Subclinical maternal depressive symptoms modulate right inferior frontal response to inferring affective mental...

Being a mother of young children increases the risk of depression characterised by deficits in inferring what a person is feeling, i.e., affective theory of mind (aToM). Despite the adverse consequences for mothers, children, families, and society as a whole, little is known of how the brain functions underlying aToM ability are affected by subclinical maternal depressive symptoms, and act as a risk indicator for major depressive disorders (MDD).

Thirty healthy mothers with varying levels of depressive symptoms underwent functional magnetic resonance imaging (fMRI) while performing mind-reading tasks based on the emotional expressions of adult eyes and infant faces.

In the adult eyes-based mind-reading task, mothers with more severe depressive symptoms showed less activation in the right inferior frontal gyrus (IFG), a central part of the putative mirror neuron system (pMNS). This was unrelated to behavioural performance decline in the task. However, brain activation involved in the infant face-based mind-reading task was not affected by depressive symptoms.

Although aToM ability, assessed by mind-reading tasks, can be distinguished from empathy, these can be interacting functions of the pMNS, wherein they could mutually affect each other.

These findings suggest that functional activation of the right IFG, which underlies aToM ability, has variable vulnerability to maternal depressive symptoms according to the type of social signal. This functional decline of the right IFG may be a risk indicator for clinical maternal depression, which is associated with impaired social functioning and communication conflicts with family members and other social supporters.