Adolescent development: physical and neurological
As an individual transforms from a child to an adult in the period known as adolescence, they experience great physical, neurological and psychological changes. In this step we focus on the physical and neurological changes that occur during puberty. The various areas of development (physical, neurological, emotional and social) interact closely with one another, and a physical change may trigger a positive or negative emotional response in the adolescent.
Puberty is a gradual process and begins with an increase in hormone production that brings about a range of physical changes. These include rapid growth in an individual’s height and weight and the emergence of secondary sexual characteristics as a child moves towards an adult state. For girls these include:
- the onset of ovulation and menstruation
- development of breasts
- growth of body, underarm and pubic hair.
- a deeper voice
- erections and wet dreams
- growth of body, facial, underarm and pubic hair.
The speed of these visible changes, coupled with a difference in hormone levels, can lead some adolescents to worry about their appearance. There is a wide range of what can be considered ‘normal’ development, as changes can occur at different rates depending on the individual. Less visible are the internal physiological, cognitive, and emotional changes that occur during puberty.
A human brain is not fully developed when a person reaches puberty, but although the brain doesn’t grow much in absolute size during adolescence, it does change rapidly. Neurons that are not being used are ‘pruned’, while others that are actively used grow a fatty sheath (are ‘myelinated’) so that they can conduct very rapidly.
The limbic system and amygdala, which are situated deep inside the brain, are very important for emotions and ‘rewards’. These develop relatively early, whereas the frontal lobe of the brain, which is situated just behind the forehead, is particularly important for executive functioning, which includes planning ahead, reasoning, considered decision-making and self-discipline. It is one of the last areas to mature, and is not fully mature until at least 25 years of age. This may explain why adolescents and young people tend to take risks and are prone to ‘hot cognitions’, making decisions rooted in emotions and experiences rather than logical reasoning.
Normal, healthy development is uneven
Changes on these multiple fronts do not always happen in sync. For example, an adolescent girl may look physically mature, but psychologically she is still developing. Her appearance can lead people to believe and expect that she has mature thinking patterns or can manage her emotions, and this may not be the case. Conversely, another girl who looks physically immature may have more mature ways of thinking.
© London School of Hygiene & Tropical Medicine