Brain development during adolescence: neuroscientific insights into this developmental period

Abstract

Background: Adolescence is the phase of life between late childhood and adulthood. Typically, adolescents seek diversion, new experiences, and strong emotions, sometimes putting their health at serious risk. In Germany, for example, 62% of all deaths among persons aged 15 to 20 are due to traumatic injuries. Neuroscientific explanations have been proposed for typical adolescent behavior; with these explanations in mind, one can derive appropriate ways of dealing with adolescents.

Method: We selectively review pertinent articles retrieved from the PubMed database about the structural and functional development of the brain in adolescence.

Results: New findings in developmental psychology and neuroscience reveal that a fundamental reorganization of the brain takes place in adolescence. In postnatal brain development, the maximum density of gray matter is reached first in the primary sensorimotor cortex, and the prefrontal cortex matures last. Subcortical brain areas, especially the limbic system and the reward system, develop earlier, so that there is an imbalance during adolescence between the more mature subcortical areas and less mature prefrontal areas. This may account for typical adolescent behavior patterns, including risk-taking.

Conclusion: The high plasticity of the adolescent brain permits environmental influences to exert particularly strong effects on cortical circuitry. While this makes intellectual and emotional development possible, it also opens the door to potentially harmful influences.

Figure 1

The development of the prefrontal cortex is protracted in man compared to other primates. The Figure shows the synaptic density per 100 µm² in the prefrontal cortex as a function of age in man (red), chimpanzees (blue), and rhesus macaques (olive green) (error bar = 95% confidence interval). From (40) Lui et al.: Extension of cortical synaptic development distinguishes humans from chimpanzees and macaques. Genome Research 2012; 22: 611–22. Reprinted with the kind permission of Cold Spring Harbor Laboratory Press, New York

Figure 2

Development of the white matter and gray matter of the frontal cortex over a human lifetime; separate curves for each sex. From (7) Giedd JN, et al.: Brain development during childhood and adolescence: a longitudinal MRI study. Nature Neuroscience 1999; 2: 861–3. Reprinted with the kind permission of Nature Publishing Group, London

Figure 3

Nonlinear maturation processes of subcortical and prefrontal brain areas lead to an imbalance of neural networks in adolescence. Modified from (12) Casey BJ, Jones RM, Hare TA: The adolescent brain. Annals of the New York Academy of Sciences 2008; 1124: 111–26. Reprinted with the kind permission of John Wiley and Sons