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Reporting period: 2020-01-01 to 2020-06-30

• What is the problem/issue being addressed?

The overall goal of the LIFECOURSE study is to improve our understanding of how individual differences and environmental living conditions from birth through adolescence interact to influence the development of emotional reactions to stress such as depression and anxiety as well as behaviours such as substance use, self-harm, suicidal behaviour, and delinquency. The theoretical framework for the study is comprised with a combination of theories from sociology and criminology, developmental psychology, and biology. The study design is a unique developmental cohort study that covers the entire early lifespan of a birth cohort of children born, and residing in, Reykjavik, Iceland, in the year 2000 (N = 1,151), and a sample of all children born in the country of Iceland in the year 2004 (N = 4,234). Three retrospective and prospective data sources comprise the study base: a) retrospective registry data assembled from national data banks, b) prospectively collected biomarker samples, and c) repeated-measures social surveys.

• Why is it important for society?

While we know quite a lot about the effects of the environment on different outcomes there still are gaps in our knowledge as to how the environment and biology interact in affecting these outcomes. In Iceland, a successful environmental community-based prevention and health promotion program has been run for over twenty years, with the aim of decreasing the likelihood of alcohol and substance use by adolescents from being some of the highest in Europe, to being among the lowest in most categories over a 20 year period. However, in spite of its success, consistently every year, around 5 to 10 % of adolescents initiate some form of substance abuse. This fact is one of the driving forces of the LIFECOURSE project, telling us that understanding the effects of the environment on its own is not sufficient. We need to study the interplay between environmental and biological factors in explaining emotional and behavioral outcomes in adolescent lives. Iceland provides an excellent setting for the project as the country is enthusiastic about societal data collection, with the first census carried out in the year 1703. A large amount of data is routinely collected with individual identification codes, from pre-birth to adulthood, albeit with much of it only being accessible in separate databases that are not cross-linked for analyses. The LIFECOURSE study represents the first multilevel cohort study that combines biological, behavioural, and social data from before birth through adolescence for an entire population birth cohort of adolescents.

• What are the overall objectives?

The overall objectives of the LIFECOURSE project seek to answer how stress affects physiology, emotions and behaviour in the lives of adolescents, how the community level and the individual level of stress interact over time, and whether the impact of childhood stress is reversible during adolescence and in young adulthood. The holistic gathering of data has taken five years and currently represents an infrastructure of data that is available to answer these questions in numerous publications for years to come. The data will be made available to scientists from the social and behavioral sciences, health sciences and the life sciences.
Data for the project is an amalgamation of official registry sources from several centralized health registries in Iceland, the Educational Testing Institute, and the Statistical Bureau. The registry data sources are then supplemented with both survey data and bio-samples from participants. Two cohorts of children participated in the project; the 2000 birth cohort born in the city of Reykjavik, and the entire 2004 cohort born in Iceland.
From the beginning of the project, our focus has been on assembling data from registry sources from the cohort of children born in Iceland the year 2004. These include collection of pre-natal care and post-natal care records, data from Child Protection Services, from the Directorate of Education and the Icelandic elementary-school health data base (ISKRA). Three waves of school-based surveys were implemented amongst the 2004 cohort in February 2017, 2018 and 2019 and biomarkers from saliva samples at one time point.

So far, six peer-reviewed journal articles have been published and a few more either being written by the projects scientific team or under peer review for publication. See a list of publications below:

Halldorsdottir, T., Kristjansson, A.L. Asgeirsdottir, B.B. Thorisdottir, I.E. Sigfusson, J., Jonsdottir Tolgyes, E.M. Valdimarsdottir, H.B. Allegrante, J., & Sigfusdottir, I.D. (2020). A multi-level developmental approach towards understanding adolescent mental health and behaviour: Rationale, design and methods of the LIFECOURSE study in Iceland. Social Psychiatry and Psychiatric Epidemiology. doi: 10.1007/s00127-020-01995-6
Thorisdottir, IE., Sigurvinsdottir, R., Kristjansson, AL., Allegrante, JP., Lilly, CL., Sigfusdottir, ID. (2020). Longitudinal association between social media use and psychological distress among adolescents. Preventive Medicine, 141, 106270. DOI: 10.1016/j.ypmed.2020.106270
Kristjansson, AL., Thomas, S., Lilly, CL., Thorisdottir, IE., Allegrante, JP., Sigfusdottir, ID. (2018). Maternal Smoking during Pregnancy and Academic Achievement of Offspring over Time: A Registry Data-Based Cohort Study. Preventive Medicine, 113, 74-79.
Kristjansson, AL., Thorisdottir, IE., Steingrimsdottir, T., Allegrante, JP., Lilly, CL., Sigfusdottir, ID. (2017). Maternal Smoking during Pregnancy and Scholastic Achievement in 4th, 7th and 10th grade: Evidence from the LIFECOURSE Cohort Study. European Journal of Public Health, 27(5), 850 – 855.
Ragnarsdottir, LD., Kristjansson, AL., Thorisdottir, IE., Allegrante, JP., Valdimarsdottir, HB., Gestsdottir, S., Sigfusdottir ID. (2017). Cumulative Risk over the Early Life Course and its Relations to Academic Achievement in Childhood and Early Adolescence. Preventive Medicine, 96, 36 – 41.
Sigfusdottir, I.D. Kristjansson, A.L. Thorlindsson, T., Allegrante, J.P. (2017). Stress and adolescent well-being: The need for an interdisciplinary framework. Health Promotion International, 32 (6), 1081 – 1090.
Leveraging the multi-level framework, we are currently working on numerous papers aimed at identifying individual, societal and biological factor shape child and adolescent mental health outcomes and harmful behaviors.