MRI scans have revealed that children of depressed mothers have a larger amygdala, a part of the brain associated with emotional responses, researchers from the University of Montreal explained in the Proceedings of the National Academy of Sciences (PNAS). The authors suggest that the brains of children are sensitive to levels of child care quality. The scientists focused on the brains of ten-year-old children whose mothers had depression symptoms throughout their lives.

The authors wrote that prior studies had observed similar changes in the brains of adopted children who had been raised in orphanages – in such cases, the changes were greater. The authors believe that the key factor is personalized attention to a child’s needs.

Drs. Sophie Parent and Jean Séguin wrote:

“Other studies have shown that mothers feeling depressed were less sensitive to their children’s needs and were more withdrawn and disengaged.”

According to experts, the amygdala is involved in how we respond emotionally to events and information – it contributes to how we behave when faced with potential risks.

During our early years we know little about the world around us – our need to learn about the danger or safety of new experiences may be greater then.

Animal studies, specifically with primates, have shown that the amygdala’s development occurs most rapidly immediately after birth.

Lupien said:

“We do not know if the enlargement that we have observed is the result of long-term exposure to lower quality care. But we show that growing up with a depressed mother is associated with enlarged amygdala.

Having enlarged amygdala could be protective and increase the probability of survival.

The amygdala is related to the release of glucocorticoids, types of stress hormones. The scientists observed that levels of glucocorticoids among the offspring of depressed mothers in the study spiked considerably when they faced unfamiliar situations, i.e. they experienced elevated levels of stress.

Adults brought up by depressed mothers have demonstrated higher levels of glucocorticoids and a greater glucocorticoid reaction in laboratory stress tests.

The authors wrote:

“What would be the long term consequences of this increased reactivity to stress is unknown at this point.”

The authors say they do not know why the amygdala of these children is enlarged. They point to a previous study that found that children who were adopted earlier in life into well-off families did not have enlarged amygdala.

Lupien said:

“This strongly suggests that the brain may be highly responsive to the environment during early development and confirms the importance of early intervention to help children facing adversity. Initiatives such as prenatal and infancy nurse home visits and enriched day care environments could mitigate the effects of parental care on the developing brain.”

Séguin added:

“Future studies testing the effects of these preventive programs and observational studies involving children exposed to maternal depressive symptoms at different ages, and consequently for different lengths of time, should provide more insight into how this occurs, its long term consequences, and how it can be prevented.”

Written by Christian Nordqvist