Depression dulls down the normal brain activity that would prompt a mother to pick up her crying infant, according to a brain scan study by the University of Oregon. The research offers the first glimpse into the brain activity of depressed women and how they respond to recordings of crying infants, either their own or someone else’s.
A mother’s response to her crying baby affects the child’s development, said Dr. Jennifer C. Ablow, professor of psychology. For years, she has observed the connection between behavior and physiological responses, including the heart rate and respiration of new mothers (depressed and not), and when they respond to their crying infants.
The study used functional magnetic resonance imaging (fMRI), which is able to measure blood flow changes through magnetic field and radio frequency pulses, creating detailed images that display brain activity.
All 22 women in the study were first-time mothers whose babies were 18 months old. Scientists studied both group differences between women with chronic histories of depression and those with no clinical diagnoses, and the slight differences in brain activity related to current levels of depressive symptoms.
“It looks as though depressed mothers are not responding in a more negative way than non-depressed mothers, which has been one hypothesis,” said Dr. Heidemarie K. Laurent, professor at the University of Wyoming, who led the study as a postdoctoral researcher in Ablow’s lab. “What we saw was really more of a lack of responding in a positive way.”
Overall, brain responses in non-depressed mothers who listened to the sound of their own babies’ cries were evident on both sides of the brain’s lateral paralimbic areas and core limbic sub-cortical regions including the striatum, thalamus and midbrain; however, depressed mothers showed no unique response to their own babies.
Non-depressed moms had much stronger activity than depressed mothers in a subcortical cluster involving the striatum (specifically the caudate and nucleus accumbens), and the medial thalamus. These regions are strongly linked to reward and motivation.
“In this context it was interesting to see that the non-depressed mothers were able to respond to this cry sound as a positive cue,” said Laurent. “Their response was consistent with wanting to approach their infants. Depressed mothers were really lacking in that response. ”
Also, mothers who self-reported that they were more depressed at the time of their fMRI sessions had lowered prefrontal brain activity, especially in the anterior cingulate cortex, while hearing their own baby’s cries. According to Laurent, this brain area is associated with evaluating information and with planning a response to emotional cues.
The significance of the study, Ablow and Laurent said, is that depression can begin a long-lasting effect on the mother-baby relationship by blunting her response to the infant’s emotional cues.
“A mother who is able to process and act upon relevant information will have more sensitive interactions with her infant, which, in turn, will allow the infant to develop its own regulation capacities,” said Ablow.
“Some mothers are unable to respond optimally to their infant’s emotional cues. A mother’s emotional response requires a coordination of multiple cortical and sub-cortical systems of the brain. How that plays out has not been well known.”
Laurent believes the findings may suggest new implications for treating depression symptoms in mothers. “Some of these prefrontal problems may be changed more easily by addressing current symptoms, but there may be deeper, longer-lasting deficits at the motivational levels of the brain that will take more time to overcome,” she said.
We regard the study as a “jumping-off point” toward a better understanding of the neurobiology of a mother’s brain, said Ablow, also a co-director of the UO’s Developmental Sociobiology Lab.
“In our next study, we plan to follow women from the prenatal period through their first year of motherhood to get a fuller picture of how these brain responses shape mother-infant relationships during a critical period of their babies’ development,” said Ablow.
The study is published in the journal Social Cognitive and Affective Neuroscience.
Source: University of Oregon