Brave New World: Harnessing the promise of biomarkers to help solve the epigenetic puzzle

A narrative review of nosology and the concept of schizophrenia: criticism and proposal

Schizophrenia diagnostics have evolved to adapt to clinical needs and scientific advances, and the current denominations emerged at the beginning of the twentieth century. Most problems arise while integrating clinical experiences, based on historical psychopathological descriptions, with emerging translational neuroscience research. This study aimed to evaluate the state-of-the-art critics of the current schizophrenia concept and their recommendations for new concepts. We performed a narrative review of the literature and searched for studies published in English in PubMed in the last 2 years which discussed the diagnosis of schizophrenia. Two authors independently selected the studies after analyzing the abstracts. Subsequently, studies were selected for this review by consensus. Twenty-six studies were selected, and all authors, except two, had restrictions on the current categorical model for the diagnosis of schizophrenia owing to the heterogeneity of symptomatology and high frequency of comorbidity. Eight studies proposed changes to the concept of schizophrenia. The central proposition was to adopt psychotic syndrome as a core feature instead of the current concept of schizophrenia. We synthesize these proposals using psychosis as a spectrum that includes schizophrenia as a more severe case at the end of the spectrum.

NRN1 genetic variability and methylation changes as biomarkers for cognitive remediation therapy response in schizophrenia

Cognitive remediation therapy (CRT) demonstrates potential in enhancing cognitive function in schizophrenia (SZ), though the identification of molecular biomarkers remains challenging. The Neuritin-1 gene (NRN1) emerges as a promising candidate gene due to its association with SZ, cognitive performance and response to neurotherapeutic treatments. We aimed to investigate whether NRN1 genetic variability and methylation changes following CRT are related to cognitive improvements. Twenty-five SZ patients were randomly assigned to CRT or treatment-as-usual (TAU) groups, with cognitive function and NRN1 methylation assessed pre- and post-intervention using the MATRICS Consensus Cognitive Battery and EpiTYPER. Besides, eleven NRN1 polymorphisms were genotyped. Methylation changes (Δm = post - pre) were analyzed via sparse Partial Least Square Discriminant Analysis (sPLS-DA) to identify latent components (LCs) distinguishing CRT from TAU. To further explore methylation patterns of these LCs, CpG units were grouped into two subsets, yielding Δm means for those with increased and decreased methylation. Cognitive changes (Δcog = post - pre) were used to identify CRT improvers (CRT-I, Δcog ≥ 1), and the association between methylation changes and cognitive improvements post-therapy was also tested. We identified two LCs that differentiated CRT from TAU with a classification error rate of 0.28. The main component, LC1, included 25 CpG units. The subsets of CpG units with increased and decreased post-therapy methylation differed significantly between the two treatment arms, suggesting that differences were not merely data-driven but reflected meaningful biological variation. Additionally, CpG units linked to therapy were also associated with cognitive improvement, with LC1 and the subset of CpG units showing increased methylation post-therapy distinguishing CRT-I from the rest of the patients across multiple cognitive domains. Furthermore, the effect of LC1 on speed processing improvement after CRT was enhanced by considering the NRN1-rs9405890 polymorphism. Notably, these CpG units, particularly those with increased methylation after CRT, overlapped with key gene regulatory elements. Our model, integrating genetics and epigenetics, boosts the understanding of CRT response variability and highlights this multi-level approach as a promising strategy for identifying potential NRN1-related biomarkers of CRT effects, though further studies with larger samples are needed.

Changes in BDNF methylation patterns after cognitive remediation therapy in schizophrenia: A randomized and controlled trial

Although cognitive remediation therapy (CRT) produces cognitive benefits in schizophrenia, we do not yet understand whether molecular changes are associated with this cognitive improvement. A gene central to synaptic plasticity, the BDNF, has been proposed as one potential route. This study assesses whether BDNF methylation changes following CRT-produced cognitive improvement are detected. A randomized and controlled trial was performed with two groups (CRT, n = 40; TAU: Treatment as Usual, n = 20) on a sample of participants with schizophrenia. CRT was delivered by trained therapists using a web-based computerized program. Mixed Models, where the interaction of treatment (CRT, TAU) by time (T0: 0 weeks, T1: 16 weeks) was the main effect were used. Then, we tested the association between the treatment and methylation changes in three CpG islands of the BDNF gene. CRT group showed significant improvements in some cognitive domains. Between-groups differential changes in 5 CpG units over time were found, 4 in island 1 (CpG1.2, CpG1.7, CpG1.10, CpG1.17) and 1 in island 3 (CpG3.2). CRT group showed increases in methylation in CpG1.2, CpG1.7 and decreases in pG1.10, CpG1.17, and CpG3.2. Differences in the degree of methylation were associated with changes in Speed of Processing, Working Memory, and Verbal Learning within the CRT group. Those findings provide new data on the relationship between cognitive improvement and changes in peripheral methylation levels of BDNF gene, a key factor involved in neuroplasticity regulation. Trial Registration: NCT04278027.

Ethnoracialized group differences in attitudes and knowledge about schizophrenia and willingness to engage in biomarker research: The UBIGR Study

Although there is renewed optimism in biomarker research in schizophrenia, there is also need for greater inclusion of historically underrepresented groups in the research. In the present study, we surveyed 599 African American, 352 American Indian/Alaska Native, and 725 NonHispanic White participants about their attitudes toward research, knowledge and attitudes about schizophrenia, and willingness to engage in biomarker testing. Attitudes toward research were examined using the standardized 7-item Research Attitudes Questionnaire (RAQ) measure. Using structural equation modeling (SEM), we tested our predictive model of the likelihood of willingness to engage in biomarker testing for schizophrenia risk. Members of historically underrepresented groups were less willing to engage in biomarker testing. Overall, attitudes toward research, particularly trust, influenced biomarker testing willingness. These findings suggest that factors influencing willingness to engage in schizophrenia biomarker testing may be modifiable by outreach engagement and education.

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.

Polygenic risk scores cannot make their mark on psychiatry without considering epigenetics

We generally agree with Burt's thesis. However, we note that the author did not discuss epigenetics, the study of how the environment can alter gene structure and function. Given epigenetic mechanisms, the utility of polygenic risk scores (PRS) is limited in studies of development and mental illness. Finally, in this commentary we expand upon the risks of reliance upon PRSs.

Social anhedonia and other indicators of risk for schizophrenia: Theory and inquiry

In this commentary, the author traces theoretical contributions that fueled her interest in the role of social/interpersonal striving, relating, and enjoyment in terms of schizophrenia. Social anhedonia is discussed in the context of schizophrenia. The author reviews selective empirical evidence indicating that social anhedonia has a unique role in terms of risk for schizophrenia as well as schizophrenia outcome. Other risk indicators for adult schizophrenia-spectrum outcomes are briefly considered. The author discusses the measurement of social anhedonia across the lifespan and transdiagnostically. Finally, this commentary offers a critique of current strategies for risk calculation.

Social anhedonia in Malaysian schizophrenia patients and healthy participants

The reduced capacity for social and interpersonal interactions, social anhedonia, is an important aspect of various psychiatric disorders, especially schizophrenia-spectrum disorders. The goal of the present study was to validate a Malay translation of the adult version of the Anticipatory and Consummatory Interpersonal Pleasure Scale (ACIPS; Gooding and Pflum, 2014), a relatively short and easy to administer indirect measure of social anhedonia. This cross-sectional study included 95 (47 male, 48 female) schizophrenia patients and 300 (77 male, 223 female) healthy subjects. Participants were given Malay versions of the ACIPS, Snaith Hamilton Pleasure Scale (SHAPS-M), and Beck Depression Inventory (BDI-M). The ACIPS exhibited good internal consistency (Ordinal alpha = 0.966). Total ACIPS scores were inversely correlated with the BDI-M scores, and positively correlated with total SHAPS-M scores. Factor analysis yielded a three-factor solution which accounted for 52.06% of the variance. As expected, the schizophrenia patients scored significantly lower than the healthy community participants on the ACIPS, t(130) = 4.26, p < 0.001. The Malay translation of the ACIPS showed good concurrent validity and excellent internal consistency. Taken together, these data provide further validation for the utility of the ACIPS in a cross-cultural context.

Genetic variation and susceptibility to schizophrenia: Work in progress

After finishing my pharmacy studies, I became interested in undertaking a PhD in the genetics of psychiatric disorders, specifically, the genetics of schizophrenia. At this time in 1990, only limited information about the human genome was available. Still, the research soon picked up some speed with introduction of the polymerase chain reaction (PCR) into research laboratories and the growing knowledge about the structure of the human genome. In my research, I aim to identify altered genes that increase the susceptibility to schizophrenia. The idea was that identifying these genes allows an understanding of the underlying biochemistry, therefore facilitating the development of targeted pharmacotherapies. While we have come closer to achieving this aim, the complexity of the identified genetic architecture and the phenotypes implies that there is still much research to be completed before we can achieve this aim.

Validation of the Korean Version of the Anticipatory and Consummatory Interpersonal Pleasure Scale in Non-help-seeking Individuals

The Anticipatory and Consummatory Interpersonal Pleasure Scale (ACIPS) is a psychometric instrument that has been used to indirectly measure social anhedonia in many cross-cultural contexts, such as in Western (US), European (French, Spanish), Eastern (Chinese), and Israeli samples. However, little is known about the psychometric properties of the ACIPS in Korean samples. The primary goal of this study was to validate the Korean version of the ACIPS among non-help-seeking individuals. The sample consisted of 307 adult individuals who had no current or prior psychiatric history. Participants were administered the ACIPS, along with the Behavioral Inhibition and Behavioral Activation Scales (BIS/BAS) and Beck Depression Inventory (BDI). We examined the association of the total ACIPS scores with the other measures. The ACIPS showed good internal consistency. We also explored the factor structure of the Korean translation of the ACIPS using principal component analysis with Promax rotation and Kaiser normalization. Factor analysis yielded a three-factor structure that accounted for 58.8% of the variance. The three-factor model included the following subdomains: interactions involving close relationships, casual interactions, and interactions involving family members. Total BAS and BIS scores were significantly associated with total ACIPS scores, while BDI scores were inversely associated with total ACIPS scores. The current research indicates that the Korean version of the ACIPS is a useful and valid scale. Future directions include using the Korean translation of the ACIPS to elucidate the varying degrees of hedonic capacity in psychiatric patients.