The brain continues to change and mature throughout adolescence. An adolescent’s brain reaches its adult weight by about age fourteen, partly because of increased myelination.
As myelination and pruning continue during the teen years, adolescents become more capable of insight, judgment, inhibition, reasoning, and social conscience. Increased activity in the frontal lobe enables the adolescent to begin analyzing or interrelating several concepts at once.
Myelination of the frontal lobe is not complete until very late in adolescence. Some researchers estimate that frontal-lobe development continues until age 25 to 30. The regions in the frontal lobe responsible for judgment, planning, assessing risks, and decision-making are the last areas to finish developing.
Repeated experiences create complex networks of synaptic connections. Connections strengthened through regular use to become stronger and more complex. Selective pruning of non-essential connections also continues during adolescence. Most pruning takes place between ages ten and sixteen. The pruning process enables the brain to operate more efficiently and provides room for networks of essential connections to expand.
Synapse formation continues in adolescence, even as pruning is ongoing. The remaining dendrites continue to branch, grow, and form new synapses in response to new experiences. Continued social, emotional, and cognitive development in adolescence is due, in part, to this ongoing growth in the brain.