A polygenic score for age‐at‐first‐birth predicts disinhibition – Leah Richmond‐Rakerd video abstract

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Leah Richmond‐Rakerd gives a video abstract of her paper ‘A polygenic score for age‐at‐first‐birth predicts disinhibition’ first published in Journal of Child Psychology & Psychiatry (JCPP) 27 March 2020. Read the Open Access paper doi.org/10.1111/jcpp.13224

A recent genome‐wide association study identified molecular‐genetic associations with age‐at‐first‐birth. However, the meaning of these genetic discoveries is unclear. Drawing on evidence linking early pregnancy with disinhibitory behavior, we tested the hypothesis that genetic discoveries for age‐at‐first‐birth predict disinhibition.

Full authors Leah S. Richmond‐Rakerd, Terrie E. Moffitt, Louise Arseneault, Daniel W. Belsky, Jennie Connor, David L. Corcoran, HonaLee Harrington, Renate M. Houts, Richie Poulton, Joey A. Prinz, Sandhya Ramrakha, Karen Sugden, Jasmin Wertz, Benjamin S. Williams, Avshalom Caspi.

Leah Richmond-Rakerd
Leah Richmond-Rakerd

Leah is currently a Postdoctoral Fellow with the Moffitt-Caspi Team in the Department of Pyschology and Neuroscience at Duke University.

She received her A.B. in Community Health from Brown University. She subsequently attended the University of Missouri, where she received her M.A. in Psychology followed in 2017 by her Ph.D. in Clinical Psychology with a Minor in Psychological Statistics and Methods. Leah is currently a Postdoctoral Fellow with the Moffitt-Caspi Team.

Leah’s research is focused on identifying the mechanisms underlying self-regulation difficulties across the life course. Through her work, Leah seeks to understand how genetic and environmental factors shape the developmental course of disinhibitory psychopathology and other health-risk behaviors, including self-harm and suicide. Leah’s research employs data from longitudinal and genetically-informative cohort studies, as well as large population-based government registers.

Follow on Twitter @LRakerd 

Transcript

My name is Leah Richmond-Rakerd.  I’m a Post-Doctoral Fellow in the Department of Psychology and Neuroscience at Duke University, and with the Carolina Consortium on Human Development at the University of North Carolina at Chapel Hill.  Today I’m going to provide a brief overview of a paper that my colleagues and I recently published in the ‘Journal of Child Psychology in Psychiatry’, titled, ‘A Polygenic Score for Age-at-First-Birth Predicts Disinhibition’.

In 2016 a genome-wide association study was published in which the authors identified molecular genetic associations with age-at-first-birth, or the age at which someone has their first child.  The purpose of our study was to clarify the meaning of these molecular genetic discoveries.  It’s possible that they capture the biological underpinnings of fertility.  But we thought that they might also capture the psychological traits and behaviors that go along with being a young parent.  So in this paper we tested the hypothesis that molecular genetic influences on age-at-first-birth, as measured by a polygenic score, would be associated with disinhibition across the life span.  We developed this hypothesis based on multiple lines of research that have linked early pregnancy with disinhibitory behavior.

Polygenic scores are derived from genome-wide association studies, and they aggregate millions of variants across the genome into the score that captures a person’s position on a continuum of genetic liability to a particular trait.  We derived a polygenic score for age-at-first-birth from the genome-wide association study, that I mentioned previously.  We tested the hypothesis that this polygenic score would predict disinhibition in two independent birth cohorts that together totaled about 3,000 participants.  These were the environmental risk, or E-Risk Longitudinal Twin Study, a UK cohort of twins followed to young adulthood, and the Dunedin Longitudinal Study, a New Zealand cohort of children followed to mid-life.

We assessed a range of disinhibitory outcomes in both cohorts.  We measured participants self control in childhood.  Measured their risk for externalizing psychopathology.  Obtained official Police records of their criminal offending.  Made diagnoses of substance dependence.  And obtained informant reports of their disinhibitory problems.   And measured their number of lifetime sexual partners.

Importantly, these outcomes were assessed across different developmental periods and using different methods, which allowed us to test the robustness of polygenic score associations.

We found that in both cohorts participants with lower polygenic scores, so individuals at greater genetic risk for having a child at an early age, had poor self control in childhood, or at greater risk for externalizing psychopathology, or more likely to have an official Police record of a crime, or more likely to have a substance dependence diagnosis, and had more lifetime sexual partners.  It’s important to note that the effect sizes for these associations were modest, so the genetic score explained a very small amount of the variants in the outcomes that we studied.  But the associations were robust across replication.

We also found that childhood self control partly mediated associations between the polygenic score and reproductive behaviors, including the ages at which individuals first had sexual intercourse, first became pregnant, and had their first child.  However, the polygenic score was not linked to accelerated puberty.  Taken together these findings suggest that associations with the score are not just about reproductive biology.  The age-at-first-birth score also appears to capture the disinhibitory traits and behaviors that go along with early parenthood.  And this indicates that age-at-first-birth could be a useful proxy phenotype for researchers who are interested in the genetic architecture of disinhibition.

This research was connected in collaboration with colleagues at Duke University, Kings College London, Columbia University, and the University of Otago.  I’d also like to acknowledge the funders that supported this study.  These include the National Institute on Aging.  The National Institute of Child Health and Human Development.  The UK Medical Research Council.  The Jacobs Foundations.  And the Avielle Foundation.

So thanks very much for watching this video abstract.  If you’d like to read the full paper it’s now available open access at the Journal of Child Psychology and Psychiatry’s website.

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