A huge population of the world, above 1.75 billion, is young (between 10-24 yrs).

Adolescence is defined by WHO as the age group between 10-19 years. Youth is defined as the age range between 15 and 24 years, and young people between 10 and 24 years. There are an estimated 1.2 billion adolescents - one in every five individuals - in the world today. This is the largest number of adolescents in the history of mankind. About 85% of them live in developing countries and the remainder in the industrialized world.

Adolescents have specific health and development needs, and many face challenges that hinder their well-being, including poverty, a lack of access to health information and services, and unsafe environments.

The second decade of life is a period of major physical and psychological change, as well as great changes in social interactions and relationships. Adolescence is a period of joy for many and a happy memory into adulthood. However, many adolescents are not so fortunate. Although most adolescents are healthy and grow smoothly into adulthood many are vulnerable and face a lot of adversities.

Physical growth is accompanied by sexual maturation, often leading to intimate relationships.

The individual’s capacity for abstract and critical thought develops, along with a heightened sense of self-awareness and emotional independence.

As the attitudes, values and behaviors that determine the young person’s future begin to take shape, society expects the adolescent to assume greater personal responsibility. This process is marked by increased exposure and experimentation. The risks inherent in “first time” behaviors – especially the use of tobacco, alcohol and other drugs, along with sexual activity – make the second decade of life a period of increasing vulnerability.

Some of the health problems faced by adolescents affect them immediately e.g. death by suicide or interpersonal violence, or an unsafe abortion.

Others show a long term adverse effect e.g. HIV, cancers, tobacco use etc

Adolescents can be innocent victims of social and economic disadvantages of their parents. Virtually all governments have confirmed their right to have these needs fulfilled, with the ratification of the Convention on the Rights of the Child.

Diversity

There is enormous diversity among adolescents, regardless of where they happen to live. At the lower end of the age range, they consist of girls and boys, most of whom are not yet sexually active. At the upper end, they consist of physically mature young women and men, most of whom are sexually active and in many cases have children of their own.

There is also great diversity among adolescents of the same age, depending on the individual’s gender, level of physical, psychological and social development, and on factors in the individual’s immediate environment and within the culture of the wider society.

Mortality rates

Adolescents are generally thought to be healthy. By the second decade of life, they have survived the diseases of early childhood, and the health problems associated with ageing are still many years away.

Death seems so far removed as to be almost unthinkable. Yet many adolescents do die prematurely. Every year, an estimated 1.4 million young men and women between the ages of 10 and 19 lose their lives - mostly through accidents, suicide, violence, pregnancy related complications and illnesses that are either preventable or treatable.

Millions more suffer from chronic conditions that may well endure a lifetime. Even more importantly, most mortality in adulthood has its roots in the adolescent period.

WHO estimates that 70% of premature deaths among adults are largely due to behaviors initiated during adolescence. Tobacco use, for example, typically starts before the age of 20, and frequently leads to premature death later in life. Another good example is HIV infection, which is often contracted in adolescence or early adulthood, and will require lifetime treatment or lead to AIDS some years later.

 
Major health issues

Mental Health

20% suffer from some form of mental health problems.

Substance use and misuse

Tobacco and alcohol consumption are gateway drugs that most often start in adolescence and may lead to more hard core drugs and addiction that lasts into adulthood.

Life style diseases

Nearly two thirds of premature deaths and one third of the total disease burden in adults are associated with conditions or behaviors that began in youth, including tobacco use, lack of physical activity, unprotected sex or exposure to violence. Promoting healthy practices and empowering youth will ensure longer, more productive lives for many.

Violence & Unintentional Injuries

Among 15-19 year olds, suicide is the second leading cause of death, followed by violence in the community and family.

Nutrition

Adolescents in the developing world show a high incidence of malnutrition and anemia and those from the developed world show a rising incidence of obesity.

Sexual and Reproductive health

Experimentation is a characteristic of this age. Planned and protected sex will decrease the incidence of unwanted teenage pregnancies and STDS. Sexual education is a must at school.

HIV/AIDS

Young people aged 15-24 accounted for an estimated 45% of new HIV infections worldwide in 2007.

Early marriage and pregnancy both in and out of wedlock

About 16 million girls aged 15 to 19, give birth every year (roughly 11% of all births worldwide). Septic abortions are an important cause of mortality. In the developing world, teenage pregnancies are associated with a four times higher mortality than that of mothers of the 19-24 age group. Babies of teenage mothers also have a higher incidence of preterm and LBW and other morbidities.
Socio-economic deprivation is both a cause and a consequence of adolescent pregnancy.


Reference WHO fact sheets on Adolescent Health