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Skip to 0 minutes and 13 secondsBEVERLEY JANE FERGUSON: Adolescence is a crucial period of human development. In fact, it's a time of rapid development, second only to early childhood. There are so many things that are going on during that 10 year period of time. So WHO talks about adolescence as being from 10 to 19 years. Sometimes, we also talk about youth as being-- the UN in particular talks about youths as being-- the period between 15 and 24. We try to lump them together and talk about young people, which is then 10 to 29. But the critical developmental times are 10 to 19, and we use those two five year age periods because many countries collect, and collate and disaggregate data in five year age span.

Skip to 1 minute and 9 secondsSo often, people will talk about very young adolescents which are 10 to 14, and 15 to 19-year-olds, which are older adolescents. What's special about being an adolescent again is the period of development, the rapid development that's going on. Social, biological, emotional, all happening, often at the same time, very rapidly, and often inconsistently. It provides great opportunities for the individual to change and to be perceiving things a different way. So in particular, the way in which they're thinking, the body is changing, and of course, that's how the social world thinks mostly of that or the physical changes that are going on.

Skip to 1 minute and 58 secondsSo it's important for health because it really is the fundamental notion that people need to think about when they're thinking of how to prevent and respond to health problems is rooted in the way in which adolescents are developing. So for health practitioners, and parents, and adolescents themselves to have a clear idea of what's happening to them at an individual level is really very critical. One of the things that's happening in terms of their development is how they interact with the environment. The environment, the social environment, their family around them, first and foremost, but secondarily then, their peers, teachers, community members, key leaders, and going out. We often think of it in terms of concentric circles.

Skip to 2 minutes and 44 secondsThe adolescents are starting to have more interaction with the social environment. Of course, in some countries, this is culturally restricted, particularly among girls, but they still are much more aware of what's going on the social world, and what's going on in their social world is impacting on them. So there's quite a relationship between the two of them, and this is very critical. It's very critical for all of human development, in fact. And we know that what's happening in the environment, the social environment in particular, a good example, the best example, I think is violence, a violent environment at the family level.

Skip to 3 minutes and 23 secondsWe know that this influences brain development and how brain development is occurring during adolescence, which impacts on their cognition, their ability to learn, their emotional reactivity, and then subsequently has effects on their mental health, drug use, which then relates to often violent behaviours and sexual behaviour. So all of those kinds of things which are rooted in the environment, and interventions which then also need to be targeted at the environment of the adolescent as well as on the individual themselves. So those are the really, really critical aspects. In terms of WHO, we've been-- we at WHO have been active in an adolescent health really for over 25 years.

Skip to 4 minutes and 13 secondsAnd increasingly, I think the organisation has understood that adolescence has a central place in many, many programmes, not just in the programme which I work. So for example, the understanding, the increasing understanding of the importance of health across the life course, that interventions made at one point in time have very important effects at another point in time. The increasing focus on non-communicable conditions, which of course now outranks, in terms of mortality, non-communicable diseases-- communicable diseases. And the very important recognition that many of the behaviours that underlie these conditions often start during adolescence. So tobacco use, alcohol use, adequate or inadequate physical activity and diet, are four of the key risk factors that underline the whole NCD agenda.

Skip to 5 minutes and 16 secondsThese are all adolescent issues. I think also the more recent focus on universal health coverage. There's an increasing understanding that adolescents are in fact not well served by health services, that they are underserved, and that it's not only a question of human rights, where the human rights lobby would certainly be saying that. But also-- they are being missed out. So that is a perspective that gained some impact at WHO. And finally, I think that within WHO, within all the health programmes, there's generally an understanding that one has to intervene on the individual level. But one critically has to intervene at the environmental level.

Skip to 6 minutes and 4 secondsWHO's full public health agenda takes on all of these things, and I think that there's an increasing understanding that all of this is relevant to improve and promote the health of adolescents.

What do we mean by adolescents and young people?

Adolescence is a crucial period of rapid development that encompasses significant changes in a person’s life, perhaps second only to that experienced in early childhood. In this step Dr Beverly Jane Ferguson introduces how adolescents and young people are defined, what’s special about this period of life, and how adolescence impacts someone’s health in adulthood.


The World Health Organization (WHO) defines adolescence as the period in human growth and development that occurs after childhood and before adulthood. Specific definitions are as follows:

  • Adolescents: 10-19 years old
    (Young adolescents: 10-14 years old)
    (Older adolescents: 15-19 years old)
  • Youth: 15-24 years old
  • Young people: 10-24 years old

A time of change

The importance of the health of adolescents far exceeds immediate mortality and morbidity: habits formed and decisions made at this stage of life can have a profound effect on an individual’s health throughout the lifecycle. It’s therefore fundamental to understand what is happening to adolescents during their development when we think about how to prevent and respond to health problems.

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This video is from the free online course:

Improving the Health of Women, Children and Adolescents: from Evidence to Action

London School of Hygiene & Tropical Medicine