The Brain Shrinks as We Age and During Major Transitions. But Surprisingly, It Seems to Take a Break From Rewiring During Menopause

The brain goes through substantial changes during puberty and pregnancy, both marked by major hormonal shifts. Yet during the third female hormonal transition period—menopause—the organ seems to hit pause on rewiring. That’s according to a new study that examined scans of 1,095 female brains across three life stages: first menstrual cycle, pregnancy and menopause.

The work, published in the journal Nature Communications on September 8, hints that the loss of gray matter volume typically tied to hormone changes doesn’t happen during menopause. What’s more, aging-related brain shrinkage also temporarily halts during this time. The findings address an important gap in our understanding of the female brain.

Although women make up half the world’s population, only 2 to 6 percent of neuroscience studies are conducted with exclusively female samples, and fewer than 5 percent of studies treat sex as a factor in analysis, the researchers write in the paper. Moreover, “no one had looked at the changes in the whole brain matter in this menopause transition before,” said study co-author Sophie van ’t Hof, a cognitive neuroscientist at Amsterdam University Medical Centre, during a press conference, reports Claire Cameron at Scientific American. Scientists already know from past research that during puberty and pregnancy, the volume of gray matter dramatically shrinks.

Gray matter largely consists of nerve cell bodies that help process information, and much of it is in the brain’s wrinkly outer layer, or cerebral cortex. Shrinkage during these transitional periods likely happens because the organ rewires its neural networks as it prepares for a new stage of life. Up to 80 percent of pregnant people report memory problems, which can continue into early postpartum.

It’s often called “mommy brain” or “baby brain.” Studies suggest these cognitive changes occur because the brain is reorganizing itself, possibly to prepare for bonding with the baby, among other benefits. At the same time, the brain also gradually loses gray matter as we age. Biobank and several studies conducted at Leiden University in the Netherlands.

They analyzed brains of different participants at two time points: before and after their first period, before and after their first or second pregnancy, or before and after menopause. They also included control groups, such as adolescents stably pre- or post-first menstrual cycle and adults pre- or post-menopause. The onset of puberty was linked with a monthly decline of 0.13 percent of gray matter, while pregnancy was associated with a monthly reduction of 0.12 percent, the team found, aligning with previous findings.