Publications by authors named "Dalvie S"

Article Synopsis
  • The study explores the biological differences linked to PTSD by examining DNA methylation changes in blood, suggesting they could indicate susceptibility or effects of trauma.
  • Conducted by the Psychiatric Genomics Consortium, the research included nearly 5,100 participants to identify specific genetic markers associated with PTSD.
  • Results showed 11 significant CpG sites related to PTSD, with some also showing correlations between blood and brain tissue methylation, highlighting their potential role in understanding PTSD biology.
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Objective: The aetiology of epilepsy is known to have genetic contributions, yet results from genome-wide association studies (GWAS) have not always been consistent. We undertook a systematic review in order to identify risk variants for epilepsy.

Methods: This systematic review was conducted in accordance with the PRISMA protocol.

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  • Researchers aimed to create and validate Methylation Risk Scores (MRS) using machine learning to identify individuals at risk for PTSD based on genomic and trauma exposure data.
  • The study developed three models: eMRS (which combines trauma exposure and methylation data), MoRS (which relies only on methylation data), and MoRSAE (which adjusts MoRS for trauma exposure).
  • The eMRS model showed the best performance with a 92% accuracy, and all models were able to predict post-deployment PTSD significantly, suggesting that including trauma exposure improves risk assessment.
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Article Synopsis
  • The study investigates the link between post-traumatic stress disorder (PTSD) and differences in DNA methylation, a type of gene regulation, in blood samples from individuals diagnosed with PTSD compared to trauma-exposed controls.
  • Researchers conducted a large-scale analysis involving over 5,000 participants from various civilian and military studies, using standardized procedures for PTSD assessment and DNA methylation testing.
  • The results revealed 11 specific DNA methylation sites associated with PTSD, and found similarities in methylation patterns between blood and brain tissues, suggesting a biological basis for the condition.
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  • Cognitive impairment significantly impacts functional outcomes in schizophrenia, but the biological causes of this dysfunction are still not fully understood.
  • The study used advanced genetic modeling to identify three main factors linked to cognitive traits from the UK Biobank, revealing a moderate negative genetic correlation between these cognitive factors and schizophrenia.
  • Results show that while there's a shared genetic basis between cognitive abilities and schizophrenia, the genetic factors do not predict specific schizophrenia symptoms, suggesting distinct underlying genetic architectures for cognitive function and the disorder.
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  • * Neuroimaging reveals that many of these genetic variants have widespread effects on brain regions and are linked to various cancers and specific signaling pathways, such as p53 and Wnt.
  • * The findings suggest a connection between the genes that regulate head size and the likelihood of cancer, emphasizing the need for further research on the implications of this relationship.
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Article Synopsis
  • PTSD genetics have been difficult to study compared to other psychiatric disorders, limiting our biological understanding of the condition.
  • A large-scale meta-analysis involving over 1.2 million individuals identified 95 genome-wide significant loci, with 80 being new discoveries related to PTSD.
  • Researchers identified 43 potential causal genes linked to neurotransmitter activity, developmental processes, synaptic function, and immune regulation, enhancing our knowledge of the neurobiological systems involved in PTSD.
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Background: Incorporating genomic data into risk prediction has become an increasingly useful approach for rapid identification of individuals most at risk for complex disorders such as PTSD. Our goal was to develop and validate Methylation Risk Scores (MRS) using machine learning to distinguish individuals who have PTSD from those who do not.

Methods: Elastic Net was used to develop three risk score models using a discovery dataset (n = 1226; 314 cases, 912 controls) comprised of 5 diverse cohorts with available blood-derived DNA methylation (DNAm) measured on the Illumina Epic BeadChip.

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Article Synopsis
  • Cognitive impairment plays a significant role in the functionality of individuals with schizophrenia, prompting research into the genetic factors that contribute to this cognitive dysfunction.
  • Using advanced statistical methods on data from large studies, researchers identified three main cognitive factors (visuo-spatial, verbal analytic, decision/reaction time) that interconnect genetic correlations between cognitive traits and schizophrenia.
  • The study reveals a moderate negative genetic correlation between these cognitive factors and schizophrenia, with unique genomic regions influencing this relationship, and concludes that while shared genetic determinants exist, they do not predict specific schizophrenia symptoms.
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Reaction time variability (RTV), reflecting fluctuations in response time on cognitive tasks, has been proposed as an endophenotype for many neuropsychiatric disorders. There have been no large-scale genome-wide association studies (GWAS) of RTV and little is known about its genetic underpinnings. Here, we used data from the UK Biobank to conduct a GWAS of RTV in participants of white British ancestry (n = 404,302) as well as a trans-ancestry GWAS meta-analysis (n = 44,873) to assess replication.

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Article Synopsis
  • PTSD genetics are harder to study compared to other mental health disorders, resulting in limited biological insights from past research.
  • A large-scale analysis involving over 1.2 million individuals found 95 significant genetic loci related to PTSD, with 80 being new discoveries.
  • The study identified 43 potential causal genes linked to neurotransmitters, synaptic function, and immune responses, enhancing understanding of PTSD's biological mechanisms and suggesting new research directions.
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Background: The corpus callosum (CC) is a brain structure with a high heritability and potential role in psychiatric disorders. However, the genetic architecture of the CC and the genetic link with psychiatric disorders remain largely unclear. We investigated the genetic architectures of the volume of the CC and its subregions and the genetic overlap with psychiatric disorders.

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Background: Whereas genetic variants influencing total amygdala volume have been identified, the genetic architecture of its distinct nuclei has yet to be explored. We aimed to investigate whether increased phenotypic specificity through nuclei segmentation aids genetic discoverability and elucidates the extent of shared genetic architecture and biological pathways with related disorders.

Methods: T1-weighted brain magnetic resonance imaging scans (N = 36,352, 52% female) from the UK Biobank were segmented into 9 amygdala nuclei with FreeSurfer (version 6.

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Introduction: Cognitive dysfunction in schizophrenia may be assessed by measuring within-individual variability (WIV) in performance across a range of cognitive tests. Previous studies have found increased WIV in people with schizophrenia, but no studies have been conducted in low- to middle-income countries where the different sociocultural context may affect WIV. We sought to address this gap by exploring the relationship between WIV and a range of clinical and demographic variables in a large study of people with schizophrenia and matched controls in South Africa.

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Reaction time variability (RTV), reflecting fluctuations in response time on cognitive tasks, has been proposed as an endophenotype for many neuropsychiatric disorders. There have been no large-scale genome wide association studies (GWAS) of RTV and little is known about its genetic underpinnings. Here, we used data from the UK Biobank to conduct a GWAS of RTV in participants of white British ancestry ( = 404,302) as well as a trans-ancestry GWAS meta-analysis ( = 44,873) to assess replication.

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Background: Neurodevelopmental and mental health disorders in childhood constitute an emerging global concern, with adverse sequelae which span children's physical, psychological and social well-being. The aetiology of these disorders is likely complex, multifactorial and polygenic. Polygenic risk scores (PRS), an estimate of an individual's genetic liability toward a disorder, have been increasingly used in psychiatric research to explore genetic associations with disorders of interest.

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Adverse childhood experiences (ACES) increase risk for mental and physical health disorders in adulthood, particularly in individuals from sexual and ethnic minority groups. The effects of ACES on health may be mediated by the immune system. The exact mechanisms by which an environmental exposure, such as childhood adversity, can affect the immune system are still unknown.

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Schizophrenia is a neurodevelopmental disorder and a leading cause of disability worldwide. Deficits in cognitive function are characteristic of schizophrenia and are predictors of functional outcomes in the disorder. Within-individual variability (WIV) in cognitive performance is elevated in schizophrenia and has been suggested to provide additional insight into cognitive function over and above mean performance measures.

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 The objective of this study was to characterize the effect of preoperative variables on outcomes after minimally invasive lumbar microdiscectomy.  This study was done from January 2019 to May 2020. This included medical records of all patients who were diagnosed with lumbar disc herniation and treated surgically by microdiscectomy.

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African populations are the most diverse in the world yet are sorely underrepresented in medical genetics research. Here, we examine the structure of African populations using genetic and comprehensive multi-generational ethnolinguistic data from the Neuropsychiatric Genetics of African Populations-Psychosis study (NeuroGAP-Psychosis) consisting of 900 individuals from Ethiopia, Kenya, South Africa, and Uganda. We find that self-reported language classifications meaningfully tag underlying genetic variation that would be missed with consideration of geography alone, highlighting the importance of culture in shaping genetic diversity.

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Article Synopsis
  • Social genomics research shows that chronic social adversity (like discrimination and violence) can impact inflammatory and antiviral gene expression, increasing risks for conditions like HIV.
  • This study focused on HIV-positive Black and Latinx men who have sex with men (MSM) to see how methamphetamine use, unsuppressed HIV viral load, and intimate partner violence (IPV) affect immune response.
  • Results indicated that methamphetamine use greatly increased inflammatory and type I interferon expression; meanwhile, unsuppressed viral loads and experiences of IPV also predicted increases in these immune markers.
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Objectives: To summarise SNP associations identified by genome-wide association studies (GWASs) of anxiety disorders and neuroticism; to appraise the quality of individual studies, and to assess the ancestral diversity of study participants.

Methods: We searched PubMed, Scopus, PsychInfo and PubPsych for GWASs of anxiety disorders, non-diagnostic traits (such as anxiety sensitivity), and neuroticism, and extracted all SNPs that surpassed genome-wide significance. We graded study quality using Q-genie scores and reviewed the ancestral diversity of included participants.

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Article Synopsis
  • The human brain evolves over time, with changes in structure affecting mental health and diseases throughout life.
  • This study identifies genetic variants that influence brain growth and shrinkage, using data from 15,640 individuals and focusing on 15 brain structures.
  • Key genes linked to metabolism were found, highlighting connections to conditions like depression and schizophrenia, and suggesting that understanding these genetic factors could lead to insights about healthy and problematic brain development and aging.
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