when does the brain fully develop

The brain is generally considered to be fully developed in the mid-to-late 20s, with the prefrontal cortex being the last part to mature. The prefrontal cortex, which is responsible for higher-level functions like planning, self- control, judgment, and decision-making, typically finishes developing around age 25. This extended development timeline helps explain why teenagers and young adults may struggle with emotional regulation, risk assessment, and long-term thinking. Although brain size is mostly complete by age 5, brain maturity—meaning the wiring, organization, and complex functions—continues through adolescence and into early adulthood. Processes such as synaptic pruning (removal of unused neural connections) and myelination (insulation of nerve fibers to speed up communication) continue until around age 25, especially in the prefrontal cortex. Scientific consensus shows that this brain development and maturation process supports cognitive, emotional, and behavioral maturation well into the mid-20s, not fully completing until around age 25 to 30.