Wednesday, December 29, 2010

Part 2 of 3: Stress and the Adolescent Brain

                 Research is indicating that the adolescent brain is particularly sensitive to the effects of high glucocorticoid levels and therefore to stress as well.  During the teenage years, there appear to be high levels of glucocorticoid mRNA (a chemical that comes from DNA and encodes a type of blueprint for the creation of a specific type of protein) in the prefrontal cortex, which is an area that also undergoes development during this time.  This suggests that the functions that this part of the brain is responsible for, mainly cognition (reasoning, thinking, planning, sequencing, judgement, etc.) and emotion, are heavily affected by glucocorticoids and therefore by stress.  Many forms of psychopathology like depression and anxiety show up in adolescence, often following a period of particularly severe stress.  So all of this information is basically another way of saying that teenagers' emotions and decision-making abilities are prone to fluctuate according to any tiny little outside event…which we probably didn't need a neuroscientist to tell us, but now we know why!
                Interestingly, although the prefrontal cortex is greatly affected by stress, it seems that the hippocampus is spared in this period.  This is likely because the hippocampus finishes developing around 2 years of age.  Children who suffered abuse through late childhood and early adolescence did not show a decrease in hippocampal volume in adolescence, although interestingly they do show this decrease later on in adulthood.  More to come in my next post about what happens to the stressed brain as we age!

Adapted from "Effects of Stress Throughout the Lifespan on the Brain, Behaviour and Cognition" by Sonia Lupien et al. and inspired by Wayne Brake's Neuropharmacology course at Concordia University.  

Cristina McHenry 
Concordia University

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