Less recognised is the importance of the second stage of rapid brain development, early adolescence. Between the ages of eight and 14, a period sometimes called the "middle years", a person's brain goes through changes almost as radical as those in the first two years. If we want to maintain momentum from initiatives to foster development in early years, and intervene to prevent problems and set future, positive life courses, this time represents an important second chance.

Yet we know very little about what parents, or policymakers who design government programs, can do in these years to make a positive difference. We pay far more attention to very young children and older teenagers: cute babies and unruly teens gather headlines, while the middle years are ignored.

The one exception is education, where we worry about NAPLAN scores and international test rankings. In other fields such as health, material well-being, participation in society or cultural identity, children in their middle years are virtually ignored. If young people develop mental-health problems, anti-social behaviours, radicalisation and disaffection, or myriad other issues later in life, they likely had their origins in the ages 10 to 14. Unfortunately, the evidence on how or why this happens is limited.

A team of researchers from three states, led by Associate Professor Gerry Redmond of Flinders University, conducted the Australian Child Well-being Project. The report, published a year ago, made a start on understanding these middle years.

Redmond himself would be the first to agree it was only a start. Among other things, the research found that although most young people in the middle years are doing well, a significant number experience low well-being and lack opportunities most take for granted.

Almost one in five reported going hungry and were more likely to miss school as a result. Many are bullied and marginalised.

Another Australian researcher, Professor George Patton at the University of Melbourne, led the world's most comprehensive and respected study of young people aged 10 to 19, the Lancet commission on adolescent health and well-being. It concluded that the middle years have been neglected globally (it's not just Australia) and need to be better understood. This will not only reduce disease risk – remember, The Lancet is a health journal – but also enable young people to exercise creativity and innovation to "challenge the status quo, accelerate progress and advance human potential".

Australia does not take part in the international Health Behaviour in School-aged Children survey, which might give us a better handle on how we compare internationally. A feature of that survey is it goes to young people themselves, often with in-depth research on the side. By the time they reach their middle years, young people can and should have a say in what matters most for their own well-being, yet very few have opportunities to take part genuinely in public life.

A national initiative to address the lack of knowledge on the middle years will be launched on Thursday at a Families ACT event. The Middle Years Chapter will be a national network of researchers, community groups, policymakers and young people.

Supported by the Australian Research Alliance for Children and Youth, and with a national convener from the Smith Family, this new online network will allow us to gather and disseminate evidence about what works to improve the middle years. Over time, this will help Australia take up far more of these "second chances" to improve young people's lives.

Stephen Bartos is chief executive of the Australian Research Alliance for Children and Youth. stephen.bartos@aracy.org.au