Psychiatric Genetics Begins to Find Its Footing

Proposal for a Mechanistic Disease Conceptualization in Clinical Neurosciences: The Neural Network Components (NNC) Model

ABSTRACT

Clinical neurosciences, and psychiatry specifically, have been challenged by the lack of a comprehensive and practical framework that explains the core mechanistic processes of variable psychiatric presentations. Current conceptualization and classification of psychiatric presentations are primarily centered on a non-biologically based clinical descriptive approach. Despite various attempts, advances in neuroscience research have not led to an improved conceptualization or mechanistic classification of psychiatric disorders. This perspective article proposes a new-work-in-progress-framework for conceptualizing psychiatric presentations based on neural network components (NNC). This framework could guide the development of mechanistic disease classification, improve understanding of underpinning pathology, and provide specific intervention targets. This model also has the potential to dissolve artificial barriers between the fields of psychiatry and neurology.

Systematic exploration of a decade of publications on psychiatric genetics in Latin America

Psychiatric disorders have a great impact in terms of mortality, morbidity, and disability across the lifespan. Considerable effort has been devoted to understanding their complex and heterogeneous genetic architecture, including diverse ancestry populations. Our aim was to review the psychiatric genetics research published with Latin American populations from 2010 to 2019, and classify it according to country of origin, type of analysis, source of funding, and other variables. We found that most publications came from Brazil, Mexico, and Colombia. Also, local funds are generally not large enough for genome-wide studies in Latin America, with the exception of Brazil and Mexico; larger studies are often done in collaboration with international partners, mostly funded by US agencies. In most of the larger studies, the participants are individuals of Latin American ancestry living in the United States, which limits the potential for exploring the complex gene-environment interaction. Family studies, traditionally strong in Latin America, represent about 30% of the total research publications. Scarce local resources for research in Latin America have probably been an important limitation for conducting bigger and more complex studies, contributing to the reduced representation of these populations in global psychiatric genetics studies. Increasing diversity must be a goal to improve generalizability and applicability in clinical settings.

Use of big data and machine learning algorithms to extract possible treatment targets in neurodevelopmental disorders

Neurodevelopmental disorders (NDDs) impact multiple aspects of an individual's functioning, including social interactions, communication, and behaviors. The underlying biological mechanisms of NDDs are not yet fully understood, and pharmacological treatments have been limited in their effectiveness, in part due to the complex nature of these disorders and the heterogeneity of symptoms across individuals. Identifying genetic loci associated with NDDs can help in understanding biological mechanisms and potentially lead to the development of new treatments. However, the polygenic nature of these complex disorders has made identifying new treatment targets from genome-wide association studies (GWAS) challenging. Recent advances in the fields of big data and high-throughput tools have provided radically new insights into the underlying biological mechanism of NDDs. This paper reviews various big data approaches, including classical and more recent techniques like deep learning, which can identify potential treatment targets from GWAS and other omics data, with a particular emphasis on NDDs. We also emphasize the increasing importance of explainable and causal machine learning (ML) methods that can aid in identifying genes, molecular pathways, and more complex biological processes that may be future targets of intervention in these disorders. We conclude that these new developments in genetics and ML hold promise for advancing our understanding of NDDs and identifying novel treatment targets.

Genetic testing for psychiatric illness in children: ethical issues

PURPOSE OF REVIEW

Genetic and genomic technologies are showing great potential in the field of psychiatry. Genetic testing for psychiatric conditions poses a range of ethical challenges, many of which are likely to be exacerbated for paediatric populations. As a large proportion of psychiatric conditions present in late adolescence and early adulthood, testing in childhood may be considered in some circumstances. Synthesis of issues specific to psychiatric genetic testing in paediatric populations has been limited.

RECENT FINDINGS

Balancing the autonomy of the child and parents requires consideration and judging capacity may be complicated by the presence of psychiatric illness in the child and their family. Health professionals' limited understanding of psychiatric genetics may inhibit delivery of effective psychiatric care. Risk of stigma and discrimination associated with genetic diagnosis and psychiatric illness is compounded for children, who inherently cannot make their own decisions and for whom the impact of a genetic diagnosis is likely to be longest lasting.

SUMMARY

Although the current evidence base suggests genetic testing may not be appropriate for clinical use in psychiatric populations right now, when it is, appropriate pre-test counselling and informed decision making will be essential to support and protect children's developing and future autonomy.

Psychological and physical wellbeing in adults who grew up with a mentally ill parent: A systematic mixed-studies review

OBJECTIVE

Genetic vulnerability factors and adverse childhood experiences (ACE) are associated with an increased risk of psychopathology and other adverse health outcomes across the lifespan. However, less is known about how childhood experiences of parental mental illness affect psychological and physical wellbeing in adulthood. This review synthesizes research on the consequences of growing up as a child of a parent with mental illness (COPMI) for adult psychological and physical wellbeing.

METHODS

A systematic review was conducted following PRISMA guidelines using a mixed-method-studies approach to enable evaluation of the broad array of research designs (Prospero registration #CRD42020221983).

RESULTS

Qualitative studies (k = 10; N = 361) revealed that a COPMI background is associated with substantial psychological challenges in adulthood. Quantitative studies (k = 21; N = 865.402) suggested that COPMI are at increased risk of adult psychopathology, including anxiety and depressive disorders, suicidality, somatoform disorders, substance abuse, but also general medical morbidity and mortality.

CONCLUSIONS

Growing up with a mentally ill parent is associated with adverse psychological and physical outcomes in adulthood, but the evidence-base is limited. Longitudinal studies are needed that go beyond establishing genetic and environmental risk factors to further evaluate how a COPMI background influences wellbeing in adulthood and which targeted clinical interventions could be developed.

Using genetic designs to identify likely causal environmental contributions to psychopathology

The multifactorial nature of psychopathology, whereby both genetic and environmental factors contribute risk, has long been established. In this paper, we provide an update on genetically informative designs that are utilized to disentangle genetic and environmental contributions to psychopathology. We provide a brief reminder of quantitative behavioral genetic research designs that have been used to identify potentially causal environmental processes, accounting for genetic contributions. We also provide an overview of recent molecular genetic approaches that utilize genome-wide association study data which are increasingly being applied to questions relevant to psychopathology research. While genetically informative designs typically have been applied to investigate the origins of psychopathology, we highlight how these approaches can also be used to elucidate potential causal environmental processes that contribute to developmental course and outcomes. We highlight the need to use genetically sensitive designs that align with intervention and prevention science efforts, by considering strengths-based environments to investigate how positive environments can mitigate risk and promote children's strengths.

Rhythm and timing as vulnerabilities in neurodevelopmental disorders

Millions of children are impacted by neurodevelopmental disorders (NDDs), which unfold early in life, have varying genetic etiologies and can involve a variety of specific or generalized impairments in social, cognitive and motor functioning requiring potentially lifelong specialized supports. While specific disorders vary in their domain of primary deficit (e.g. autism spectrum disorder (social), attention-deficit/hyperactivity disorder (attention), developmental coordination disorder (motor) and developmental language disorder (language)), comorbidities between NDDs are common. Intriguingly, many NDDs are associated with difficulties in skills related to rhythm, timing and synchrony though specific profiles of rhythm/timing impairments vary across disorders. Impairments in rhythm/timing may instantiate vulnerabilities for a variety of NDDs and may contribute to both the primary symptoms of each disorder as well as the high levels of comorbidities across disorders. Drawing upon genetic, neural, behavioural and interpersonal constructs across disorders, we consider how disrupted rhythm and timing skills early in life may contribute to atypical developmental cascades that involve overlapping symptoms within the context of a disorder's primary deficits. Consideration of the developmental context, as well as common and unique aspects of the phenotypes of different NDDs, will inform experimental designs to test this hypothesis including via potential mechanistic intervention approaches. This article is part of the theme issue 'Synchrony and rhythm interaction: from the brain to behavioural ecology'.

Genetics of eating disorders in the genome-wide era

Enabled by advances in high throughput genomic sequencing and an unprecedented level of global data sharing, molecular genetic research is beginning to unlock the biological basis of eating disorders. This invited review provides an overview of genetic discoveries in eating disorders in the genome-wide era. To date, five genome-wide association studies on eating disorders have been conducted - all on anorexia nervosa (AN). For AN, several risk loci have been detected, and ~11-17% of the heritability has been accounted for by common genetic variants. There is extensive genetic overlap between AN and psychological traits, especially obsessive-compulsive disorder, and intriguingly, with metabolic phenotypes even after adjusting for body mass index (BMI) risk variants. Furthermore, genetic risk variants predisposing to lower BMI may be causal risk factors for AN. Causal genes and biological pathways of eating disorders have yet to be elucidated and will require greater sample sizes and statistical power, and functional follow-up studies. Several studies are underway to recruit individuals with bulimia nervosa and binge-eating disorder to enable further genome-wide studies. Data collections and research labs focused on the genetics of eating disorders have joined together in a global effort with the Psychiatric Genomics Consortium. Molecular genetics research in the genome-wide era is improving knowledge about the biology behind the established heritability of eating disorders. This has the potential to offer new hope for understanding eating disorder etiology and for overcoming the therapeutic challenges that confront the eating disorder field.

Genome-wide association analyses of post-traumatic stress disorder and its symptom subdomains in the Million Veteran Program

We conducted genome-wide association analyses of over 250,000 participants of European (EUR) and African (AFR) ancestry from the Million Veteran Program using electronic health record-validated post-traumatic stress disorder (PTSD) diagnosis and quantitative symptom phenotypes. Applying genome-wide multiple testing correction, we identified three significant loci in European case-control analyses and 15 loci in quantitative symptom analyses. Genomic structural equation modeling indicated tight coherence of a PTSD symptom factor that shares genetic variance with a distinct internalizing (mood-anxiety-neuroticism) factor. Partitioned heritability indicated enrichment in several cortical and subcortical regions, and imputed genetically regulated gene expression in these regions was used to identify potential drug repositioning candidates. These results validate the biological coherence of the PTSD syndrome, inform its relationship to comorbid anxiety and depressive disorders and provide new considerations for treatment.

Cannabis points to the synaptic pathology of mental disorders: how aberrant synaptic components disrupt the highest psychological functions

Cannabis can elicit an acute psychotic reaction, and its long-term use is a risk factor for schizophrenia. The main active psychoactive ingredient ∆⁹-tetrahydrocannabinol (Δ⁹-THC) activates cannabinoid 1 (CB1) receptors, which are localized to the terminals of glutamate and GABA neurons in the brain. The endogenous cannabinoids are involved in information processing and plasticity at synapses in the hippocampus, basal ganglia, and cerebral cortex. Exogenously applied CB₁ receptor agonists disrupt neuronal dynamics and synaptic plasticity, resulting in cognitive deficits and impairment of the highest psychological functions. Various other pro-psychotic drugs, such as ketamine and methamphetamine, exert their effects in the same microdomain of synaptic spines as Δ⁹-THC. Additionally, many of the most robust findings in psychiatric genetics include components that localize to dendritic spines and have important roles in information processing and plasticity.


Why sleep matters for young people who may get depressed

Depression and anxiety are negative emotional states familiar to us all through personal experience. Less familiar are severe states of depression, in particular, which can actually shorten the lives of sufferers by over a decade. The relationship of these very severe states of illness to the milder cases more common earlier in development is important. Most patients who have suffered from depression will suffer from further episodes during their lifetime, and an early onset may make recurrence more likely. A number of factors increase the risk for depression, including family history, stressful life events, early life experiences, personality (particularly the traits of neuroticism and perfectionism) and mood lability (marked ups and downs). Sleep disturbance may both provoke and/or signal the onset of mood disorder. Sleep is therefore doubly important as a gateway to treatment. Understanding more about how sleep interacts with the established risk factors would allow vulnerable young people to be identified earlier for more effective intervention. Early identification of sleep disorder and depression allows psychological treatments to be used, which are less effective once a full depressive episode and a cascade of neurobiological and psychological effects have occurred.