicity.