Executive functions from infancy into early childhood: Measuring robust cognitive and neural markers of development and risk

This research aims to understand more about how executive functions develop in very early childhood, between approximately 9 months and 2.5 years of age. Executive functions refer to a set of skills and abilities that allow us to solve problems, plan and organise our lives, make decisions, and cope when we have to do many different things at the same time. Some of these abilities involve keeping important things in memory while solving a problem - for example doing mental arithmetic or reading a set of instructions. Other executive functions help us stop habits and overcome temptations when these are not good for us. In a way, executive functions allow us to have some control over our lives, instead of being completely ruled by habits and circumstances.

Because executive functions are so important for being able to live a successful life, it is not surprising that children who have problems with executive functions also tend to struggle in other important areas, such as in school and in social situations. Children who have a diagnosis of developmental disorders, such as attention-deficit/hyperactivity disorder (ADHD) and autism spectrum disorder (ASD), also often have poorer executive functions.

Unsurprisingly, young children's executive functions are far from perfect - they struggle to keep things in memory, to plan for themselves, and to resist temptation. Children improve very fast in these skills between 3 and 5 years of age and continue to improve right up until adulthood. However, we know very little about how children get their very first executive function abilities during the first 2 years of life. Of course their skills at this young age are likely to be limited, but research suggests that they are in fact present. One problem, though, is that it is quite difficult to measure executive functions in babies and toddlers. We cannot do this the usual way because very young children are limited in their motor and language skills - we cannot simply tell them what to do. Nevertheless, we can develop alternative ways of measuring these skills. For example, developmental psychologists often look at what babies prefer to look at in specially designed videos and get toddlers to play specially programmed games on a computer in order to figure out how young children understand and act on the world around them. In the present research, such videos and interactive games (called 'tasks') will be used to extract measures of even these very young children's executive function abilities.

The present research aims to design more and better measures of executive functions in babies and toddlers. The tasks used to measure executive functions will be designed so they are as similar as possible for different age groups, but also get harder as children grow older. I will also use measures of brain activity to see how the brain develops alongside children's executive functions. Once I know that the tasks work well and measure what they are supposed to measure, I will study a large group of approximately 200 children from 9 months until 2.5 years of age. Because the same children will be followed as they grow older, I will be able to see if some children start to develop problems with executive functions and at what point in time this happens. This is important because if we know what the signs are that some children are developing problems, then we can start working on finding ways of helping these children. When children develop specific disorders, such as ADHD and ASD, they are often not diagnosed before they are 3-5 years old. With this new research we may one day be able to diagnose and help these children at an earlier point.

Executive functions (EFs) are a set of cognitive abilities that allow us to guide our behaviour and make adaptive decisions. They provide us with the ability to control our thoughts and actions, solve problems, and multi-task. Without EFs we would be largely controlled by immediate circumstances and habitual responses.

EFs are particularly challenged in young children, who struggle to maintain and manipulate information in working memory, inhibit strong response tendencies and shift between different perspectives and actions. They are also compromised in children with developmental disorders and those with academic and social difficulties. Between 3 and 5 years of age EF skills improve rapidly. However, little is known about EFs before this age. This is due to the lack of psychometrically adequate EF tasks for this age group.

With this proposal, I aim to push down the boundary for successful EF assessment by designing a new task battery specifically for 9- to 30-month-old children. Tasks will be structurally similar across age, ensuring that they measure the same construct at different time points. Once tasks have been psychometrically validated, I plan to undertake a longitudinal study of 200 children. Children will be assessed on the new battery along with concurrent measures of brain activity. This will provide important knowledge on the very earliest development of EFs, the biological substrate of this development, and individual trajectories. Outcomes in terms of behaviour problems and early signs of attention-deficit/hyperactivity disorder will be assessed so that potentially problematic EF trajectories can be identified earlier than presently possible. This is an important step towards improved diagnosis and intervention for children at risk of poor EFs and associated developmental disorders. The task battery will be made available to other researchers and clinicians, providing a new tool for others to use in an area where none currently exists.

The most immediate beneficiaries of the research will be researchers interested in executive functions. Researchers in related fields are also likely to find the research of interest and use. Academic beneficiaries will benefit from the research in terms of increased knowledge and new tools as soon as the first results are disseminated. These impacts are likely to be realised within a few years of the initiation of the research.

Staff working on the project will benefit in terms of training and development of high-level research and technical skills.

In the longer term, when the new EF task battery has been fully developed and validated, clinicians and educationalists will also benefit. They will have a new measurement instrument available to help them assess EFs earlier than previously possible. EFs are impaired in many neurodevelopmental disorders. For this reason, making the task battery and its associated research knowledge base available to practitioners has clear impacts in terms of enhancing the quality of life and improving mental health in children. It will provide an additional diagnostic tool that can help detect developmental problems earlier during childhood, paving the way for early intervention and support for these children. The task battery may also be used directly in intervention research as a marker of improvement in EFs and associated abilities as an outcome of specific interventions. The time-scale for these clinical and educational benefits is longer because the task battery cannot be made publically available as a standardised tool before it has been fully validated and all the key results published. I expect this to take approximately 5 years in terms of clinical use, and longer in terms of using the battery for intervention research (the latter will require an additional programme of 3-4 years' research upon the completion of battery development and validation).

In a wider perspective, increasing knowledge about the earliest development of EFs, and providing a new tool for their assessment, may in the long term have important policy and societal implications, especially when the battery is eventually used for intervention and intervention research with children who have or are at risk of developmental disorders. Research on EF interventions in pre-schoolers has shown that it is possible to roll out highly beneficial, but nevertheless simple and cost-effective, programmes of EF training in children at risk (Diamond et al., 2007). A particular strength of the proposed research is that it may eventually allow such intervention or educational programmes at an earlier age before problems are too severe, thus leading to better and more lasting benefits for children at risk.

Finally, I believe that the research will be of interest to the general public. Although a general audience my not know the term 'executive functions' most people will have a tacit understanding of the concepts involved (such as the ability to plan and organise one's life, multi-task, and keep things in memory while doing something else) and may find it interesting to learn about how these abilities develop. Furthermore, as detailed in the Case for Support, one the main aims of the research is being able to detect developmental problems and help children with such problems at the earliest possible point. Developmental disorders are common, affecting about 1 in 6 children (Boyle et al., 2011), meaning that this is something that affects many families in the UK and abroad. The benefits described above for clinicians, educationalists and policy-makers will also apply to these families once the research has been brought to its full potential.

References:

Boyle, C. A. et al. Trends in the prevalence of developmental disabilities in US children, 1997-2008. Pediatrics 127, 1034-1042 (2011).
Diamond, A., Barnett, W. S., Thomas, J. & Munro, S. Preschool program improves cognitive control. Science 318, 1387-1388 (2007).