The current findings support the hypothesis that disruption of the microbiome in infancy results in measurable, sex specific changes in behavioural characteristics associated with psychopathology. These early exploratory findings support further study into the mechanisms of potential behavioural effects of disruption of the human microbiome in infancy through exposure to antibiotics or birth by caesarean section. If a causal relationship is determined between early life microbiome disruptors and the development of psychopathology, the relative effect of these disruptors in relation to other developmental processes needs further consideration, given the potential impact these findings may have on the utilization of these intervention in infancy and early life. / Thesis / Master of Science (MSc)

Yes / Purpose: To investigate whether a genetic risk score (GRS) improved performance of predicting refractive error compared to knowing a child’s number of myopic parents (NMP) alone. Methods: This was a retrospective analysis of data from the Avon Longitudinal Study of Parents and Children (ALSPAC) birth cohort study. Refractive error was assessed longitudinally between age 7–15 using non-cycloplegic autorefraction. Genetic variants (n=149) associated with refractive error from a Consortium for Refractive Error And Myopia (CREAM) genome-wide association study were used to calculate a GRS for each child. Using refractive error at ages 7 and 15 years as the outcome variable, coefficient of determination (R2) values were calculated via linear regression models for the predictors: NMP, GRS and a combined model. Results: Number of myopic parents was weakly predictive of refractive error in children aged 7 years, R2=3.0% (95% CI 1.8–4.1%,p<0.0001) and aged 15 years, R2=4.8% (3.1–6.5%,p<0.0001). The GRS was also weakly predictive;age 7 years, R2=1.1% (0.4–1.9%,p<0.0001) and 15 years R2=2.6% (1.3–3.9%,p<0.0001). Combining the 2 variables gave larger R2 values at age 7, R2=3.7%(2.5–5.0%,p<0.0001) and 15, R2=7.0% (5.0–9.0%,p<0.0001). The combined model improved performance at both ages (both p<0.0001). Conclusion: A GRS improved the ability to detect children at risk of myopia independently of knowing the NMP. We speculate this may be because NMP captures information concerning environmental risk factors for myopia. Nevertheless, further gains are required to make such predictive tests worthwhile in the clinical environment. / The UK Medical Research Council and Wellcome. Grant Number: 102215/2/13/2 The University of Bristol provide core support for ALSPAC PDF. Grant Number: 459KB The College of Optometrists NIHR Senior Research Fellowship. Grant Number: SRF‐2015‐08‐005 23andMe

A baby’s early experiences have a crucial effect on their later development and adjustment. Early maternal sensitivity is a concept which has been associated with a crucial influence on these later child outcomes, including behavioural outcomes. Results from large longitudinal population based studies have provided conflicting evidence in relation to early maternal sensitivity, particularly sensitivity to non-distress, and later child behaviour and a need for further research in this area exists. The current study investigated early maternal sensitivity and its association with later child behaviour in a UK based population sample using data from the Avon Longitudinal Study of Parents and Children (ALSPAC). The study used a subsample of 766 mother-infant pairs who had data on observed maternal responsiveness at 12 months and on child behavioural difficulties derived from the Revised Rutter Parent Scale for Preschool Children at 42 months. Data for a number of potentially confounding variables, including maternal and child-based variables were also included in the analysis. Hypotheses were tested regarding an association between lower maternal responsiveness and higher child behavioural difficulties as well as regarding associations with further behavioural subscales of the Rutter scale, including a prosocial behaviour subscale. Results were analysed using a linear regression model with adjustments for groups of confounding variables. There was no evidence to support a relationship between lower maternal responsiveness and higher behavioural difficulties at 42 months although there was suggestion of a trend in the expected direction. Similar results were found for the subscales of the Rutter scale. The conclusion is that maternal sensitivity measured in this way does not have a strong relationship with child behaviour. One interpretation of these results is that there is a need to distinguish between maternal sensitivity to non-distress and to distress and ensure that the appropriate aspect of maternal sensitivity in relation to child behavioural outcomes is assessed. Limitations of the study are discussed and the effects of potential improvements are considered.

Fathers in two-parent families are becoming increasingly involved in infant care, highlighting the need to understand the determinants and influence of father-infant interactions. Paternal responsiveness is a core component of positive father-infant interactions. This study investigated associations between paternal responsiveness and infant development; and paternal low mood and paternal responsiveness. Participants were a sub-sample of father-infant dyads (n=47) from a UK community cohort study: The Avon Longitudinal Study of Parents and Children. The Mellow Parenting Coding System was used to measure paternal responsiveness within a video-recorded father-infant interaction at 12 months. Infant development was assessed using the Griffiths scales at 18 months and paternal low mood was measured using the Edinburgh Post-Natal Depression Scale (EPDS) at 8 months. Linear regression analysis provided no evidence for an association between paternal responsiveness and infant development. Due to methodological limitations it is unclear whether this reflects a true null relationship. Unexpectedly, lower paternal mood (indicated by higher scores on the EPDS), was found to be associated with greater paternal responsiveness. For every standard deviation increase in EPDS score, fathers displayed approximately two additional responsiveness behaviours per minute in the observed interaction; this corresponds to a standardised effect size of 0.32 standard deviations. The mechanisms for this association are unclear, but possibilities are discussed. The finding requires replication within larger studies, but clinicians may wish to consider that fathers who achieve very low scores on measures of depressed mood may be at risk for low paternal responsiveness.

Attention deficit/hyperactivity disorder (ADHD) is commonly reported to be more prevalent in children from socioeconomically disadvantaged backgrounds. In this thesis I will explore in more detail the association between socioeconomic disadvantage and ADHD. This thesis comprises six studies, starting with a systematic review in order to evaluate existing published evidence, which is followed by a qualitative study that explores educational practitioners’ conceptualisation of the causes of ADHD. A series of three analyses utilising existing data from the Avon Longitudinal Study of Parents and Children (ALSPAC) then explore which measures of socioeconomic status (SES) are associated with a research diagnosis of ADHD and potential mediators of this association, and whether timing, duration or changes in exposure to financial difficulty impact on the SES-ADHD association. In the final study in this thesis, I explore whether SES-health associations in general are likely to be due to epigenetic differences in children exposed to low SES. Existing literature provides evidence that an association between SES and ADHD is commonly detected. The facet of SES most predictive of ADHD was mother-reported experience of difficulty affording basic necessities (financial difficulty), associated with an increased risk of a research diagnosis of ADHD of 2.23 (95%CI 1.57, 3.16). Exposure to financial difficulty between birth and age seven was associated with higher levels of ADHD symptoms across childhood of 0.78 points on the Strengths and Difficulties Questionnaire Hyperactivity subscale (95% CI 0.54, 1.00, p < 0.001), whereas later exposure to financial difficulty was not associated with ADHD symptoms. In addition, I found tentative evidence that different patterns of SES exposure are associated with different levels of ADHD symptoms, with those consistently low SES having symptom scores 0.41 points higher than those in difficulty (95% CI 3.46, 3.57, p<0.001). I did not find strong evidence that low SES impacts on epigenetic profiles across childhood. These findings add to emerging evidence of an association between SES and ADHD that has implications for theory and policy.

Yes / PURPOSE. To test the hypothesis that emmetropization buffers against genetic and environmental risk factors for myopia by investigating whether risk factor effect sizes vary depending on children’s position in the refractive error distribution. METHODS. Refractive error was assessed in participants from two birth cohorts: Avon Longitudinal Study of Parents and Children (ALSPAC) (noncycloplegic autorefraction) and Generation R (cycloplegic autorefraction). A genetic risk score for myopia was calculated from genotypes at 146 loci. Time spent reading, time outdoors, and parental myopia were ascertained from parent-completed questionnaires. Risk factors were coded as binary variables (0 = low, 1 = high risk). Associations between refractive error and each risk factor were estimated using either ordinary least squares (OLS) regression or quantile regression. RESULTS. Quantile regression: effects associated with all risk factors (genetic risk, parental myopia, high time spent reading, low time outdoors) were larger for children in the extremes of the refractive error distribution than for emmetropes and low ametropes in the center of the distribution. For example, the effect associated with having a myopic parent for children in quantile 0.05 vs. 0.50 was as follows: ALSPAC: age 15, –1.19 D (95% CI –1.75 to –0.63) vs. –0.13 D (–0.19 to –0.06), P = 0.001; Generation R: age 9, –1.31 D (–1.80 to –0.82) vs. –0.19 D (–0.26 to –0.11), P < 0.001. Effect sizes for OLS regression were intermediate to those for quantiles 0.05 and 0.50. CONCLUSIONS. Risk factors for myopia were associated with much larger effects in children in the extremes of the refractive error distribution, providing indirect evidence that emmetropization buffers against both genetic and environmental risk factors. / UK Medical Research Council and Wellcome (grant ref: 102215/2/13/2), and the University of Bristol provided core support for ALSPAC. This research was specifically funded by the UK National Eye Research Centre (grant SAC015), the Global Education Program of the Russian Federation government, a PhD studentship grant from the UK College of Optometrists (“Genetic Prediction of Individuals At-Risk for Myopia Development”), and an NIHR Senior Research Fellowship award SRF-2015-08-005. The Generation R study is supported by the Erasmus Medical Center, Rotterdam, Erasmus University, Rotterdam, the Netherlands; the Netherlands Organization of Scientific Research (NWO); Netherlands Organization for the Health Research and Development (ZonMw); the Ministry of Education, Culture and Science; the Ministry for Health,Welfare and Sports; the European Commission (DG XII); European Research Council (ERC) under the European Union’s Horizon 2020 Research and Innovation Programme (grant 648268); the Netherlands Organization for Scientific Research (NWO, grant 91815655); and Oogfonds, ODAS, Uitzicht 2017-28 (LSBS, MaculaFonds, Oogfonds).

Physical inactivity among young people is a public health concern. Markers of physical inactivity, such as low cardio-respiratory fitness (CRF) and obesity are adversely related to higher order cognitive functions, which underpin goal directed behaviour (i.e. cognitive control) and are implicated in academic achievement. Regular aerobic exercise can benefit cognitive control in children. However, it remains unknown whether daily physical activity behaviour is associated with cognitive control. Investigating this is important as targeting increments in daily moderate-to-vigorous physical activity (MVPA) may initially be a more realistic policy goal than developing aerobic exercise interventions. Nominal number of studies assessed this relationship using objective monitoring of physical activity (accelerometry), and yielded mixed results. None of the studies into objectively measured physical activity and cognitive function in young people controlled for CRF, which is posited to mediate the relationship between regular aerobic exercise and cognitive control. Likewise, other important confounders such as intelligence, have yet to be addressed in the literature. Moreover, it is unknown whether this relationship varies with age, as extant studies looked solely at younger adolescents. For example, meta-analytical findings (Fedewa & Ahn, 2011) suggest that children can benefit more cognitively from CRF and chronic aerobic exercise than adolescents as greater effect sizes have been observed for younger compared to older youngsters. Alternatively, chronic aerobic exercise may be specifically needed for cognitive benefits to emerge. However, none of the aerobic exercise interventions included objective assessments of baseline physical activity and few studies assessed the effects of chronic aerobic exercise interventions on multiple indices of cognitive control. This thesis aimed to address the limitations of previous research and to investigate: 1) the associations between objectively measured daily MVPA and cognitive control in older adolescents (study 1), and 2) in preadolescent children (study 2), while controlling for CRF, general intellectual ability and a number of important confounders (e.g. adiposity, attention-deficit hyperactivity disorder); 3) the relationship between daily MVPA and academic achievement (study 2); 4) the effects of chronic aerobic exercise intervention on cognitive control in children, while controlling for objectively measured daily MVPA and time sedentary at baseline (study 3). Methods: Study 1. A sample of 667 adolescents (Mage = 15.4, SD = .17, 55.5% girls) from the Avon Longitudinal Study of Parents and Children was included in the analyses. MVPA was measured with ActiGraph, GT1M accelerometer. CRF was assessed with sub-maximal cycle ergometer test and expressed as weight adjusted predicted physical work capacity at the heart rate of 170 beats per minute (PWC-170). Attentional control was measured with Stop Signal task. Study 2. A sample of 81 children (Mage = 8.64 years, SD = .57, 45.7 % girls) was included in the analyses. MVPA was objectively measured using the ActiGraph, wGT3X+ accelerometer. CRF was measured using a maximal graded exercise test on a treadmill. Inhibitory control was assessed with a modified Eriksen flanker task, working memory with Operation Span Task; and academic achievement with Kaufman Test of Educational Achievement. Study 3. 32 children (Mage = 8.64, SD = .58, 56.2% girls) were randomised into a physical activity intervention (FITKids2) or a waitlist control group. Changes in VO2max were measured using a maximal graded treadmill exercise test and changes in MVPA were objectively monitored for 7 days using the ActiGraph, wGT3X+ accelerometer. Behavioural measures of inhibition (reaction time, and accuracy) and working memory (accuracy) were taken using computerised laboratory tasks (modified Eriksen flanker task and Operation Span Task). Results: Study 1. MVPA was not significantly related to cognitive processing speed or variability of cognitive performance in hierarchical linear regression models. In simple regression models, CRF was negatively related to mean RT on the simple go condition (R2 = 2.6%, F(1, 308) = 8.28, p = .004). Study 2. No significant associations were noted between MVPA and either inhibition, working memory, or academic achievement. In contrast, CRF explained 4.7% of variance in accuracy interference (ΔR2 = .047, p = .045; β = -.22, t(78) = 2.03, p = .045, F(2, 78) = 4.95, p = .009). Study 3. FITKids2 physical activity intervention had a positive effect on the speed of responding during incongruent condition of flanker task (F(1, 30) = 4.69, p = .038, ηp2 = .13). A significant increase in BMI percentile was observed in the control (Z = 2.17, p = .03) but not in the intervention group (p = .53). Discussion: Study 1. Our results suggest that aerobic fitness, but not MVPA, was associated with cognitive processing speed under less cognitively demanding task conditions. The results thus indicate a potential global effect of aerobic fitness on cognitive functions in adolescents but this may differ depending on the specific task characteristics. Study 2. The results of this study suggest that CRF but not objectively measured MVPA was associated with better interference control in preadolescent children. Given the intermittent nature of children s daily MVPA, it is possible that aerobic exercise, which increases CRF is needed for cognitive benefits to emerge. Study 3. FITKids2 after-school physical activity intervention had a positive effect on children s inhibitory control, namely this cognitive function, which is closely related to academic achievement and future job and health outcomes. Thus, the results of this study convey a positive public health message, where promoting child s engagement in aerobic exercise can engender benefits to their cognitive function. Conclusions: The findings from this thesis can inform development of physical activity interventions to benefit cognitive functions in young people and contribute to the evidence base to inform future health and educational policies.

Background: Evidence from experimental studies suggests that atrazine and its analytes alter the timing of puberty in laboratory animals. Such associations have not been investigated in humans. Objective: To determine the association between in utero exposure to atrazine analytes and earlier menarche attainment in a nested case-control study of the population-based Avon Longitudinal Study of Parents and Children. Methods: Cases were girls who reported menarche before 11.5 years while controls were girls who reported menarche at or after 11.5 years. Seven atrazine analyte concentrations were measured in maternal gestational urine samples (sample gestation week median (IQR): 12 (8–17)) during the period 1991–1992, for 174 cases and 195 controls using high performance liquid chromatography-tandem mass spectrometry. We evaluated the study association using multivariate logistic regression, adjusting for potential confounders. We used multiple imputation to impute missing confounder data for 29% of the study participants. Results: Diaminochlorotriazine (DACT) was the most frequently detected analyte (58%>limit of detection [LOD]) followed by desethyl atrazine (6%), desethyl atrazine mercapturate (3%), atrazine mercapturate (1%), hydroxyl atrazine (1%), atrazine (1%) and desisopropyl atrazine (0.5%). Because of low detection of other analytes, only DACT was included in the exposure–outcome analyses. The adjusted odds of early menarche for girls with DACT exposures≥median was 1.13 (95% Confidence Interval [95% CI]:0.82, 1.55) and exposure Conclusions: This study is the first to examine the association between timing of menarche and atrazine analytes. We found a weak, non-significant association between in-utero exposure to atrazine metabolite DACT and early menarche, though the association was significant in the subset of girls with complete confounder information. Further exploration of the role of these exposures in female reproduction in other cohorts is needed.

Alcohol use disorder is a global health issue that affects a significant portion of the population, with affects including both negative mental and physical consequences. Currently, there are few treatment options available to those who suffer from alcohol use disorder, alcohol abuse, or alcohol dependence. Identifying candidate genes or environmental influences would therefore improve the means for possible treatments or identification of those people at risk for alcohol use disorder. Previous studies in humans have demonstrated an inverse association between initial sensitivity and risk for alcohol abuse. This connection allows investigators, and our laboratory, to investigate genetic and environmental factors that may influence initial ethanol sedation. Our laboratory utilizes Drosophila melanogaster (flies) as a model organism to identify these such factors influencing acute behavioral responses to alcohol. Our lab has found evidence for both environmental and genetic factors that influence initial alcohol sensitivity in flies. In one study, flies that are fed increased amounts of dietary yeast are resistant to ethanol. We have found that this ethanol resistance is related to the amount of nutrients that is consumed, which then affects alcohol uptake/metabolism, to influence initial alcohol sensitivity. Importantly, we found that serotonergic neuron function is essential for regulating the consumption of high dietary yeast media for the increased nutrient intake to occur. In two separate projects, we identified a role for myocyte enhancer factor 2 (Mef2) and nitric oxide synthase (Nos) in initial alcohol sensitivity. Mef2 was obtained via a GWAS study identifying genes with an association with initial sensitivity in humans. We found that decreasing or altering Mef2 expression, using mutants or Mef2 RNAi, resulted in flies having decreased sensitivity to alcohol. The gene Nos, came out of a previous genetic interaction screen in the laboratory. Multiple reagents to assess Nos’s role in alcohol behavior were obtained and consistent evidence from three piggyBac transposon insertion flies and, importantly, a Nos null fly, demonstrate that decreased Nos expression results in increased ethanol sensitivity. Other preliminary results suggest that Nos expression during adulthood, as well as the mechanism of S-nitrosation, may be important for ethanol sedation in Drosophila.

Background: Research exploring the developmental of adolescent antisocial behaviour suggests that a secure attachment style is a protective factor against problem behaviour (Bowlby, 1969). It is theorised that disruptions in the attachment relationship can increase the likelihood of adjustment difficulties in adolescence, including antisocial behaviour (MacDonald, 1985). Such relationships have been inferred by cross-sectional research studies, but have yet to be tested in a longitudinal sample. Aims: This research is a secondary data analysis, using data from the Avon Longitudinal Study of Parents and Children cohort study, to explore the relationship between attachment and adolescent antisocial behaviour at age 15.5 years. Attachment was measured using three component measures; maternal sensitivity in infancy (sample 1), separations from main caregiver in early childhood, age 3-5 years (sample 2) and the presence of separation anxiety in middle childhood, age 81 months, 6.75 years (sample 3). Results: Logistic regression analyses were used to explore the relationships. Using available data, in sample 1 (n=456 complete cases) no evidence was found to support an association between non-positive maternal sensitivity in infancy and an increased incidence of adolescent antisocial behaviour (OR=0.79 [CI=0.42-1.48], p=0.46). In sample two (n=3,961), the number of separations in infancy were not found to significantly increase the risk of adolescent antisocial behaviour (OR=1.26 [CI=0.94-1.71], p=0.17). Separation anxiety in middle childhood was not found to have an effect on adolescent antisocial behaviour (OR=1.01 [CI=0.80-1.26], p=0.96). Conclusions: The findings suggest that although components of attachment, as measured in this study, were hypothesised to be associated with an increased risk of adolescent antisocial behaviour, this was not statistically supported in this study. In this study effects may be limited due to attrition, leading to the loss of antisocial adolescents from the study, creating a bias in the sample studied.