Boys whose mothers suffer from depression while pregnant are more likely to be hyperactive and aggressive, a study has revealed.
Researchers from Canada also found that children are more likely to develop depression by age 18 if their mothers suffered from prenatal depression.
It is estimated that up to a fifth of women suffer from symptoms of depression during pregnancy — with the full effects on the foetus unclear, the team said.
Prenatal depression is linked to behavioural and developmental problems in children, but exactly how it leads to these changes has been unclear.
According to the researchers, however, one explanation could lie in weakened brain connections that affects the child’s behaviour.
Weakened white matter in the brain was also linked to increased aggression and hyperactivity in male children, the study found.
In their study, the research team from the University of Calgary, Canada, examined 54 expectant mothers and the children they went on to give birth to.
At several points during their pregnancy, the women were asked to complete a survey asking them about whether they were experiencing symptoms of depression.
After the children were born, the researchers used so-called ‘diffusion MRI’ — an imaging technique that can reveal the strength of structural connections between different regions of the brain — to examine the children’s white matter.
Greater symptoms of prenatal depression in the mothers was found to be associated with weaker white matter connections between the brain regions involved in emotional processing among the children, the researchers reported.
These relative connective weaknesses could lead to so-called ‘dysregulated emotional states’ in the children — in which they would be unable to manage the intensity and duration of negative emotions such as fear, sadness or anger.
This could explain why the children of depressed mothers have a higher risk of developing the illness themselves, the researchers noted.
The findings highlight the need for better prenatal care to recognise and treat prenatal depression in order to support mothers and the development of their children, the researchers said.
‘Understanding how prenatal maternal depression impacts child behaviour is critical for appropriately treating prenatal maternal mental health problems and improving child outcomes,’ the researchers said.
The study revealed ‘white matter changes in young children exposed to maternal prenatal depressive symptoms.’
‘Children of mothers with worse depressive symptoms had weaker white matter connectivity between areas related to emotional processing.’
‘Furthermore, connectivity between the amygdala [the area of the brain that deals with emotions] and prefrontal cortex mediated the relationship between maternal depressive symptoms and externalising behaviour in boys
This, they explained, showed that ‘altered brain structure is a possible mechanism via which maternal prenatal depression impacts children’s behaviour.’
‘This provides important information for understanding why children of depressed mothers may be more vulnerable to depression themselves and may help shape future guidelines on maternal prenatal care.’
The full findings of the study were published in the Journal of Neuroscience.