Pregnancy and motherhood can permanently alter a woman’s brain and affect how it responds to treatments later in life, scientists say.
The latest findings on hormone therapy and brain function could have implications for the treatment of age-related neurodegenerative disorders in women, researchers said.
“Our most recent research shows that previous motherhood alters cognition and neuroplasticity in response to hormone therapy, demonstrating that motherhood permanently alters the brain,” said Dr. Liisa Galea from the University of British Columbia.
ADVERTISEMENT
A systematic review of the published scientific literature indicates that estradiol-based Hormone therapy (HT) may have more beneficial effects, while estrone-based HTs may have more detrimental effect on cognition and dementia risk in women.
Galea studied how two forms of estrogens, estradiol and estrone, affect neuroplasticity, which is how neural pathways in the brain change in response to various factors.
Her studies focussed on a specific brain region, called the hippocampus, which has important roles in memory and spatial ability, such as navigational skills.
ADVERTISEMENT
Both forms of estrogens increased the production of new cells in a part of the hippocampus called the dentate gyrus in young females.
However, only chronic estradiol, but not chronic estrone, significantly increased the survival of these new neurons, and increased the expression of zif268, a protein involved in neuroplasticity.
Chronic estradiol, but not chronic estrone, also improved performance of young female rats in a behavioural test called the water maze.
The water maze is a test of memory and orientation in which rats must find a submerged platform in water that they cannot see; they must instead rely on cues located around them to orient themselves and swim to the platform.
Rats receiving estradiol-based HT found the platform significantly better that rats receiving estrone-based HT.
Galea’s previous research had shown that motherhood causes changes in the architecture of connections in the hippocampus, so her team investigated whether the different forms of estrogens could have different effects on rats that had experienced motherhood once (primiparous rats) and on those who had not (nulliparous rats).
They found that estrone-based HT improved learning in middle—aged nulliparous rats, but impaired learning in primiparous rats of the same age.
These primiparous rats also showed a reduction in neurogenesis and zif268, a protein involved in neuroplasticity in the hippocampus.
“Hormones have a profound impact on our mind. Pregnancy and motherhood are life-changing events resulting in marked alterations in the psychology and physiology of a woman. Our results argue that these factors should be taken into account when treating brain disorders in women,” Galea added.