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Depression, a leading cause of global disability, arises from a multifaceted combination of genetic and environmental components. This study explores the relationship between major depressive disorder (MDD) polygenic scores (PGS), characteristics and symptoms of depression, and community-shared socioeconomic factors derived from postal code data in a cohort of 12,646 individuals from the Australian Genetics of Depression Study (AGDS). Our findings reveal that people living in areas with relatively higher socioeconomic advantages and education/occupation scores are more likely to report experiencing fewer depressive symptoms during their worst depressive period, as well as fewer number of lifetime episodes. Additionally, participants who reported depression onset later in life tend to currently reside in wealthier areas. Interestingly, no significant interaction between genetic and socioeconomic factors was observed, suggesting their independent contribution to depression outcomes. This research underscores the importance of integrating socioeconomic factors into psychiatric evaluation and care, and points to the critical role of public policy in addressing mental health disparities driven by socioeconomic factors. Future research should aim to further elucidate the causal relationships within these associations and explore the potential for integrated genetic and socioeconomic approaches in mental health interventions.
The mobility of a weed species is a strong determinant of the optimal management strategy, including whether area-wide management will be beneficial. In this paper, we examine the mobility and dispersal distances of flaxleaf fleabane [Conyza bonariensis (L.) Cronquist; syn.: Erigeron bonariensis L.], widely regarded as a highly mobile weed. We sampled individual weeds from two regions and sampled the same sites in the following season to conduct parentage analysis and assess intergenerational dispersal distances. We find high values of FIS across populations consistent with mostly self-fertilization, but also relatively high genotypic diversity, suggesting that outcrossing does occur at low rates. We find evidence for long-distance dispersal (more than 350 km) and detect dispersal distances of up to 71 km and 36 km within each of the two regions using parentage analysis. We also find high spatial genetic structure within the Riverina region, with sites in 2021 genetically very similar to sites in 2020, indicating that local dispersal may be a more important driver of population genetics than long-distance dispersal, perhaps due to the high rates of seed production and self-fertilization. Glyphosate resistance was not spatially structured in C. bonariensis in these regions, highlighting the role of movement, and significant proportions of susceptible plants were found in both regions. The high levels of mobility, including over potentially long distances, indicate that the value of control and preventing weed seed set is likely to extend beyond the farm and offer “area-wide” benefit.
There is growing evidence that smoking increases the risk of developing psychiatric disorders, but the underlying mechanisms are largely unknown. We examine brain structure as a potential pathway between smoking and psychiatric disease liability.
Methods
We test associations between smoking (initiation, cigarettes per day, cessation, lifetime use) and depression, bipolar disorder, and schizophrenia, with and without correcting for volume of the amygdala, hippocampus, lateral and medial orbitofrontal cortex, superior frontal context, and cortical thickness and surface area. We use three methods that use summary statistics of genome-wide association studies to investigate genome-wide and local genetic overlap (genomic structural equation modeling, local analysis of (co)variant association), as well as causal associations (Mendelian randomization).
Results
While we find causal effects of smoking on brain volume in different brain areas, and with psychiatric disorders, brain volume did not seem to mediate the effect of smoking on psychiatric disorders.
Conclusions
While these findings are limited by characteristics of the included summary statistics (e.g. sample size), we conclude that brain volume of these areas is unlikely to explain a substantial part of any effect of smoking on psychiatric disorders. Nevertheless, genetic methods are valuable tools for exploring other potential mechanisms, such as brain functional connectivity, foregoing the need to collect all phenotypes in one dataset.
In 1995, Roger Bannister, the first man to break four minutes in the mile, gave new life to an old debate. He argued that Black runners had “certain anatomical advantages” that made them all but unbeatable on the track and the roads. Some condemned his remarks. Bannister had, they said, failed to acknowledge the role of culture. Nature or nurture? commentators asked and asked again. The disagreement between the two sides hid a larger consensus: that the Black athlete constitutes a coherent scientific classification, a classification that, in a society that values the natural above the social sciences (and all sciences above the humanities), enters the collective consciousness in biological form. Chapter 1 tells the longer story of that consensus and how science and science writers used a naturalized male/female binary to naturalize a Black/white racial binary – a rhetorical move that the movement to bar trans athletes from competing in women’s and girls’ divisions has borrowed and reversed.
Mood and anxiety disorders co-occur and share symptoms, treatments and genetic risk, but it is unclear whether combining them into a single phenotype would better capture genetic variation. The contribution of common genetic variation to these disorders has been investigated using a range of measures; however, the differences in their ability to capture variation remain unclear, while the impact of rare variation is mostly unexplored.
Aims
We aimed to explore the contributions of common genetic variation and copy number variations associated with risk of psychiatric morbidity (P-CNVs) to different measures of internalising disorders.
Method
We investigated eight definitions of mood and anxiety disorder, and a combined internalising disorder, derived from self-report questionnaires, diagnostic assessments and electronic healthcare records (EHRs). Association of these definitions with polygenic risk scores (PRSs) of major depressive disorder and anxiety disorder, as well as presence of a P-CNV, was assessed.
Results
The effect sizes of both PRSs and P-CNVs were similar for mood and anxiety disorder. Compared to mood and anxiety disorder, internalising disorder resulted in higher prediction accuracy for PRSs, and increased significance of associations with P-CNVs for most definitions. Comparison across the eight definitions showed that PRSs had higher prediction accuracy and effect sizes for stricter definitions, whereas P-CNVs were more strongly associated with EHR- and self-report-based definitions.
Conclusions
Future studies may benefit from using a combined internalising disorder phenotype, and may need to consider that different phenotype definitions may be more informative depending on whether common or rare variation is studied.
Although financial stressors are implicated as risk factors for suicidal behavior, these associations might be confounded by other factors. Furthermore, a move toward high-risk subgroup definition is necessary. The authors used Swedish national registry data to examine the associations between receipt of social welfare, unemployment benefits, or early retirement (N = 627,745−2,260,753) with suicidal behavior in Cox proportional hazards models. They applied co-relative models to improve causal inference, and examined interactions with aggregate genetic risk for suicidality. All three exposures were associated with elevated suicidal behavior risk. Initial hazard ratios for suicide attempt ranged from 1.37−3.86, were similar for suicide death, and declined after controlling for psychopathology and time elapsed after exposure. Age at registration differentially impacted risk of suicidal behavior. Aggregate genetic liability for suicidality was associated with risk, but its effect was not moderated by financial stress. Financial stressors are associated with suicidal behavior risk even after controlling for psychopathology. Associations are attributable in part to familial confounding, though a potentially causal pathway was observed in most cases. Suicidality risk varied as a function of sex and age at exposure; these findings could be used to identify subgroups at high risk who warrant targeted prevention.
Chapter 11 deals with the timescale of history and human evolution. It offers a complexity approach to the evolution of art that attempts to move beyond simplistic theories of the survival function of art, including the much-debated issue of the function of art in the context of sexual selection. After discussing the basic principles of evolution from a complex systems approach, the chapter outlines different evolutionary scenarios: the survival-enhancing function, on the one hand, and the view of art as an evolutionary by-product, on the other. By showing how both evolution and human activity are entangled, interaction-dominated dynamics, the chapter provides an alternative to simplistic gene-for-art assumptions.
Major depressive disorder (MDD) and coronary heart disease (CHD) can both cause significant morbidity and mortality. The association of MDD and CHD has long been identified, but the mechanisms still require further investigation. Seven mRNA microarray datasets containing samples from patients with MDD and CHD were downloaded from Gene Expression Omnibus. Combined matrixes of MDD and CAD were constructed for subsequent analysis. Differentially expressed genes (DEGs) were identified. Functional enrichment analyses based on shared DEGs were conducted to identify pivotal pathways. A protein-protein network was also applied to further investigate the functional interaction. Results showed that 24 overlapping genes were identified. Enrichment analysis indicated that the shared genes are mainly associated with immune function and ribosome biogenesis. The functional interactions of shared genes were also demonstrated by PPI network analysis. In addition, three hub genes including MMP9, S100A8, and RETN were identified. Our results indicate that MDD and CHD have a genetic association. Genes relevant to immune function, especially IL-17 signalling pathway may be involved in the pathogenesis of MDD and CHD.
Autism spectrum disorder is defined by the presence of sustained problems in areas of social cognition and social understanding alongside repetitive and/or restricted patterns of behaviour. Behavioural presentations and developmental trajectories in autism are highly heterogeneous. For most, characteristics variably continue across the lifespan, and, for many, they overlap with numerous overrepresented comorbid combinations spanning behavioural, psychiatric and somatic domains. The current autism diagnostic systems (DSM-5, ICD-11) reflect this heterogeneity, focusing on discerning different assistance needs and symptom severity combinations. An emerging view on the pluralisation of autism – ‘the autisms’ – based on different severity levels and different developmental trajectories is gaining popularity, bolstered by the introduction of the grouping ‘profound autism’ and observations of non-persistence of autism for some. We advance the case for expanding the definition of the plural autisms based also on the numerous different aetiological routes that can lead to autism. Various genetic conditions, susceptibility to infectious agents, non-infectious environmental exposures and immune-mediated occurrences have all been observed to culminate in a diagnosis of autism. As a triad, aetiology, presentation intensity and developmental trajectory offer new ways to classify the autisms, with potentially important implications for research and practice.
Do we owe anything to our genetic relatives qua genetic relatives? The philosophical literature has primarily addressed this question in the context of procreation. But genetic matching databases raise the question of whether we owe anything to previously unknown genetic relatives. This article argues that influential philosophical arguments regarding moral claims to know one’s genetic origins (sometimes referred to as a ‘right to know’) in the context of gamete donation have implications for a broader set of claims. First, these arguments imply more than a claim to know the identity of a genetic relative; the interests which they invoke can only be satisfied through a relationship. Second, the scope of the claims is broader than tends to be acknowledged: even if procreators have special obligations towards their offspring, these arguments imply that weighty moral claims can be made against other genetic relatives in many different contexts.
The literature on cortical excitability, inhibitory and facilitatory properties of the brain in patients with primary dystonia is not well elucidated. We aimed to study the changes in these neurophysiological parameters in patients with dystonia using transcranial magnetic stimulation (TMS).
Methods:
Patients with primary dystonia of presumed genetic etiology (n = 36) and an equal number of healthy controls (HC) (n = 36) were recruited from May 2021 to September 2022. TMS was done using single and paired pulse paradigms. The left motor cortex was stimulated, and responses were recorded from the contralateral first dorsal interosseus muscle. Resting motor threshold (RMT), central motor conduction time, contralateral silent period (cSP), ipsilateral silent period (iSP), short-interval intracortical inhibition (SICI) and intracortical facilitation (ICF) were recorded. All patients underwent whole exome sequencing.
Results:
The mean age of patients was 36.6 ± 13.5 years. There was a significant reduction of cSP (79.5 ± 33.8 vs 97.5 ± 25.4, p = 0.02) and iSP (42.3 ± 13.5 vs 53.8 ± 20.8, p = 0.003) in patients compared to HC. SICI was significantly enhanced in patients (0.38 ± 0.23) compared to HC (0.51 ± 0.24, p = 0.006). RMT was higher (42.1 ± 7.9 vs 37.1 ± 6.4%, p = 0.032) with enhanced SICI (0.36 ± 0.21 vs 0.56 ± 0.25, p = 0.004) in patients with generalized dystonia (n = 20) compared to HC. The genetically determined subgroup (n = 13) had significantly enhanced SICI compared to HC (0.23 ± 0.15 vs 0.51 ± 0.23, p = 0.001).
Conclusions:
Patients with primary dystonia have altered cortical excitability and inhibition with significantly reduced silent period and enhanced intracortical inhibition suggestive of impaired GABAergic neurotransmission.
Autism spectrum disorder (ASD) is a neurodevelopmental disorder with significant social, communicative, and behavioral challenges, and its prevalence is increasing globally at an alarming rate. Children with ASD often have nutritional imbalances, and multiple micronutrient deficiencies. Among these, zinc (Zn2+) deficiency is prominent and has gained extensive scientific interest over the past few years. Zn2+ supports numerous proteins, including enzymes and transcription factors, and controls neurogenesis and cell differentiation. It modulates synaptic transmission and plasticity by binding to receptors, ion channels, and transporters. These interactions are crucial, as changes in these processes may contribute to cognitive and behavioral abnormalities in neurodevelopmental disorders, including ASD. Notably, mutations in genes linked to ASD result in Zn2+ dyshomeostasis, altering pivotal biological processes. In addition, Zn2+ promotes gut health by maintaining gut wall integrity, preventing inflammation and leaky gut, preventing translocation of gut bacteria and their metabolites into systemic circulation, and supporting cognitive processes via the gut–brain axis. Zn2+ deficiency during pregnancy alters gut microbiota composition, induces pro-inflammatory cytokine production, may affect neuronal functioning, and is associated with ASD etiology in offspring, as well as the exacerbation of autistic traits in genetically predisposed children. This review focuses on Zn2+ dyshomeostasis, discussing various Zn2+-dependent dysfunctions underlying distinct autistic phenotypes and describing recent progress in the neurobiology of individuals with ASD and animal models.
This paper reports the methods and preliminary findings of Germina, an ongoing cohort study to identify biomarkers and trajectories of executive functions and language development in the first 3 years of life. 557 mother-infant dyads (mean age of mothers 33.7 years, 65.2% white, 48.7% male infants) have undergone baseline and are currently collecting data for other timepoints. A linear regression was used to predict baseline Bayley-III using scores derived from data-driven sparse partial least squares utilizing a multiple holdout framework of 15 domains. Significant associations were found between socioeconomic/demographic characteristics (B = 0.29), epigenetics (B = 0.11), EEG theta (B = 0.14) and beta activity (B = 0.11), and microbiome functional pathways (B = 0.08) domains, and infant development measured by the Bayley-III at T1, suggesting potential interventions to prevent impairments.
Low birthweight is a risk factor for type 2 diabetes. We hypothesised that differential associations between birthweight and clinical characteristics in persons with and without type 2 diabetes may provide novel insights into the role of birthweight in type 2 diabetes and its progression. We analysed UK Biobank data from 9,442 persons with and 254,446 without type 2 diabetes. Associations between birthweight, clinical traits, and genetic predisposition were assessed using adjusted linear and logistic regression, comparing the lowest and highest 25% of birthweight to the middle 50%. Each kg increase in birthweight was associated with higher BMI, waist, and hip circumference, with stronger effects in persons with versus without type 2 diabetes (BMI: 0.74 [0.58, 0.90] vs. 0.21 [0.18, 0.24] kg/m2; waist: 2.15 [1.78, 2.52] vs. 1.04 [0.98, 1.09] cm; hip: 1.65 [1.33, 1.97] vs. 1.04 [1.04, 1.09] cm). Family history of diabetes was associated with higher birthweight regardless of diabetes status, albeit with a twofold higher effect estimate in type 2 diabetes. Low birthweight was further associated with prior myocardial infarction regardless of type 2 diabetes status (OR 1.33 [95% CI 1.11, 1.60] for type 2 diabetes; 1.23 [95% CI 1.13, 1.33] without), and hypertension (OR 1.25 [1.23, 1.28] and stroke 1.24 [1.14, 1.34]) only among persons without type 2 diabetes. Differential associations between birthweight and cardiometabolic traits in persons with and without type 2 diabetes illuminate potential causal inferences reflecting the roles of pre- and postnatal environmental versus genetic aetiologies and disease mechanisms.
Richard Tremblay started his professional career as a clinician with juvenile delinquents and mentally ill offenders. He spent the rest of his career doing longitudinal and experimental studies to identify effective preventive interventions during the preschool and elementary school years. Results from these studies showed that early interventions with at risk children and their parents had very long-term impacts. Within these longitudinal studies, he also studied genetic and epigenetic effects on the development of violent behavior.
Tics are brief, sudden, non-rhythmic, repetitive movements. Tics can be motor or vocal. Further, both motor and vocal tics can be either simple or complex. Simple tics typically involve only one group of muscles and are brief and meaningless, whereas complex tics may last longer and appear more purposeful. Tic disorders usually begin in childhood and are classified according to the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) into four groups: (1) provisional tic disorder, (2) chronic motor or vocal tic disorder, (3) Tourette disorder (or Gilles de la Tourette syndrome), (4) tic disorder not otherwise specified. As tics can resemble almost any other movement disorder, phenotypic analysis alone is insufficient and patients must be questioned whether the execution is preceded by a premonitory sensation (urge to do, urge to move) and whether a temporary control of the movement can be achieved. Also, relief following execution of the tic is frequently reported. There are no biomarkers available for tics and diagnosis therefore remains strictly clinical.
Parkinson’s disease has been recently redefined clinically and its underlying molecular biology determined. Although it is a neurodegenerative disease, loss of neurons is largely focal rather than large scale; symptoms are caused more by neurochemical deficits and dysfunctional cells than cell loss. The two main pathologic features are loss of dopamine neurons in the substantia nigra of the midbrain and the more widespread aggregation of a-synuclein in certain vulnerable neurons in the brain. Several triggers can cause the molecular cascade that kills dopamine neurons and makes the a-synuclein protein fibrilize and aggregate initially in brainstem neurons, including genetic variants and post-translational modification of the protein. The disease is slowly progressive with the propagation of aggregates from vulnerable synapses to the entire neuron, then from one neuron to other neurons and glial cells. Different propagation mechanisms have been identified for these different brain cells that work in concert to sustain the slow disease process. Current therapeutic delivery of dopamine or deep brain stimulation temporarily relieve the symptoms with disease-modifying treatments now able to be trialled due to identifying the underlying molecular biology.
"Ataxia" refers to both the neurologic syndrome of motor coordination and to a large and diverse group of diseases that have motor coordination impairment as their main clinical feature. The brain structure most consistently affected is the cerebellum. Although many different brain diseases may manifest with ataxia, the vast majority of slowly progressive ataxias are genetic diseases. Indeed, genetic molecular analysis has become the cornerstone of both diagnosis and classification of this complex group of conditions. In this overview, the basics of the clinical features and the classification of these diseases, as well as common conditions, and recently defined novel forms of ataxia are discussed.