成为父亲会改变男人的大脑
Becoming a dad changes men's brains

原始链接: https://www.scientificamerican.com/article/how-becoming-a-dad-changes-mens-brains/

研究表明,为人父会引发显著的神经系统变化,这一发现挑战了“大脑的育儿适应性仅限于分娩母亲”的传统观念。研究显示,新手父亲的大脑会经历“大脑修剪”——即灰质减少,这很可能提高了照顾婴儿的效率;同时,与共情和奖赏相关的神经网络也会被激活。这些神经层面的转变是由实际的照护经历所驱动的,而不仅仅是受怀孕等生物学过程的影响。 尽管发生了这些变化,父亲在心理健康方面面临的挑战却常被忽视。大约十分之一的男性会经历父亲产后抑郁或焦虑,其症状通常表现为易怒、愤怒或药物滥用,而非典型的抑郁表现。与母亲在产后会定期接受心理筛查不同,父亲缺乏经过验证的筛查工具,且支持网络往往较小。此外,父亲心理健康问题的峰值通常出现在产后三到六个月,这正好与照护需求增加的时间点相吻合。专家认为,现有的支持系统必须从“以母亲为中心”的模式,演变为涵盖所有照顾者的包容性体系,以正视并满足所有照顾者的心理健康需求及不断变化的职责。

近期《科学美国人》发表了一篇关于为人父如何从生理上改变男性大脑的文章,在 Hacker News 上引发了热烈讨论。评论者们分享了个人经历,这些经历很大程度上呼应了文章中关于情感转变的观点,尽管每个人的具体感受大相径庭。 许多父亲表示,他们的共情能力显著增强——有人承认现在看电影时会掉眼泪——对情感信号的敏感度也随之提高。然而,这种共情能力的增强往往伴随着耐心的急剧下降。用户将这种对“废话”和低效率的零容忍主要归因于初为人父后极度的时间压力和疲惫感。 一些参与者质疑,这些报告的心理变化究竟是纯粹的神经学现象,还是仅仅由睡眠不足和育儿带来的繁重后勤需求所导致的副产品。另一些人则指出,父亲的产后抑郁和焦虑是真实存在但常被忽视的现象,在男性身上往往表现为愤怒或易怒。总的来说,评论者的共识是:为人父虽然会触发性格和生活重心深刻的改变,但这同时也是一个由生理和环境双重压力所塑造的、复杂且往往令人身心俱疲的转变过程。
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原文

Father’s Day is an opportunity to recognize the efforts of dads everywhere. But becoming a father is more than just a lifestyle change—it alters one’s brain, too.

Scientific American spoke with Devika Bhushan, a public health physician and adjunct faculty member at Stanford University School of Medicine, who studies gender norms, about the ways in which fatherhood affects men’s brains and the mental health struggles dads face. Bhushan also served as acting surgeon general of California in 2022.

The following article is based on our conversation with Bhushan.


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“Dad brain” is real

Most of the research on parental brain changes focus on those that occur during pregnancy and early motherhood. Much less attention has been given to the neurological and mental changes that occur in fatherhood, Bhushan says.

A 2014 study compared the brains of heterosexual, primary caregiver mothers, heterosexual, secondary caregiver fathers and gay primary caregiver fathers. All three groups showed brain changes in a “parental caregiving network” comprising a part of the brain’s cortex called the mentalizing network, which plays a role in visual processing and empathy, and a subcortical emotional processing network, which involves vigilance and reward processing. The mothers showed greater activation of the emotional network, whereas the heterosexual, secondary caregiver fathers had more activation of the mentalizing network. Gay, primary caregiver fathers displayed some changes in the emotional network that resembled those seen in heterosexual mothers, but they also showed some similarities to the brain changes seen in heterosexual fathers.

A more recent study in 2023 of men in Spain and California showed that they experienced reductions in gray matter after they became fathers—much like studies have shown in first-time mothers. This shrinking likely doesn’t represent a decline in brain function but rather a “pruning” of connections that could make the brain more efficient for the demands of caregiving.

Taken together, these studies suggest that at least some of the brain changes seen in new parents result from caregiving itself, not from the biological changes associated with pregnancy, birth and breastfeeding, Bhushan notes.

Given that people of all genders experience brain changes when they become parents, perhaps it’s not surprising that, just as mothers are vulnerable to postpartum depression and anxiety, fathers, too, can have similar mental health struggles.

Fathers can get postnatal depression, too

As many as one in 10 men will experience paternal postnatal depression or anxiety. The symptoms often look different in dads—anger or sudden outbursts, irritability and substance misuse, for example. Such postnatal depression can affect not only the father’s well-being but also the mother’s, as well as their child’s development, Bhushan says.

The American Academy of Pediatrics recommends screening mothers for postpartum depression at every doctor’s visit for their infants through the first six months. Mothers are typically screened using the Edinburgh Postnatal Depression Scale, but this is not validated for use in nonbirthing parents. Men also tend to have fewer social networks than women do, so they could have less support from friends or family to help them deal with mental health struggles.

Postnatal depression and anxiety tend to peak later in fathers than in mothers—closer to three to six months after the birth of a child. This may be because most fathers in the U.S. go back to work within two weeks of having a child, whereas mothers tend to stay home longer. As a result, mothers typically bear the brunt of the caregiving burden in the earliest weeks and months, whereas fathers may take on more responsibility later, around the time many mothers go back to work.

In the U.S., fathers have taken on an increasingly larger share of childcare responsibilities in recent years—and with it, an increased share of the stresses and burdens. Bhushan says maternal support systems should be restructured to parental systems that cater to both mothers and fathers.

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