The prefrontal cortex, responsible for planning, impulse control, and social behavior, is famously the last part of the brain to fully mature. According to research from the National Institute of Mental Health (part of the National Institutes of Health, or NIH), this region continues developing well into one’s twenties, shaping decision-making and self-regulation along the way.
Why does the prefrontal cortex develop so late?
One reason for this late development lies in the brain’s growth pattern. Research shows that the brain matures in a back-to-front sequence, meaning the prefrontal cortex responsible for higher order thinking, decision making, and impulse control is one of the last regions to fully develop. This slow maturation process is linked to the formation of white matter, which plays a crucial role in brain connectivity. White matter consists of myelinated axons that facilitate faster and more efficient communication between different brain regions. As myelin accumulates with age, particularly in the frontal lobe, cognitive functions such as reasoning, self-regulation, and long-term planning improve. Gray matter, on the other hand, consists of the cell bodies of neurons and the dendrites that receive signals from stimuli and other neurons.
A study published in Nature Neuroscience highlights that during adolescence, gray matter density decreases due to synaptic pruning, while white matter increases, improving connectivity and efficiency. Synaptic pruning is a natural process where weaker or unused neural connections are eliminated, allowing the brain to become more specialized and efficient. This refinement, alongside increasing white matter, strengthens communication between different brain regions, enabling more coordinated and complex cognitive functions
The prefrontal cortex’s role extends beyond decision-making, as it also plays a key part in emotional regulation and risk assessment. Vanderbilt University researchers have examined how variations in prefrontal cortex activity influence anxiety and social behavior. A study led by Jennifer Blackford, Ph.D., an associate professor of Psychiatry and Behavioral Sciences at Vanderbilt, found that when this brain region is either underdeveloped or overactive, children may face a heightened risk of anxiety. This delayed development also has real world consequences for older individuals; for example, mortality rates among 15- to 24-year-olds are more than triple those of middle school children. Since the prefrontal cortex is still maturing during this period, young adults are more prone to impulsive decision making and risk taking behaviors that can lead to dangerous outcomes.
The inner workings of the brain
Through synaptic pruning, brain development follows a “use it or lose it” model, shaping how neural connections are strengthened or discarded. Harvard’s Center on the Developing Child explains that frequently used neural pathways become stronger, while unused ones fade away. This explains why skills learned early in life, such as playing an instrument, can become difficult to reacquire if abandoned for too long. The brain essentially prunes what it deems unnecessary.
Understanding the prefrontal cortex’s gradual development helps explain everything from teenage angst to the questionable fashion choices of your high school years. Encouraging activities like problem-solving exercises, mindfulness, and structured decision-making can support this crucial stage of brain growth. Next time you make a baffling decision, just remember: the prefrontal cortex is still getting its act together.
References
Center on the Developing Child at Harvard University. What is executive function and how does it relate to child development? Harvard University. https://developingchild.harvard.edu/resources/infographics/what-is-executive-function-and-how-does-it-relate-to-child-development/
Diamond, A. (2013). Executive functions. Annual Review of Psychology, 64, 135–168. https://doi.org/10.1146/annurev-psych-113011-143750
National Institute of Mental Health. The teen brain: 7 things to know. U.S. Department of Health and Human Services. https://www.nimh.nih.gov/health/publications/the-teen-brain-7-things-to-know
Tottenham, N., & Galván, A. (2016). Stress and the adolescent brain: Amygdala-prefrontal cortex circuitry and ventral striatum as developmental targets. Nature Neuroscience, 19(10), 1284–1291. https://doi.org/10.1038/nn.3788
Vanderbilt University Medical Center. (2016, October 13). Study may help predict anxiety risk in children. VUMC Reporter. https://news.vumc.org/2016/10/13/study-may-help-predict-anxiety-risk-in-children/#
