First-Time Dads May Experience Brain Shrinkage, Scientists Find

Becoming a new parent is an adjustment for both men and women.

A dozen or so previous studies have shown that motherhood can change the structure of a person’s brain, and yet fatherhood is comparatively overlooked.

Now, new international research has identified neurological changes amongst first-time fathers as well.

The study is only small, but it suggests that the neural substrates of parenthood are not exclusive to mothers. Men, as it turns out, can also be impacted by their new role as a parent, albeit in a less pronounced and uniform way.

On average, the researchers found new fathers lost a percentage or two of cortical volume following the birth of their first child.

This shrinkage was mainly confined to an area of the brain known as the ‘default mode network‘, which is associated with parental acceptance and warmth.

At first, a loss in cortical volume might sound like a bad thing, but it can actually indicate a refinement of the brain that makes connecting with a child more powerful and efficient.

Similar cortical losses in mothers, for example, are associated with greater neural responses to a child and stronger child-parent attachment.

Previous studies have shown that there are subtle neurological changes in the male brain following the birth of a child, but the little evidence that has been collected has proved mixed and conflicting.

Some studies show increases in gray matter following the birth of a child, while others show losses. Different regions of the brain have also been implicated, and few methods have differentiated between childless men, first-time fathers, and fathers of multiple children.

The new research is more rigorous than most. It is based on magnetic resonance imaging ( MRI) data from 40 heterosexual first-time fathers, half of whom were based in Spain and half of whom were based in the United States.

The expectant fathers in Spain participated in brain scans before their partners’ pregnancies, and then again a few months after birth.

The expectant fathers in the US, on the other hand, participated during the mid-to-late stages of their partners’ pregnancy, and then again seven to eight months postpartum.

The new research also included a control group of seventeen men without children based in Spain.

Gathering together all their data, the two laboratories compared the volume, thickness, and structural properties of the male brain in all three groups.

Compared to similar studies on new mothers, first-time fathers in the current study did not show changes in their limbic subcortical network. This makes sense as this part of the brain is associated with pregnancy hormones.

Still, just because fathers aren’t carrying their offspring as they grow and develop, it doesn’t mean their brains aren’t impacted by parenthood. Recent studies, for instance, have shown that men can be just as impacted by postpartum depression, although it’s rarely recognized as a problem.

Part of the issue may be that brain plasticity among new fathers is less pronounced than it is in new mothers. But thankfully, brain imaging technology can help experts see even subtle neurological changes.

In the current study, first-time fathers in both Spain and in California did not show changes in their subcortex, which is associated with reward and motivation.

They did, however, show signs of brain plasticity in their cortical gray matter, which is largely involved in social understanding – and the researchers also found pronounced reductions in the visual system’s volume.

More research on this visual brain region and its role in parenthood is needed, but the findings do align with a recent study in 2020 that found fathers are better at visual memory tasks than those men without children.

“These findings may suggest a unique role of the visual system in helping fathers to recognize their infants and respond accordingly, a hypothesis to be confirmed by future studies,” the authors of the new paper write.

“Understanding how the structural changes associated with fatherhood translate into parenting and child outcomes is a largely unexplored topic, providing exciting avenues for future research.”

The study was published in the Cerebral Cortex.

Source: sciencealert.com

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