First-time fathers may experience brain shrinkage, study suggests

First-time dads lose a small fraction of the volume of some brain regions, a new study has revealed.

The study published last week in the journal Cerebral Cortex assessed structural neuroimaging data in expectant fathers before and after the birth of their first child and compared it with data from a control group of 17 childless men.

The results highlighted some neurological changes in new dads as they transition to parenthood.

Studies have previously shown that childbirth can bring about adaptations in the brains of both parents.

However, while earlier research has shed light on this process in mothers, scientists, including those from the University of Southern California in the US, say “very few studies” have examined such adaptations in men transitioning into fatherhood.

As part of an international collaboration between two labs in Madrid and California, the researchers found that anatomical changes in volume, thickness, as well as area of the brain’s outermost cortex region were linked to transition into fatherhood.

Researchers found significant changes in the brain’s default mode network (DMN) in new dads – which is associated with parental acceptance and warmth.

This is a network of interacting brain regions which has been found to be active when people are not focused on the outside world.

Scientists have reported in previous studies that the DMN is typically involved during times when people might be daydreaming, envisioning the future, recalling memories, or just thinking without particular goals or aims.

Researchers reported trends of cortical volume reductions within the “default mode network and visual networks,” and a “preservation of subcortical structures” across both samples of first-time fathers. They said the observed trends persisted after controlling for fathers’ and children’s age at the postnatal scan.

They wrote in the journal: “This study provides convergent evidence for cortical structural changes in fathers, supporting the possibility that the transition to fatherhood may represent a meaningful window of experience-induced structural neuroplasticity in males.”

While researchers acknowledge that the sample size of the study is small, they say the findings suggest the neurological effects of parenthood may not be exclusive to mothers.

Compared to similar studies on first-time moms, researchers say the new dads in the latest study did not show changes in a region of the brain called the limbic subcortical network that is also involved in behavioural and emotional responses.