Abstract
Preterm birth is an extreme environmental stress associated with an increased risk of later cognitive dysfunction and mental health problems. However, the extent to which preterm birth is modulated by genetic variation remains largely unclear. Here, we test for an interaction effect between psychiatric polygenic risk and gestational age at birth on cognition at age four. Our sample comprises 4934 unrelated individuals (2066 individuals born < 37 weeks, 918 born < = 34 weeks). Genome-wide polygenic scores (GPS’s) were calculated for each individual for five different psychiatric pathologies: Schizophrenia, Bipolar Disorder, Major Depressive Disorder, Attention Deficit Hyperactivity Disorder and Autism Spectrum Disorder. Linear regression modelling was used to estimate the interaction effect between psychiatric GPS and gestational age at birth (GA) on cognitive outcome for the five psychiatric disorders. We found a significant interaction effect between Schizophrenia GPS and GA (β = 0.038 ± 0.013, p = 6.85 × 10–3) and Bipolar Disorder GPS and GA (β = 0.038 ± 0.014, p = 6.61 × 10–3) on cognitive outcome. Individuals with greater genetic risk for Schizophrenia or Bipolar Disorder are more vulnerable to the adverse effects of birth at early gestational age on brain development, as assessed by cognition at age four. Better understanding of gene-environment interactions will inform more effective risk-reducing interventions for this vulnerable population.
Highlights
+ β8(GA × sex) + β9(GA × socio‐economic status (SES)) + ε. The aim of this analysis was to investigate the effect of the interaction term GPSpsych × gestational age at birth (GA) on cognitive outcome
As a further exploration of our data, we looked at the extremes of the data undertaking a two-way analysis of variance (ANOVA) comparing mean cognition between the extreme quintiles of polygenic risk for individuals born at or below 34 weeks gestation and term-born (> = 37 weeks) individuals for the psychiatric pathologies that yielded significant results in our initial analysis
In addition to our interaction analysis we sought to confirm that gestational age in our cohort predicted cognitive outcome at four
Summary
Linear regression modelling was used to test for a possible gene-environment interaction between the GPS’s for five different psychiatric disorders (ASD, ADHD, Bipolar Disorder, Major Depressive Disorder and Schizophrenia) and gestational age at birth on cognition at age four. In addition to our linear regression analysis, considering gestational age and psychiatric genetic risk as continuous variables, we compared the effect of gestational age at birth on cognition for those individuals in the highest and lowest quintiles of the Schizophrenia and Bipolar Disorder GPS distributions. In this case two-way ANOVA analysis did not indicate a significant interaction effect between gestational age at birth and level of Bipolar Disorder genetic risk on cognition (F(1530) = 1.55 p = 0.213). None of the psychiatric genetic risk scores showed a significant association with cognition at age four (Supplementary Methods and Results and Supplementary Table S10), consistent with previous work in the literature[8]
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