So much of paediatrics, and medicine in general, is focused on small experimental or observational studies. This series of posts takes the wider view; we’re talking about some of the biggest and longest-running studies that help us frame, measure and understand childhood through time and worldwide. This one is from Dunedin, Aotearoa
Who and what is being studied?
International researchers have described the Dunedin Study as “… probably the world’s most successful longitudinal study of a general community sample, ever.” The study followed the lives of 1037 babies born in Dunedin, New Zealand, between 1/04/1972 and 31/03/1973.
This cohort has been followed for over 40 years, making the study one of the most comprehensive and long-lasting longitudinal research projects globally. Its significance lies in the depth and breadth of data collected, covering various aspects of physical and mental health, social development, and behaviour. Thus, it provides invaluable insights into human development across the lifespan.
The original emphasis for the study was to focus on vulnerability around birth and shortly thereafter, and
“was partly motivated by the increased sophistication of birth technologies during the 1960s which had resulted in more babies surviving than ever before.” Poulton 2015
These vulnerabilities and life-course events have enabled the researchers to understand some of the long-term effects of childhood factors. The study has spawned a number of multigenerational studies involving the children of study members.
One of the unique aspects that make the Dunedin Study a benchmark is its multidisciplinary approach, combining medical, psychological, and sociological perspectives. The study’s high retention rate, with over 90% of the original participants still engaged, is exceptional and allows for robust, longitudinal analyses. Additionally, incorporating new technologies and methodologies, such as neuroimaging and genomics, has kept the study at the forefront of research innovation, continually contributing to public health policies and practices worldwide.
How good is the dataset?
Data was obtained at birth, 3, 5, 7, 9, 11, 15, 18 years of age throughout childhood, and subsequently at 21, 26, 32 and 38 years of age.
The study is widely known for its excellent, broad, and relevant data and for the inordinately high retention rate of participants, most recently 95% of living participants at the 38-year-old review.
The study coordinators (and, in my personal experience, participants) are intensely proud of this retention rate and have a strong sense of loyalty to the study.
Methods to reduce barriers to forgoing participation include simple measures like providing a creche on assessment days, flying members back to Dunedin from around the world for review or sending interviewers to meet with incarcerated participants. Additionally, the assessments are designed to be engaging and combat fatigue and boredom at each assessment point.
What meaning can be drawn from the results (so far)?
The study has generated over 1100 publications to date.
Self-Control
One of the pivotal findings from the Dunedin Study is the critical role of self-control in childhood. Research has demonstrated that children who exhibit higher levels of self-control tend to experience better health outcomes, greater financial stability, and overall higher life satisfaction in adulthood.
Self-control encompasses skills such as delaying gratification, regulating emotions, and resisting impulsive behaviours. These skills have been linked to a variety of positive life outcomes. For instance, individuals with higher self-control are less likely to engage in substance abuse and criminal behaviour, have lower rates of obesity, and generally lead healthier lifestyles. The study found that self-control is a better predictor of these outcomes than intelligence or socioeconomic status, highlighting its profound impact.
Moreover, the research indicated that self-control is not only a personal trait but can also be influenced by external factors such as parenting, education, and early intervention programs. Children who receive support and guidance in developing self-control skills tend to fare better as adults. This underscores the importance of fostering these abilities from a young age to improve long-term life outcomes.
These findings emphasize the need for policies and practices that support the development of self-control in children through family support programs, educational curricula, and community-based interventions to enhance societal health and well-being.
Health Trajectories
The Dunedin Study has provided insight into how early-life conditions affect long-term health outcomes. For instance, adverse childhood experiences (ACEs) such as poverty, abuse, and family dysfunction have been shown to significantly influence the risk of developing chronic diseases like cardiovascular conditions, diabetes, and mental health disorders. Early intervention and supportive environments may mitigate these risks and promote healthier life trajectories.
Mental Health
Findings have highlighted the profound impact of childhood experiences on adult mental health. The study revealed that mental health issues often manifest early in life and can persist into adulthood if not addressed. It has identified key risk factors, including genetic predispositions and environmental stressors, that contribute to conditions such as depression, anxiety, and antisocial behaviour. The longitudinal study allows for observing mental health patterns over time, providing valuable insights for early diagnosis and intervention strategies.
Where next?
The Dunedin Study team is currently preparing for the 45-year assessments, which will include an fMRI study of the influence of early-life adversity on particular neural hubs and their core capacities.
How is this study funded?
Initially, the study was poorly funded, as it was not conceived as such a long-running sample. In the early years, there was a heavy reliance on community participation, including local doctors donating their time to assist with data collection, the free rental of church halls, and many volunteer hours. Subsequently, there was an increase in funding, not only from the NZ government (via their Health and Research Council) and Otago University, but also significant international funding from the US National Institute of Health and the U.K. Medical Research Council.
Are there similar studies?
Several similar studies have been completed or are in progress around the world, including in Ireland, Scotland, the Netherlands, Germany, Victoria, Western Australia, and Denmark. The Australian Institute of Family Studies lists more than 20 such studies, with some study populations in the tens of thousands! Check out the full list here.
For more on the Dunedin Study, check out their site at https://dunedinstudy.otago.ac.nz/
Dunedin study is interesting. I wish to emphasis on the importance of self-control in schools. Teachers need to be encouraged to device exercises to promote self control in children.