Reinventing schizophrenia. Updating the construct

Self-Disorder in Schizophrenia: A Revised View (2. Theoretical Revision-Hyperreflexivity)

A growing body of research supports the role of self-disorders as core phenotypic features of schizophrenia-spectrum conditions. Self-disorders comprise various alterations of conscious experience whose theoretical understanding continues to present a challenge. This is the second of two articles that aim to clarify the nature of self-disorders in schizophrenia by considering the currently most influential, phenomenological model of schizophrenia: the basic-self-disturbance or ipseity-disorder model (IDM). The previous paper (article 1) presented a state-of-the-art overview of this model and critically assessed its descriptive adequacy with respect to the clinical heterogeneity and variability of the alterations in self- and world-awareness characteristic of schizophrenia. This paper (article 2) proposes a theoretical revision by considering how hyperreflexivity might form the crucial common thread or generating factor that unifies the heterogeneous, and sometimes even contradictory features of schizophrenic self-disorders. We outline implications of our revised model (IDMrevised) for explanatory research, therapeutic practice, and our general understanding of the abnormalities in question.

The schizophrenia syndrome, circa 2024: What we know and how that informs its nature

With new data about different aspects of schizophrenia being continually generated, it becomes necessary to periodically revisit exactly what we know. Along with a need to review what we currently know about schizophrenia, there is an equal imperative to evaluate the construct itself. With these objectives, we undertook an iterative, multi-phase process involving fifty international experts in the field, with each step building on learnings from the prior one. This review assembles currently established findings about schizophrenia (construct, etiology, pathophysiology, clinical expression, treatment) and posits what they reveal about its nature. Schizophrenia is a heritable, complex, multi-dimensional syndrome with varying degrees of psychotic, negative, cognitive, mood, and motor manifestations. The illness exhibits a remitting and relapsing course, with varying degrees of recovery among affected individuals with most experiencing significant social and functional impairment. Genetic risk factors likely include thousands of common genetic variants that each have a small impact on an individual's risk and a plethora of rare gene variants that have a larger individual impact on risk. Their biological effects are concentrated in the brain and many of the same variants also increase the risk of other psychiatric disorders such as bipolar disorder, autism, and other neurodevelopmental conditions. Environmental risk factors include but are not limited to urban residence in childhood, migration, older paternal age at birth, cannabis use, childhood trauma, antenatal maternal infection, and perinatal hypoxia. Structural, functional, and neurochemical brain alterations implicate multiple regions and functional circuits. Dopamine D-2 receptor antagonists and partial agonists improve psychotic symptoms and reduce risk of relapse. Certain psychological and psychosocial interventions are beneficial. Early intervention can reduce treatment delay and improve outcomes. Schizophrenia is increasingly considered to be a heterogeneous syndrome and not a singular disease entity. There is no necessary or sufficient etiology, pathology, set of clinical features, or treatment that fully circumscribes this syndrome. A single, common pathophysiological pathway appears unlikely. The boundaries of schizophrenia remain fuzzy, suggesting the absence of a categorical fit and need to reconceptualize it as a broader, multi-dimensional and/or spectrum construct.

Reshaping the diagnostic borders: Historical analysis of the diagnostic changes following the introduction of the schizophrenia concept

BACKGROUND

Although the concept of schizophrenia is still widely presented as having replaced that of dementia praecox, studies have shown that the former was broader than the latter, resulting in a more complex diagnostic redistribution. However, this is poorly documented by quantitative approaches.

AIMS

We sought to test the hypothesis that the use of the concept of schizophrenia had caused a diagnostic redistribution and to quantify it.

METHOD

A retrospective study, based on admission register archives of the Strasbourg University Clinic of Psychiatry was conducted. The frequency of diagnoses given to patients were examined at two key time periods: one before (TP1) and one after (TP2) the introduction of the schizophrenia concept (established between 1926 and 1928). Eight main diagnoses related to schizophrenia were considered.

RESULTS

Patients diagnosed with schizophrenia at TP2 mainly received the diagnoses of dementia praecox but also depression, hebephrenia, manic depressive illness, hysteria, paraphrenia, catatonia and mania at TP1. Dementia praecox and hebephrenia were the most relayed by schizophrenia. Bayesian sensitivity analyses confirmed the robustness of our data against distinct scenarios challenging our hypothesis.

CONCLUSIONS

Our results confirm the broadening of the concept of schizophrenia compared to that of dementia praecox but also qualify the different concepts supposed to have been impacted. They provide unique quantitative data that define the contours of the diagnostic redistribution thus provoked. They also give relevant input in the current context where the need to rethink the DSM/ICD concept of schizophrenia is still debated.

Illness Phase as a Key Assessment and Intervention Window for Psychosis

The phenotype of schizophrenia, regardless of etiology, represents the most studied psychotic disorder with respect to neurobiology and distinct phases of illness. The early phase of illness represents a unique opportunity to provide effective and individualized interventions that can alter illness trajectories. Developmental age and illness stage, including temporal variation in neurobiology, can be targeted to develop phase-specific clinical assessment, biomarkers, and interventions. We review an earlier model whereby an initial glutamate signaling deficit progresses through different phases of allostatic adaptation, moving from potentially reversible functional abnormalities associated with early psychosis and working memory dysfunction, and ending with difficult-to-reverse structural changes after chronic illness. We integrate this model with evidence of dopaminergic abnormalities, including cortical D1 dysfunction, which develop during adolescence. We discuss how this model and a focus on a potential critical window of intervention in the early stages of schizophrenia impact the approach to research design and clinical care. This impact includes stage-specific considerations for symptom assessment as well as genetic, cognitive, and neurophysiological biomarkers. We examine how phase-specific biomarkers of illness phase and brain development can be incorporated into current strategies for large-scale research and clinical programs implementing coordinated specialty care. We highlight working memory and D1 dysfunction as early treatment targets that can substantially affect functional outcome.

Biological hypotheses, risk factors, and biomarkers of schizophrenia

Both the discovery of biomarkers of schizophrenia and the verification of biological hypotheses of schizophrenia are an essential part of the process of understanding the etiology of this mental disorder. Schizophrenia has long been considered a neurodevelopmental disease whose symptoms are caused by impaired synaptic signal transduction and brain neuroplasticity. Both the onset and chronic course of schizophrenia are associated with risk factors-induced disruption of brain function and the establishment of a new homeostatic setpoint characterized by biomarkers. Different risk factors and biomarkers can converge to the same symptoms of schizophrenia, suggesting that the primary cause of the disease can be highly individual. Schizophrenia-related biomarkers include measurable biochemical changes induced by stress (elevated allostatic load), mitochondrial dysfunction, neuroinflammation, oxidative and nitrosative stress, and circadian rhythm disturbances. Here is a summary of selected valid biological hypotheses of schizophrenia formulated based on risk factors and biomarkers, neurodevelopment, neuroplasticity, brain chemistry, and antipsychotic medication. The integrative neurodevelopmental-vulnerability-neurochemical model is based on current knowledge of the neurobiology of the onset and progression of the disease and the effects of antipsychotics and psychotomimetics and reflects the complex and multifactorial nature of schizophrenia.