Research press release


Nature Neuroscience

Pregnancy changes mother’s brain structure



今回、Elseline Hoekzemaの研究チームは、妊娠、出産を初めて経験した25人の女性を妊娠前後の両方の時点で調べて、妊娠によって起こる脳の灰白質の構造変化を解明する前向き研究を計画し、実施した。この25人の女性は、初めて父親になった男性19人、子どものいない男性17人、出産経験のない女性20人と比べて、心の理論(自分自身または他人に思考、感情、意図などの心的状態があることを理解する能力)に関連する脳領域の灰白質が少なくなっていた。この構造変化のパターンを用いることで、出産経験のある女性の脳と出産経験のない女性の脳を区別することができ、出産後の乳児への愛着の質を予測することも可能になった。また、出産後の女性に自分の子(乳児)の写真を見せる実験では、他の乳児の写真を見せる場合と比べて、妊娠によって変化した脳領域の一部で神経活動が高くなっていた。その後行われた神経画像検査では、妊娠、出産を初めて経験した女性における灰白質の減少が、ほぼ全ての脳領域で出産後約2年間維持され、記憶に関連する脳領域である海馬だけで灰白質の容積が一部回復していたことが明らかになった。


Pregnancy leads to structural changes in the brain that persist for at least two years, according to a study of 25 first-time mothers published online this week in Nature Neuroscience. These changes occur in regions that are involved in social cognition and that respond to images of the mother’s infant. Furthermore, the extent of the changes can predict a mother’s attachment to her child.

Pregnancy is accompanied by drastic physiological and physical changes in the body due to extreme surges of hormones. Although we know that less radical hormonal changes - such as those seen during puberty - can modulate human brain structure and function, the structural changes within a mother’s brain as a result of pregnancy have yet to be determined.

Elseline Hoekzema and colleagues designed a prospective study that examined 25 first-time mothers both before and after pregnancy to characterize pregnancy-induced structural changes in their brains’ gray matter. Compared to the brains of 19 first-time fathers, 17 men without children and 20 women who had never given birth, first-time mothers exhibited reduced gray matter in regions associated with theory of mind, or the ability to attribute mental states such as thoughts, feelings and intents to themselves or other people. This pattern of structural changes could be used to distinguish the brains of women who had eventually given birth from those who did not, as well as predict the quality of mothers’ attachment to their infants in the postpartum period. The authors observed increased neural activity in some of these pregnancy-modified brain regions when they showed mothers pictures of their own infants, relative to images of other babies. Finally, a follow-up imaging session determined that almost all of these gray-matter reductions were maintained in the first-time mothers nearly two years after giving birth, except for a partial recovery of gray-matter volume in the hippocampus, a region associated with memory.

This study provides the first glimpses into the extensive changes in brain structure and function that result from first-time pregnancy. The authors suggest that these changes may prepare a woman for the social demands of imminent motherhood.

doi: 10.1038/nn.4458

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