Pregnancy is a transforming period in a person's life during which the body undergoes rapid physiological adjustments to prepare for parenthood, as we all know. What the broad hormonal alterations caused by pregnancy do to the brain is still a mystery.
Researchers
in Professor Emily Jacobs' group at UC Santa Barbara have created the
first-ever map of a human brain during pregnancy, shedding insight on this
understudied area.
"We
wanted to look at the trajectory of brain changes specifically within the
gestational window," said Laura Pritschet, lead author of a paper just
published in Nature Neuroscience (link) . Previous studies had taken snapshots
of the brain before and after pregnancy, she said, but never have we witnessed
the pregnant brain in the midst of this metamorphosis.
The
researchers studied one first-time mother's brain every few weeks, beginning
before pregnancy and continuing for two years after childbirth. The results,
gathered in partnership with Elizabeth Chrastil's team at UC Irvine, show
changes in the brain's grey and white matter throughout gestation, implying
that the brain is capable of remarkable adaptability well into adulthood.
Their
precision imaging approach allowed them to capture dynamic brain reorganization
in the participant in exquisite detail. This approach complements early studies
that compared women's brains pre- and post-pregnancy. The authors noted,
"our goal was to fill the gap and understand the neurobiological changes
that happen during pregnancy itself."
The
most pronounced changes the scientists found as they imaged the subject's brain
over time was a decrease in cortical gray matter volume, the wrinkly outer part
of the brain. Gray matter volume decreased as hormone production ramped up
during pregnancy. However, a decrease in gray matter volume is not necessarily
a bad thing, the scientists emphasized. This change could indicate a
"fine-tuning" of brain circuits, not unlike what happens to all young
adults as they transition through puberty and their brains become more
specialized. Pregnancy likely reflects another period of cortical refinement.
"Laura
Pritschet and the study team were a tour de force, conducting a rigorous suite
of analyses that generated new insights into the human brain and its incredible
capacity for plasticity in adulthood," Jacobs said.
Less
obvious but just as significant, the researchers found prominent increases in
white matter, located deeper in the brain and generally responsible for
facilitating communication between brain regions. While the decrease in gray
matter persisted long after giving birth, the increase in white matter was
transient, peaking in the second trimester and returning to pre-pregnancy
levels around the time of birth. This type of effect had never been captured
previously with before-and-after scans, according to the researchers, allowing
for better estimation of just how dynamic the brain can be in a relatively
short period of time.
"The
maternal brain undergoes a choreographed change across gestation, and we are
finally able to see it unfold," Jacobs said. These changes suggest that
the adult brain is capable of undergoing an extended period of neuroplasticity,
brain changes that may support behavioral adaptations tied to parenting.
"Eighty-five
percent of women experience pregnancy one or more times over their lifetime,
and around 140 million women are pregnant every year," said Pritschet, who
hopes to "dispel the dogma" around the fragility of women during
pregnancy. She argued that the neuroscience of pregnancy should not be viewed
as a niche research topic, as the findings generated through this line of work
will "deepen our overall understanding of the human brain, including its
aging process."
The
open-access dataset, available online, serves as a jumping-off point for future
studies to understand whether the magnitude or pace of these brain changes hold
clues about a woman's risk for postpartum depression, a neurological condition
that affects roughly one in five women. "There are now FDA-approved
treatments for postpartum depression," Pritschet said, "but early
detection remains elusive. The more we learn about the maternal brain, the
better chance we'll have to provide relief."
And
that is just what the authors have set out to do. With support from the Ann S.
Bowers Women's Brain Health Initiative, directed by Jacobs, their team is building
on these early discoveries through the Maternal Brain Project. More women and
their partners are being enrolled at UC Santa Barbara, UC Irvine, and through
an international collaboration with researchers in Spain.
"Experts
in neuroscience, reproductive immunology, proteomics, and AI are joining forces
to learn more than ever about the maternal brain," Jacobs said.
"Together, we have an opportunity to tackle some of the most pressing and
least understood problems in women's health."
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