Adolescence

Adolescence is a stage of human development that falls between childhood and adulthood. It begins when the body enters the early stages of physical maturity (puberty), triggered by hormones that cause physical changes and reproductive development. The end of this stage has no fixed boundary, as it depends on social and legal markers such as employment, marriage, or financial independence.

Global health organizations typically define adolescence as ages 10 to 19, though the terms 'young people' and 'youth' may have different boundaries. Definitions in statistics and policy vary by country, so comparisons between figures require attention to the definition used.

Physical changes

During puberty, the hypothalamus and pituitary gland in the brain trigger the ovaries and testes to produce hormones such as testosterone and estrogen. This leads to rapid increases in height and weight, skin changes, body hair growth, and development of reproductive organs. The timing of onset varies from person to person; genetics, nutrition, and overall health play roles.

Brain development and personality

Neuroscience research indicates that brain regions responsible for decision-making and emotion regulation—particularly the prefrontal cortex—continue to develop into the early twenties. At the same time, reward and emotion systems are highly active. This accounts in part for why adolescents sometimes take greater risks and are more influenced by peer pressure, though this is not a disorder.

Identity and society

This stage is marked by formation of a personal identity: individuals explore roles, values, and relationships. Peer relationships gain importance, though family remains foundational. Some cultures have formal initiation practices marking entry into adulthood. Secondary education and vocational training often set the course for future employment.

Health and risks

Adolescents are generally in good health, but certain issues emerge in this stage: mental health conditions such as depression and anxiety often begin during this period, road injuries, tobacco and substance use, and reproductive health concerns. Health education, access to age-appropriate services, and family support are discussed as ways to reduce these risks.