Candidate biomarkers in psychiatric disorders: state of the field

The field of psychiatry is hampered by a lack of robust, reliable and valid biomarkers that can aid in objectively diagnosing patients and providing individualized treatment recommendations. Here we review and critically evaluate the evidence for the most promising biomarkers in the psychiatric neuroscience literature for autism spectrum disorder, schizophrenia, anxiety disorders and post-traumatic stress disorder, major depression and bipolar disorder, and substance use disorders. Candidate biomarkers reviewed include various neuroimaging, genetic, molecular and peripheral assays, for the purposes of determining susceptibility or presence of illness, and predicting treatment response or safety. This review highlights a critical gap in the biomarker validation process. An enormous societal investment over the past 50 years has identified numerous candidate biomarkers. However, to date, the overwhelming majority of these measures have not been proven sufficiently reliable, valid and useful to be adopted clinically. It is time to consider whether strategic investments might break this impasse, focusing on a limited number of promising candidates to advance through a process of definitive testing for a specific indication. Some promising candidates for definitive testing include the N170 signal, an event-related brain potential measured using electroencephalography, for subgroup identification within autism spectrum disorder; striatal resting-state functional magnetic resonance imaging (fMRI) measures, such as the striatal connectivity index (SCI) and the functional striatal abnormalities (FSA) index, for prediction of treatment response in schizophrenia; error-related negativity (ERN), an electrophysiological index, for prediction of first onset of generalized anxiety disorder, and resting-state and structural brain connectomic measures for prediction of treatment response in social anxiety disorder. Alternate forms of classification may be useful for conceptualizing and testing potential biomarkers. Collaborative efforts allowing the inclusion of biosystems beyond genetics and neuroimaging are needed, and online remote acquisition of selected measures in a naturalistic setting using mobile health tools may significantly advance the field. Setting specific benchmarks for well-defined target application, along with development of appropriate funding and partnership mechanisms, would also be crucial. Finally, it should never be forgotten that, for a biomarker to be actionable, it will need to be clinically predictive at the individual level and viable in clinical settings.     

Major depressive disorder: insight into candidate cerebrospinal fluid protein biomarkers from proteomics studies

Introduction: Major Depressive Disorder (MDD) is the leading cause of global disability, and an increasing body of literature suggests different cerebrospinal fluid (CSF) proteins as biomarkers of MDD. The aim of this review is to summarize the suggested CSF biomarkers and to analyze the MDD proteomics studies of CSF and brain tissues for promising biomarker candidates.

Areas covered: The review includes the human studies found by a PubMed search using the following terms: ‘depression cerebrospinal fluid biomarker’, ‘major depression biomarker CSF’, ‘depression CSF biomarker’, ‘proteomics depression’, ‘proteomics biomarkers in depression’, ‘proteomics CSF biomarker in depression’, and ‘major depressive disorder CSF’. The literature analysis highlights promising biomarker candidates and demonstrates conflicting results on others. It reveals 42 differentially regulated proteins in MDD that were identified in more than one proteomics study. It discusses the diagnostic potential of the biomarker candidates and their association with the suggested pathologies.

Expert commentary: One ultimate goal of finding biomarkers for MDD is to improve the diagnostic accuracy to achieve better treatment outcomes; due to the heterogeneous nature of MDD, using bio-signatures could be a good strategy to differentiate MDD from other neuropsychiatric disorders. Notably, further validation studies of the suggested biomarkers are still needed.     

The promise of cognitive behavior therapy for treatment of severe mental disorders: a review of recent developments

Cognitive behavior therapy (CBT), as exemplified by the model of psychotherapy developed and refined over the past 40 years by A.T. Beck and colleagues, is one of the treatments of first choice for ambulatory depressive and anxiety disorders. Over the past several decades, there have been vigorous efforts to adapt CBT for treatment of more severe mental disorders, including schizophrenia and the more chronic and/or treatment refractory mood disorders. These efforts have primarily studied CBT as an adjunctive therapy, i.e., in combination with pharmacotherapy. Given the several limitations of state‐of‐the‐art pharmacotherapies for these severe mental disorders, demonstration of clinically meaningful additive effects for CBT would have important implications for improving public health. This paper reviews the key developments in this important area of therapeutics, providing a summary of the current state of the art and suggesting directions for future research.     

Proteomics studies in inner ear disorders: pathophysiology and biomarkers

Although proteomics has been exploited in a wide range of diseases for identification of biomarkers and pathophysiological mechanisms, there are still biomedical disciplines such as otology where proteomics platforms are underused due to technical challenges and/or complex features of the disease. Thus, in the past few years, healthcare and scientific agencies have advocated the development and adoption of proteomic technologies in otological research. However, few studies have been conducted and limited literature is available in this area. Here, we present the state of the art of proteomics in otology, discussing the substantial evidence from recent experimental models and clinical studies in inner-ear conditions. We also delineate a series of critical issues including minute size of the inner ear, delicacy and poor accessibility of tissue that researchers face while undertaking otology proteomics research. Furthermore, we provide perspective to enhance the impact and lead to the clinical implementation of these proteomics-based strategies.     

Innovative biomarkers in psychiatric disorders: a major clinical challenge in psychiatry

Introduction: Currently, the diagnosis of psychiatric illnesses is based upon DSM-5 criteria. Although endophenotype-specificity for a particular disorder is discussed, the identification of objective biomarkers is ongoing for aiding diagnosis, prognosis, or clinical response to treatment. We need to improve the understanding of the biological abnormalities in psychiatric illnesses across conventional diagnostic boundaries. The present review investigates the innovative post-genomic knowledge used for psychiatric illness diagnostics and treatment response, with a particular focus on proteomics.

Areas covered: This review underlines the contribution that psychiatric innovative biomarkers have reached in relation to diagnosis and theragnosis of psychiatric illnesses. Furthermore, it encompasses a reliable representation of their involvement in disease through proteomics, metabolomics/pharmacometabolomics and lipidomics techniques, including the possible role that gut microbiota and CYP2D6 polimorphisms may play in psychiatric illnesses.

Expert opinion: Etiologic heterogeneity, variable expressivity, and epigenetics may impact clinical manifestations, making it difficult for a single measurement to be pathognomonic for multifaceted psychiatric disorders. Academic, industry, or government’s partnerships may successfully identify and validate new biomarkers so that unfailing clinical tests can be developed. Proteomics, metabolomics, and lipidomics techniques are considered to be helpful tools beyond neuroimaging and neuropsychology for the phenotypic characterization of brain diseases.     

Neuronal nitric oxide synthase (NOS1) and its adaptor,NOS1AP,as a genetic risk factors for psychiatric disorders

Nitric oxide (NO) is a gaseous transmitter produced by nitric oxide synthases (NOSs). The neuronal isoform (NOS‐I, encoded by NOS1) is the main source of NO in the central nervous system (CNS). Animal studies suggest that nitrinergic dysregulation may lead to behavioral abnormalities. Unfortunately, the large number of animal studies is not adequately reflected by publications concerning humans. These include post‐mortem studies, determination of biomarkers, and genetic association studies. Here, we review the evidence for the role of NO in psychiatric disorders by focusing on the human NOS1 gene as well as biomarker studies. Owing to the complex regulation of NOS1 and the varying function of NOS‐I in different brain regions, no simple, unidirectional association is expected. Rather, the ‘where, when and how much’ of NO formation is decisive. Present data, although still preliminary and partially conflicting, suggest that genetically driven reduced NO signaling in the prefrontal cortex is associated with schizophrenia and cognition. Both NOS1 and its interaction partner NOS1AP have a role therein. Also, reduced NOS1 expression in the striatum determined by a length polymorphism in a NOS1 promoter (NOS1 ex1f‐VNTR) goes along with a variety of impulsive behaviors. An association of NOS1 with mood disorders, suggested by animal models, is less clear on the genetic level; however, NO metabolites in blood may serve as biomarkers for major depression and bipolar disorder. As the nitrinergic system comprises a relevant target for pharmacological interventions, further studies are warranted not only to elucidate the pathophysiology of mental disorders, but also to evaluate NO function as a biomarker.     

Prevalence of psychiatric disorders in U.S. older adults: findings from a nationally representative survey

Data on the prevalence of psychiatric disorders in late life are lacking. The present study addresses this gap in the literature by examining the prevalence of the broadest range of psychiatric disorders in late life to date; comparing prevalences across older adult age groups using the largest sample of adults aged 85+; and exploring gender differences in the prevalence of psychiatric disorders in late life. Using data from Wave 2 of the National Epidemiologic Survey on Alcohol and Related Conditions, we examined the prevalence of past-year mood, anxiety, and substance use disorders, and lifetime personality disorders in a nationally representative sample of 12,312 U.S. older adults. We stratified our analyses by gender and by older age groups: young-old (ages 55-64), middle-old (ages 65-74), old-old (ages 75-84), and oldest-old (ages 85+). The proportion of older adults who experienced any past-year anxiety disorder was 11.4%, while the prevalence of any past-year mood disorder was 6.8%. A total of 3.8% of older adults met criteria for any past-year substance use disorder, and 14.5% of older adults had one or more personality disorder. We observed a general pattern of decreasing rates of psychiatric disorders with increasing age. Women experienced higher rates of mood and anxiety disorders, while men had higher rates of substance use disorders and any personality disorder. Gender differences in rates of most psychiatric disorders decreased with increasing age. These data indicate that psychiatric disorders are prevalent among U.S. older adults, and support the importance of prevention, diagnosis, and treatment of psychiatric disorders in this population.     

Rifamycins: an insight into biological activity based on structural investigations

The structures of two compounds of the antibiotic rifamycin series have been studied by X-ray methods: rifamycin B, C₃₉H₄₉NO₁₄, which is active on bacterial RNA polymerase, and rifamycin Y, C₃₉H₄₇NO₁₅, which is devoid of any antibacterial activity. In both cases their p-iodoanilide derivative has been used and the final crystal structure data are now given.A comparative study of the structures of rifamycin B and rifamycin Y, and of the structures of two other ansa-compounds with similar activity on bacterial RNA polymerase, tolypomycin Y and streptovaricin C, together with the analysis of the activity ratios of a series of semisynthetic rifamycins, makes it possible to suggest that the following constitutional and conformational features are common to all the ansa-compounds with anti-bacterial activity: (i) a naphthoquinone or naphthohydroquinone nucleus with free oxygen functions, O(1) and O(2), on C(1) and C(8) respectively: (ii) an amide nitrogen attached to C(2); (iii) a 17-membered chain bridging the chromophoric group; (iv) two free hydroxyl groups attached to atoms C(21) and C(23) of the ansa-bridge and in the same relative positions with respect to each other and with respect to O(1) and O(2). However, the constitution and the conformation of the remaining part of the ansa-bridge can be rather different in different compounds.     

Etiology in psychiatry: embracing the reality of poly‐gene‐environmental causation of mental illness

Intriguing findings on genetic and environmental causation suggest a need to reframe the etiology of mental disorders. Molecular genetics shows that thousands of common and rare genetic variants contribute to mental illness. Epidemiological studies have identified dozens of environmental exposures that are associated with psychopathology. The effect of environment is likely conditional on genetic factors, resulting in gene‐environment interactions. The impact of environmental factors also depends on previous exposures, resulting in environment‐environment interactions. Most known genetic and environmental factors are shared across multiple mental disorders. Schizophrenia, bipolar disorder and major depressive disorder, in particular, are closely causally linked. Synthesis of findings from twin studies, molecular genetics and epidemiological research suggests that joint consideration of multiple genetic and environmental factors has much greater explanatory power than separate studies of genetic or environmental causation. Multi‐factorial gene‐environment interactions are likely to be a generic mechanism involved in the majority of cases of mental illness, which is only partially tapped by existing gene‐environment studies. Future research may cut across psychiatric disorders and address poly‐causation by considering multiple genetic and environmental measures across the life course with a specific focus on the first two decades of life. Integrative analyses of poly‐causation including gene‐environment and environment‐environment interactions can realize the potential for discovering causal types and mechanisms that are likely to generate new preventive and therapeutic tools.     

Response to stress in biological disorders: Implications of stress granule assembly and function

It is indispensable for cells to adapt and respond to environmental stresses, in order for organisms to survive. Stress granules (SGs) are condensed membrane‐less organelles dynamically formed in the cytoplasm of eukaryotes cells to cope with diverse intracellular or extracellular stress factors, with features of liquid‐liquid phase separation. They are composed of multiple constituents, including translationally stalled mRNAs, translation initiation factors, RNA‐binding proteins and also non‐RNA‐binding proteins. SG formation is triggered by stress stimuli, viral infection and signal transduction, while aberrant assembly of SGs may contribute to tissue degenerative diseases. Recently, a growing body of evidence has emerged on SG response mechanisms for cells facing high temperatures, oxidative stress and osmotic stress. In this review, we aim to summarize factors affecting SGs assembly, present the impact of SGs on germ cell development and other biological processes. We particularly emphasize the significance of recently reported RNA modifications in SG stress responses. In parallel, we also review all current perspectives on the roles of SGs in male germ cells, with a particular focus on the dynamics of SG assembly.     

Role of proteomics in biomarker discovery and psychiatric disorders: current status,potentials, limitations and future challenges

Proteomic approaches have advanced clinical research towards more reliable, sensitive and specific biological diagnostic markers for diseases. Mood disorders are most difficult to diagnose and very much prevalent in society; hence, their proper diagnosis becomes essential. Despite tremendous research efforts to dissect the neurobiological basis of psychiatric disorders, the diagnosis and evaluation for such diseases is still poor. Biomarker discovery in psychiatry research has been accelerated by proteomic technologies, accepting the challenges in order to meet disease state-related investigations. Proteomics-based research for disease-specific protein signatures is expected to give a new direction in psychiatry research. Therefore, this may become a more powerful tool to predict the development, course and outcome of the disease towards personalized psychiatric ailments. The review discusses the role of proteomics in elucidating mechanisms of psychiatric disorders, current status, prospects, limitations and new possibilities towards a strong diagnostic tool in the clinical laboratory.     

Proteomics approaches in cervical cancer: focus on the discovery of biomarkers for diagnosis and drug treatment monitoring

Introduction: The HPV virus accounts for the majority of cervical cancer cases. Although a diagnostic tool (Pap Test) is widely available, cervical cancer incidence still remains high worldwide, and especially in developing countries, attributed to a large extent to suboptimal sensitivities of the Pap test and unavailability of the test in developing countries.

Areas covered: Proteomics approaches have been used in order to understand the HPV virus correlation to cervical cancer pathology, as well as to discover putative biomarkers for early cervical cancer diagnosis and drug mode of action.

Expert commentary: The present review summarizes the latest in vitro and in vivo proteomic studies for the discovery of putative cervical cancer biomarkers and the evaluation of available drugs and treatments.     

Transdiagnostic risk of mental disorders in offspring of affected parents: a meta-analysis of family high-risk and registry studies

The offspring of parents with mental disorders are at increased risk for developing mental disorders themselves. The risk to offspring may extend transdiagnostically to disorders other than those present in the parents. The literature on this topic is vast but mixed. To inform targeted prevention and genetic counseling, we performed a comprehensive, PRISMA 2020-compliant meta-analysis. We systematically searched the literature published up to September 2022 to retrieve original family high-risk and registry studies reporting on the risk of mental disorders in offspring of parents with any type of mental disorder. We performed random-effects meta-analyses of the relative risk (risk ratio, RR) and absolute risk (lifetime, up to the age at assessment) of mental disorders, defined according to the ICD or DSM. Cumulative incidence by offspring age was determined using meta-analytic Kaplan-Meier curves. We measured heterogeneity with the I² statistic, and risk of bias with the Quality In Prognosis Studies (QUIPS) tool. Sensitivity analyses addressed the impact of study design (family high-risk vs. registry) and specific vs. transdiagnostic risks. Transdiagnosticity was appraised with the TRANSD criteria. We identified 211 independent studies that reported data on 3,172,115 offspring of parents with psychotic, bipolar, depressive, disruptive, attention-deficit/hyperactivity, anxiety, substance use, eating, obsessive-compulsive, and borderline personality disorders, and 20,428,575 control offspring. The RR and lifetime risk of developing any mental disorder were 3.0 and 55% in offspring of parents with anxiety disorders; 2.6 and 17% in offspring of those with psychosis; 2.1 and 55% in offspring of those with bipolar disorder; 1.9 and 51% in offspring of those with depressive disorders; and 1.5 and 38% in offspring of those with substance use disorders. The offspring's RR and lifetime risk of developing the same mental disorder diagnosed in their parent were 8.4 and 32% for attention-deficit/hyperactivity disorder; 5.8 and 8% for psychosis; 5.1 and 5% for bipolar disorder; 2.8 and 9% for substance use disorders; 2.3 and 14% for depressive disorders; 2.3 and 1% for eating disorders; and 2.2 and 31% for anxiety disorders. There were 37 significant transdiagnostic associations between parental mental disorders and the RR of developing a different mental disorder in the offspring. In offspring of parents with psychosis, bipolar and depressive disorder, the risk of the same disorder onset emerged at 16, 5 and 6 years, and cumulated to 3%, 19% and 24% by age 18; and to 8%, 36% and 46% by age 28. Heterogeneity ranged from 0 to 0.98, and 96% of studies were at high risk of bias. Sensitivity analyses restricted to prospective family high-risk studies confirmed the pattern of findings with similar RR, but with greater absolute risks compared to analyses of all study types. This study demonstrates at a global, meta-analytic level that offspring of affected parents have strongly elevated RR and lifetime risk of developing any mental disorder as well as the same mental disorder diagnosed in the parent. The transdiagnostic risks suggest that offspring of parents with a range of mental disorders should be considered as candidates for targeted primary prevention.     

Risk of metabolic syndrome and its components in people with schizophrenia and related psychotic disorders,bipolar disorder and major depressive disorder: a systematic review and meta‐analysis

Metabolic syndrome (MetS) and its components are highly predictive of cardiovascular diseases. The primary aim of this systematic review and meta‐analysis was to assess the prevalence of MetS and its components in people with schizophrenia and related psychotic disorders, bipolar disorder and major depressive disorder, comparing subjects with different disorders and taking into account demographic variables and psychotropic medication use. The secondary aim was to compare the MetS prevalence in persons with any of the selected disorders versus matched general population controls. The pooled MetS prevalence in people with severe mental illness was 32.6% (95% CI: 30.8%‐34.4%; N = 198; n = 52,678). Relative risk meta‐analyses established that there was no significant difference in MetS prevalence in studies directly comparing schizophrenia versus bipolar disorder, and in those directly comparing bipolar disorder versus major depressive disorder. Only two studies directly compared people with schizophrenia and major depressive disorder, precluding meta‐analytic calculations. Older age and a higher body mass index were significant moderators in the final demographic regression model (z = ?3.6, p = 0.0003, r² = 0.19). People treated with all individual antipsychotic medications had a significantly (p<0.001) higher MetS risk compared to antipsychotic‐naïve participants. MetS risk was significantly higher with clozapine and olanzapine (except vs. clozapine) than other antipsychotics, and significantly lower with aripiprazole than other antipsychotics (except vs. amisulpride). Compared with matched general population controls, people with severe mental illness had a significantly increased risk for MetS (RR = 1.58; 95% CI: 1.35‐1.86; p<0.001) and all its components, except for hypertension (p = 0.07). These data suggest that the risk for MetS is similarly elevated in the diagnostic subgroups of severe mental illness. Routine screening and multidisciplinary management of medical and behavioral conditions is needed in these patients. Risks of individual antipsychotics should be considered when making treatment choices.     

Therapist-supported Internet-based cognitive behaviour therapy yields similar effects as face-to-face therapy for psychiatric and somatic disorders: an updated systematic review and meta-analysis

Providing therapist-guided cognitive behaviour therapy via the Internet (ICBT) has advantages, but a central research question is to what extent similar clinical effects can be obtained as with gold-standard face-to-face cognitive behaviour therapy (CBT). In a previous meta-analysis published in this journal, which was updated in 2018, we found evidence that the pooled effects for the two formats were equivalent in the treatment of psychiatric and somatic disorders, but the number of published randomized trials was relatively low (n=20). As this is a field that moves rapidly, the aim of the current study was to conduct an update of our systematic review and meta-analysis of the clinical effects of ICBT vs. face-to-face CBT for psychiatric and somatic disorders in adults. We searched the PubMed database for relevant studies published from 2016 to 2022. The main inclusion criteria were that studies had to compare ICBT to face-to-face CBT using a randomized controlled design and targeting adult populations. Quality assessment was made using the Cochrane risk of bias criteria (Version 1), and the main outcome estimate was the pooled standardized effect size (Hedges’ g) using a random effects model. We screened 5,601 records and included 11 new randomized trials, adding them to the 20 previously identified ones (total n=31). Sixteen different clinical conditions were targeted in the included studies. Half of the trials were in the fields of depression/depressive symptoms or some form of anxiety disorder. The pooled effect size across all disorders was g=0.02 (95% CI: –0.09 to 0.14) and the quality of the included studies was acceptable. This meta-analysis further supports the notion that therapist-supported ICBT yields similar effects as face-to-face CBT.     

A meta‐review of “lifestyle psychiatry”: the role of exercise,smoking, diet and sleep in the prevention and treatment of mental disorders

There is increasing academic and clinical interest in how “lifestyle factors” traditionally associated with physical health may also relate to mental health and psychological well‐being. In response, international and national health bodies are producing guidelines to address health behaviors in the prevention and treatment of mental illness. However, the current evidence for the causal role of lifestyle factors in the onset and prognosis of mental disorders is unclear. We performed a systematic meta‐review of the top‐tier evidence examining how physical activity, sleep, dietary patterns and tobacco smoking impact on the risk and treatment outcomes across a range of mental disorders. Results from 29 meta‐analyses of prospective/cohort studies, 12 Mendelian randomization studies, two meta‐reviews, and two meta‐analyses of randomized controlled trials were synthesized to generate overviews of the evidence for targeting each of the specific lifestyle factors in the prevention and treatment of depression, anxiety and stress‐related disorders, schizophrenia, bipolar disorder, and attention‐deficit/hyperactivity disorder. Standout findings include: a) convergent evidence indicating the use of physical activity in primary prevention and clinical treatment across a spectrum of mental disorders; b) emerging evidence implicating tobacco smoking as a causal factor in onset of both common and severe mental illness; c) the need to clearly establish causal relations between dietary patterns and risk of mental illness, and how diet should be best addressed within mental health care; and d) poor sleep as a risk factor for mental illness, although with further research required to understand the complex, bidirectional relations and the benefits of non‐pharmacological sleep‐focused interventions. The potentially shared neurobiological pathways between multiple lifestyle factors and mental health are discussed, along with directions for future research, and recommendations for the implementation of these findings at public health and clinical service levels.     

VEGF: an update on biological and therapeutic aspects

Vascular endothelial growth factor (VEGF) is an endothelial cell-specific mitogen and an angiogenic inducer as well as a mediator of vascular permeability. VEGF is essential for developmental angiogenesis and is also required for female reproductive functions and endochondral bone formation. Substantial evidence also implicates VEGF in tumors and intraocular neovascular syndromes. Currently, several clinical trials are ongoing to test the hypothesis that the inhibition of VEGF activity may be beneficial for these conditions.