As humans, it is in our nature to crave other peoples’ attention. The level of affection we receive is critical to our development and psyche throughout the course of our lives. Its significance is further heightened in childhood, as we are most vulnerable at this stage. This raises a question: can an adverse upbringing environment alter a child’s brain landscape?
A recent study, led by Drs. Sonia Lupien and Jean Séguin from the Université de Montréal alongside McGill colleagues, found that children of depressed mothers have a larger amygdala, a structure vital for emotion regulation and danger level assessment of an environment. Researchers speculate that children raised in an environment where the support – especially that needed to help assess the environment – is insufficient may be better at threat recognition than those raised in more supportive environments.
For the study, 38 children whose mothers suffered from maternal depressive symptomatology (MDS) were selected from the Quebec Longitudinal Study of Child Development. The MDS scale measured depressed mood, positive affect, and psychomotor retardation. MDS scores of the mothers were measured at various intervals of child growth between 5 and 156 months, and the sample consisted of children with exposure to MDS since birth, and those without this. When the children reached ten years of age, their brains were scanned at the Montreal Neurological Institute.
Contrary to popular belief, no correlation was found between MDS level and income. However, there was a positive correlation between a child’s amygdala size and level of cortisol – an important stress hormone – as well as the mother’s MDS score. Although the hippocampus, a structure responsible for retrieval of memory, has complementary functions to the amygdala, no difference in the hippocampal volume was detected. It is speculated that the change in the hippocampus may only be visible in later adolescence or adulthood. An alteration in the amygdala size may imply that this part of the brain is especially delicate and responsive to the quality of maternal care.
Any implications of the amygdala enlargement are yet to be discovered. However, this morphological change could be beneficial. “[When the baby is neglected,] the mother is not acting as a buffer between the baby and the environment,” explained Séguin. “The brain could compensate for it by growing the [amygdala] structure a little broader or larger.” This ensures protection and, ultimately, survival of the child.
In addition to the mother’s MDS level, there are other presumptions that may explain this physiological alteration. The amygdala enlargement may arise from the genetic transmission of the depressed mother. Further studies that investigate the hippocampal and amygdala volumes in siblings and twins may confirm the influence of genetics.
There are, however, precautionary steps that can be taken to minimize the undesirable effects on a child’s brain growth. For one, children often benefit from biparental care A level of paternal involvement may also influence the child’s brain development, and low paternal participation during infancy is shown to cause mental health problems. Moreover, Séguin speculates that a variety of experiences, such as enriched daycare environment and interactions with other children, may help reorganize the brain’s morphological development.