Registered Nurses' Association of Ontario

Teen Brain Development

The brain matures from “back” to “front:”

  • Myelinzation of white matter occurs from 5 to 20 years of age.

 Adolescent decision-making behaviours are more influenced by the amygdala in the limbic system than the prefrontal cortex:

  • Decision-making is influenced by emotional and gut responses.
  • This is the “reactive” part vs. the “thinking” part of the brain.

The pre-frontal cortex (the brain’s “CEO”) develops last (up to 25 years of age):

  • It is responsible for planning, strategizing, judgment, impulse control and regulation of emotions.
  • The region demonstrates a growth spurt at 11 or 12 years of age, then “prunes” away unused pathways and “hardwires” what is being used.
  • The result is increased response to emotional reward and less engagement in cognitive control.


  • To promote the healthy development of all youth, attention must also be given to the strengths of and challenges faced by immigrant youth and their families.
  • A comprehensive, inter-sectoral approach – including the participation of health, social services, education systems and resettlement services – is required to facilitate the settlement of newcomer youth and their families in Canada.
Women and Children
Enhancing Healthy Adolescent Development
Background Information