Both studies conducted on animals and humans conclusively reveal that long-term and severe stress have a harmful effect upon the brain. If the brain is harmed in such a manner, an individual’s chances of developing mental illness is considerably increased. However, there is also good news : if the brain incurs such damage, this is frequently reversible (click here to read an article I previously wrote relating to this phenomenon).
Because the brain is still developing during childhood and adolescence, and its physical structure more ‘plastic’ (ie more susceptible to being changed) than in adulthood,it is particularly vulnerable to the adverse effects of stress during these periods (it is most vulnerable of all during infancy which is why these earliest years are of such critical importance).
Above. The grey circle on the second diagram shows the part of the brain in which stress can cause executive functioning to partially shut down. The red circle shows the part of the brain in which stress activates the fear/ ‘fight or flight response.’
How severe and protracted the experience of stress during childhood will influence the degree of damage the developing brain suffers. The stressors themselves are varied ; they include poverty, neglect and abuse, or, indeed, a combination of these.
ANIMAL STUDIES DEMONSTRATING THE EFFECTS OF STRESS UPON THE BRAIN :
There have been literally hundreds of animal studies showing that stress can have a harmful effect upon the brain. For example, research on rats placed in high stress environments shows that both the structure and function of their hippocampus (the human brain, too, has a hippocampus ; the structure is involved in the stress response) is adversely affected.
Furthermore, similar studies show that when rats are deprived of proper maternal care their hippocampus is similarly damaged.
Other studies, also involving rats, show that when they are placed in impoverished environments (ie environments in which there is no stimulation), again there is a harmful effect on the structure and functioning of their brains.
THE GOOD NEWS – REVERSIBILITY :
However, the good news is that these adverse effects on the rats’ brains, caused by the various stressors described above, are, at least in part, reversible. This reversing process can be achieved by transferring the rats from an impoverished environment to a stimuli rich environment, or transferring the rats deprived of maternal care into the care of a female rat that licks and grooms them, for example.
RESEARCH ON HUMANS :
It appears we can extrapolate from the findings of such animal studies described above and apply them to humans. Indeed, human studies have demonstrated that children who grow up in poverty, and have to cope with the stress of having little mental stimulation, can also incur harm to the structure and functioning of their brains, in particular, in relation to their prefrontal cortex and hippocampus.
Furthermore, it has been found that those children who are exposed to significant abuse will tend to have a lower brain volume than their peers who did not experience such abuse.
However, in humans, too, such damage appears to be reversible (click here to read my article related to this).
It appears that, in humans, different parts of the brain are particularly susceptible to damage at different stages of the young person’s life. For example :
Between the ages of 3 years old and 5 years : the hippocampus appears to be particularly vulnerable.
Between the ages of 14 and 16 years : the prefrontal cortex appears to be particularly vulnerable.
EARLY INTERVENTION :
It is also now known that if a child is potentially being damaged by a highly stressful environment, the earlier intervention takes place to alleviate the stress, the more likely it is that any harm that has already been done to the brain can be reversed.
DELAYED EFFECTS :
Research has also found that such damage incurred by the human brain as described above may well not be immediately apparent. Indeed, it can take many years for the adverse effects to reveal themselves.
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David Hosier BSc Hons; MSc; PGDE(FAHE).