Ziada Ayorech

Ziada Ayorech
King's College London | KCL · MRC Social, Genetic and Developmental Psychiatry Centre

Doctor of Philosophy in Behavioral Genetics

About

61
Publications
5,170
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360
Citations
Citations since 2017
56 Research Items
327 Citations
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2017201820192020202120222023020406080

Publications

Publications (61)
Article
Full-text available
Fundamental questions about the roles of genes, environments, and their interplay in developmental psychopathology have traditionally been the domain of twin and family studies. More recently, the rapidly growing availability of large genomic datasets, composed of unrelated individuals, has generated novel insights. However, there are major stumbli...
Article
Full-text available
The increase in online media use and mental health problems have prompted investigations into their association, although most literature is focussed on deleterious effects. We assessed the aetiology of media use and mental health associations ( M age = 22.14, SD = 0.85) using twin (n = 4000 pairs) and polygenic score methods (n = 6000 unrelated in...
Preprint
The widespread comorbidity observed across psychiatric disorders may be the result of processes such as assortative mating, gene-environment correlation, or selection into population studies. Between-family analyses of comorbidity are subject to these sources of bias, whereas within-family analyses are not. Because of Mendelian inheritance, alleles...
Article
Full-text available
Background: Higher BMI in childhood is associated with emotional and behavioural problems, but these associations may not be causal. Results of previous genetic studies imply causal effects but may reflect influence of demography and the family environment. Methods: This study used data on 40,949 8-year-old children and their parents from the No...
Article
Full-text available
A child’s environment is thought to be composed of different levels that interact with their individual genetic propensities. However, studies have not tested this theory comprehensively across multiple environmental levels. Here, we quantify the contributions of child, parent, school, neighbourhood, district, and municipality factors to achievemen...
Article
Full-text available
Background: Theoretical models of the development of childhood externalizing disorders emphasize the role of parents. Empirical studies have not been able to identify specific aspects of parental behaviors explaining a considerable proportion of the observed individual differences in externalizing problems. The problem is complicated by the contri...
Article
Background: Children with ADHD tend to achieve less than their peers in school. It is unknown whether schools moderate this association. Nonrandom selection of children into schools related to variations in their ADHD risk poses a methodological problem. Methods: We linked data on ADHD symptoms of inattention and hyperactivity and parent-child A...
Preprint
A child’s environment is thought to be composed of different levels that interact with individual genetic propensities, with less advantaged environments suppressing genetic effects on achievement. However, studies have not tested this theory comprehensively across multiple environmental levels. Here, we quantify the contributions of child, parent,...
Article
Full-text available
Here we report the results of the first systematic investigation of genetic and environmental influences on 57 psychological traits covering major issues in emerging adulthood such as aspirations, thoughts and attitudes, relationships and personality. We also investigate how these traits relate to physical and mental health, educational attainment...
Preprint
Background: Children with ADHD tend to achieve less than their peers in school. It is unknown whether schools moderate this ADHD deficit. Selection into schools poses a methodological problem.Methods: We linked data on ADHD symptoms of inattention and hyperactivity and parent-child ADHD polygenic scores (PGS) from the Norwegian Mother, Father, and...
Preprint
Co-occurring national rises in online media use and mental health problems have prompted investigations into their association, although most of this literature is focussed on the deleterious effects of media exposure. We assessed phenotypic associations between media use and mental health in young adulthood (M age= 22.14) and their aetiology using...
Article
Full-text available
Background: Attention deficit/hyperactivity disorder (ADHD), autism spectrum disorder (autism) and schizophrenia are highly heritable neurodevelopmental disorders, affecting the lives of many individuals. It is important to increase our understanding of how the polygenic risk for neurodevelopmental disorders manifests during childhood in boys and...
Preprint
Full-text available
Objectives: Higher BMI in childhood predicts neurodevelopmental and emotional problems, but it is unclear if these associations are causal. Previous genetic studies imply causal effects of childhood BMI on depression and attention-deficit hyperactivity disorder (ADHD), but these observations might also reflect effects of demography and the family e...
Article
Full-text available
Background Timing of developmental milestones, such as age at first walking, is associated with later diagnoses of neurodevelopmental disorders. However, its relationship to genetic risk for neurodevelopmental disorders in the general population is unknown. Here, we investigate associations between attainment of early-life language and motor develo...
Preprint
Full-text available
Importance: Economic and racial inequality is linked to disparities in children's mental health. Biomarkers that reflect these social disparities are lacking. Objective: We examined the hypothesis that salivary DNA-methylation patterns of higher inflammation and faster pace of biological aging are economically, racially and ethnically stratified an...
Article
Background Higher BMI in childhood predicts subsequent neurodevelopmental and emotional problems, but it is unclear if associations are causal. Observational studies are vulnerable to reverse causation and confounding. Mendelian randomization (MR) studies with unrelated individuals can also suffer from familial biases, such as dynastic effects (“ge...
Preprint
Anorexia nervosa (AN) polygenic liability has been associated with mental health traits, eating problems, and body mass index (BMI) in adolescence and adulthood, but little is known about its manifestations in early childhood. We explore AN polygenic score (PGS) associations with six childhood domains: BMI, eating problems, neurodevelopment, emotio...
Preprint
Full-text available
In the 21st century, emerging adulthood has stretched from the late teens through the twenties. Although this extended transition to adulthood can create stress, it can also offer opportunities to explore vocations and relationships that provide a better fit to individuals proclivities, including their genetic propensities. Here we report the resul...
Article
Genetic liability for schizophrenia is associated with psychopathology in early life. It is not clear if these associations are time dependent during childhood, nor if they are specific across different forms of psychopathology. Using genotype and questionnaire data on children (N = 15 105) from the Norwegian Mother, Father and Child Cohort Study,...
Preprint
Background Attention deficit/hyperactivity disorder (ADHD), autism spectrum disorder (autism), and schizophrenia, are highly heritable neurodevelopmental disorders, affecting the lives of many individuals. To improve prevention and treatment, it is important to increase our understanding of how the polygenic risk for neurodevelopmental disorders ma...
Preprint
Background Early developmental milestones, such as the age at first walking or talking, are associated with later diagnoses of neurodevelopmental disorders, but the relationship to genetic risk for neurodevelopmental disorders are unknown. Here, we investigate associations between genetic liability to autism spectrum disorder (autism), attention de...
Preprint
Full-text available
Background Genetic liability for schizophrenia is associated with psychopathology in early life. It is not clear if these associations are time-dependent during childhood, nor if they are specific across different forms of psychopathology. Methods Using genotype and questionnaire data on children (N = 15,105) from the Norwegian Mother, Father, and...
Article
Full-text available
Background The rise of social media use in young people has sparked concern about the impact of cyber-victimisation on mental health. Although cyber-victimisation is associated with mental health problems, it is not known whether such associations reflect genetic and environmental confounding. Methods We used the co-twin control design to test the...
Article
Full-text available
The two best predictors of children’s educational achievement available from birth are parents’ socioeconomic status (SES) and, recently, children’s inherited DNA differences that can be aggregated in genome‐wide polygenic scores (GPS). Here we chart for the first time the developmental interplay between these two predictors of educational achievem...
Preprint
Full-text available
The two best predictors of children's educational achievement available from birth are parents' socioeconomic status (SES) and, recently, children's inherited DNA differences that can be aggregated in genome-wide polygenic scores (GPS). Here we chart for the first time the developmental interplay between these two predictors of educational achievem...
Article
At the end of compulsory schooling, young adults decide on educational and occupational trajectories that impact their subsequent employability, health and even life expectancy. To understand the antecedents to these decisions, we follow a new approach that considers genetic contributions, which have largely been ignored before. Using genome-wide p...
Article
Full-text available
University success, which includes enrolment in and achievement at university, as well as quality of the university, have all been linked to later earnings, health and wellbeing. However, little is known about the causes and correlates of differences in university-level outcomes. Capitalizing on both quantitative and molecular genetic data, we perf...
Article
Full-text available
Background Maternal smoking during pregnancy (MSDP) has been linked to offspring's externalizing problems. It has been argued that socio-demographic factors (e.g. maternal age and education), co-occurring environmental risk factors, or pleiotropic genetic effects may account for the association between MSDP and later outcomes. This study provides a...
Article
Full-text available
Using twin (6,105 twin pairs) and genomic (5,825 unrelated individuals taken from the twin sample) analyses, we tested for genetic influences on the parent-offspring correspondence in educational attainment. Genetics accounted for nearly half of the variance in intergenerational educational attainment. A genomewide polygenic score (GPS) for years o...
Article
Full-text available
Online media use has become an increasingly important behavioral domain over the past decade. However, studies into the etiology of individual differences in media use have focused primarily on pathological use. Here, for the first time, we test the genetic influences on online media use in a UK representative sample of 16 year old twins, who were...
Data
Factor analyses on media use variables. (DOCX)
Data
Total variance explained in media use factor analysis. (DOCX)
Data
Factor analyses on Facebook use variables. (DOCX)
Data
Sex limitation sub-model comparisons: Factorized educational screen time. (DOCX)
Data
Portion of questionnaire assessing Facebook use. (DOCX)
Data
Portion of questionnaire assessing online media use. (DOCX)
Data
Total variance explained in Facebook factor analysis. (DOCX)
Data
Sex limitation model fitting results with 95% confidence intervals, depicting A, C and E estimates separately for males and females. (DOCX)
Data
Sex limitation sub-model comparisons: Factorized entertainment screen time. (DOCX)
Data
Sex limitation sub-model comparisons: Facebook Factor. (DOCX)
Data
Proportion of time spent on different forms of media for total sample and across gender and zygosity. (DOCX)
Data
Sex limitation sub-model comparisons: Factorized gaming. (DOCX)
Article
Full-text available
We document the growth in published papers on behavioral genetics for 5-year intervals from 1960 through 2014. We used 1861 papers published in Behavior Genetics to train our search strategy which, when applied to Ovid PsychINFO, selected more than 45,000 publications. Five trends stand out: (1) the number of behavioral genetic publications has gro...
Article
Full-text available
We have previously shown that individual differences in educational achievement are highly heritable throughout compulsory education. After completing compulsory education at age 16, students in England can choose to continue to study for two years (A-levels) in preparation for applying to university and they can freely choose which subjects to stu...
Article
Inflammation has emerged as a potentially important factor - and thus putative pharmacological target - in the pathology of bipolar disorders. However to date no systematic evaluations of the efficacy of add on anti-inflammatory treatment for the depressive and manic episodes have been carried out. Sixteen articles were ultimately identified - by c...
Article
Full-text available
Drug-associated environmental stimuli elicit craving in humans and drug-seeking in animals. We tested the hypothesis that Pavlovian-conditioned alcohol-seeking is mediated by dopamine, using rats from two vendors. Male, Long-Evans rats (220-240 g) from Charles River (St-Constant, QC, Canada) and Harlan Laboratories (Indianapolis, IN, USA) received...

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