Eye rolling, rule breaking, back-talking, excessive sass — all hallmarks of the teenage years. Often times, adolescence is discussed and accepted as a tumultuous period of chaos.

This negative connotation poses problems because of the importance of adolescence for brain development; much of the reason why teenagers act the way they do is directly related to the fact that the frontal cortex undergoes significant maturation. The brain matures sequentially, with the evolutionarily youngest region, the frontal cortex, fully developing last.

The adolescent frontal cortex undergoes many changes that show it is becoming more efficient and contribute to shaping who we are (Sapolsky, 2017). Gray matter volume in the brain reduces, signifying a reduction of dendrites and more generally the number of neurons. The reduction in gray matter is indicative of neuronal pruning and illustrates the brain is getting rid of unneeded neurons. This is essentially like going through your closet and getting rid of the clothes you think you might wear once, but probably won’t. The frontal cortex additionally gains white matter volume, indicating more myelination of neurons. This speeds up neural signals, facilitates better communication between neurons in the brain, and strengthens connections between the frontal cortex and other brain regions to create coordinated neural circuits. These two brain changes are fundamental in helping adolescents improve in a variety of cognitive domains, from working memory to executive functioning to reappraisal of situations.

However, the brain is not immune to environmental impacts and “every hiccup of experience has an effect, albeit usually a minuscule one, on [the] brain” (Sapolsky, 2017). Neuronal pruning is one of the brain changes that is influenced by environment and context. This has many negative consequences and can produce lifelong effects on cognitive functioning. Stress during childhood and adolescence is particularly detrimental to normal brain development. Worries about socioeconomic status (SES) can be especially stress-provoking. Mediated by education attainment and income level, low SES hurts cognitive and socio-emotional development by reducing amygdala, hippocampus and frontal cortex area volumes (Brito & Noble, 2014). A low socioeconomic status creates a heightened level of stress; during high stress, some normal bodily functions are put on hold. When you are in fight or flight mode, your body is not concerned about digesting food or pruning unnecessary neurons, and instead channels its energy toward things like a quickened heart rate and muscle tensing (Romeo, 2013).

Furthermore, living in an impoverished country and experiencing malnutrition during childhood and adolescence has been linked to reduced brain development and poorer cognitive skills as an adult (Sapolsky, 2017). Thus, it is obvious and disheartening that living with chronic high stress has long-term implications.

Another influential part of adolescence is your parents and home environment. It seems like most teenager butt heads with their parents, but parental neglect and abuse are especially damaging. Orphaned children placed in institutions show reduced emotional processing (Nelson et al., 2013) and a general reduction in brain activation over the frontal and temporal lobes, as shown by EEG analysis (Marshall et al., 2004), which can likely be attributed to disrupted brain development.

Neglect when growing up also changes how the HPA axis activates in response to stress; those who experienced neglect and abuse as a child react differently to stressors than those raised in a nurturing environment (NSCDC, 2012). And finally, experiencing high stress during adolescence increases the likelihood that the individual will develop depression and anxiety disorders (Romeo & McEwen, 2007).

As you can see, the environment plays a huge role in shaping who we are. This is especially pronounced during childhood and adolescence, where experiencing adversity can change brain architecture in developing regions and create a host of behavioral, emotional, and social problems. It would be beneficial to take this information into account to change the institutions that have a great impact in teenagers’ lives, such as the education system and social media.

References

Brito, N. H. & Noble, K. G. (2014). Socioeconomic status and structural brain development. Front. Neurosci. 8 (276). doi:10.3389/fnins.2014.00276.

Center on the Developing Child (2007). The Impact of Early Adversity on Child Development (InBrief). Retrieved from www.developingchild.harvard.edu.

National Scientific Council on the Developing Child (NSCDC). (2012). The Science of Neglect: The Persistent Absence of Responsive Care Disrupts the Developing Brain: Working Paper 12. http://www.developingchild.harvard.edu.

Nelson, C. A., Westerlund, A., McDermott, J. M., Zeanah, C. H., & Fox, N. A. (2013). Emotion recognition following early psychosocial deprivation. Development and psychopathology, 25(2), 517-25. doi: 10.1017/S0954579412001216.

Marshall, P. J., Fox, N. A., Bucharest Early Intervention Project Core Group. (2004). A comparison of the electroencephalogram between institutionalized and community children in Romania. Journal of Cognitive Neuroscience, 16(8): 1327-1338.

Romeo, R. D. (2013). The teenage brain: The stress response and the adolescent brain. Current Directions in Psychological Science, 22(2): 140-145. https://doi.org/10.1177/0963721413475445.

Romeo, R. D. & McEwen, B. S. (2007). Stress and the adolescent brain. Annals of the New York Academy of Sciences, 1094: 202-214. doi:10.1196/annals.1376.022.

Sapolsky, R. M. (2017). Behave: The biology of humans at our best and worst. New York, NY: Penguin Books.