What are the effects of stress & adversity on the brain that affect well-being? A recent review by Davidson & McEwen in Nature Neuroscience (“Social influences on neuroplasticity: stress and interventions to promote well-being”) explores this question. One interesting aspect about research on the relationship between the brain and “happiness” or “well-being” is how we operationally define these constructs. Most of us “know” what “happiness” is - or do we? What about well-being? Interestingly, Davidson & McEwen do not define well-being in this review; they assume we all agree on what it is.
Assuming that we all agree on what well-being is, the review summarizes animal and human research on the effects of stress on the brain and on social/emotional functioning. We know that chronic stress reduces dendritic branching in the medial prefrontal cortex and hippocampus, while it increases branching in orbitofrontal cortex and amygdala. These regions are important for emotional and social behavior, and Davidson & McEwen propose that they are important for well-being. The effects they summarize on dendritic branching in these regions are reversible, especially in children, so perhaps therapies that lead to a better sense of well-being are, at least in part, acting through these brain regions/circuits.
Early life stress is a particularly extraordinary example of how experience influences brain structure and function in ways that can have devastating effects on how a child is able to function in the world. But the hopeful message of this review is that, even though the horrible stress of child abuse has detrimental effects on a child’s brain, these effects should be at least partly reversible, based on animal research. The positive effects found following intervention programs that address emotional and social functioning in school-aged children reflect changes in brain structure and function.