‘Baby brain’ is real. Increasing evidence suggests having kids causes big changes in our grey matter, and not always for the worse. Ben Spencer, science editor and frazzled father of two, explains.
This was a full-on meltdown, an end-of-days tantrum. Fists clenched, his face streaming with tears and snot, my three-year-old son was furious. “Daddy!” he wailed, throwing his head back. “You’ve ruined it!”
I had cut the potato waffles precisely into quarters and sprinkled grated cheese over the top, just as he had wanted them the previous week. “The cheese should be on the side, not the top,” he screamed, red-faced. “And I didn’t want them cut up!”
I could feel my stress levels rising. But on a rainy weeknight, with more work to tackle once the kids were in bed, an escalating battle was something I did not need. My brain was whirring, considering my options. My instinct was to shout back. I could tell him to eat up or go to bed hungry. Or I could slide the waffles over to my older son, aged seven, who had cleared his plate, and make another batch for the little one.
If you have young kids you might be wincing sympathetically, recalling similar conflicts in your own household. Parents of older children may think I need to get a grip and lay down some discipline. And those without children are probably just baffled, wondering how some toasted waffles could prompt such drama.
But I have a parent’s brain. Scientists have known for some time that “mum brain” - where new mothers experience scattiness, even memory loss - is real. It turns out that “dad brain” is a thing too. But a parent’s brain doesn’t develop in the way you might think. It’s easy to assume that child rearing causes some sort of neurological damage, our brains addled by sleep deprivation and stress. In fact parents’ brains are finely tuned machines - highly evolved in response to thousands of generations of tiny screaming humans.
Scientists now know that motherhood in particular triggers the biggest neurological change of any point since childhood, even more dramatic than that seen in teenagers. They used to think that these alterations were temporary - a fleeting hormonal surge required for pregnancy, labour and the early months of infancy. But emerging evidence suggests at least some of this transformation is lasting, persisting for at least six years, with some changes still seen decades later. They call this period of change matrescence. And recent research reveals that new fathers also experience a neurological metamorphosis, especially if they take a hands-on approach to parenting.
On a good day the parental brain is our superpower, it gives us the ability to foresee our child’s every want and need, helping us to nurture and shape a fully functioning citizen of the human race. On a bad day - and, let’s be honest, there are a few of those - it simply helps us survive.
“The human child is so dependent for so long,” says Gina Rippon, professor emeritus of cognitive neuroimaging at Aston University. “Baby giraffes get up on their feet within two minutes of birth and off they go. Human parenting is probably the most difficult form of parenting there is.”
In the modern world, where men and women often juggle child rearing with demanding careers, it can seem harder than ever. To cope, our brains need some tweaking, some specialisation. After speaking to leading neuroscientists, psychologists and anthropologists, I’ve built up an idea of what happens to the brains of mothers and fathers.
This is my brain on parenthood. It is probably yours too.
Mum brain
Women undergo huge changes during pregnancy. Growing baby bumps, swelling feet and morning sickness are obvious. The body is also flooded with new hormones: oestrogen and progesterone support the foetus in the early weeks before the placenta takes over, oxytocin triggers contractions and promotes bonding, and prolactin starts lactation. The endocrine system - the network of glands, tissues and organs that produces hormones to regulate our bodily functions - goes into overdrive. As the writer Lucy Jones puts it in Matrescence, her book on motherhood: “It is likely the most drastic endocrine event in human life.” These changes also resculpt the brain.
Last September scientists at the University of California, Santa Barbara published a study in which they scanned the brain of a 38-year-old woman every few weeks from before conception until two years after childbirth. The 26 scans revealed pronounced changes over the period, with “few regions untouched by the transition to motherhood”, the authors said in the journal Nature Neuroscience.
The most obvious change was a decrease in the volume of grey matter, the wrinkly outer layer of the brain involved in memory and emotions. This loss of brain tissue may seem like a bad thing, reinforcing the idea of a scatty “mum brain”. There may indeed be a short-term impact on memory. But scientists think this is in fact “synaptic pruning”, a shedding of unnecessary tissue to enable new connections to be forged.
The location of car keys or the password for an email account fades into insignificance at such a time. Unimportant memories are culled as the brain becomes more efficient and streamlined, preparing a new mum to learn the skills of child rearing and focus her attention on keeping her offspring alive.
The impact on memory, however, is temporary and minor - and there is some evidence that, long-term, the power of recall might actually be improved.
At the same time the amygdala - a small almond-shaped structure, one of a number of interconnected parts that make up the limbic system of the brain, responsible for processing sensory information - has a surge in activity. This is why new parents are primed to jolt awake at the sound of crying and become hyperalert to signs of danger in a playground or on the street. But the way these signals are processed also changes, with the stress response triggered by crying becoming damped down over time in order to stop parents losing their minds from the constant noise.
Rippon says: “In the middle of this we also have the tiny little infant, who is a social manipulator of the highest order. They’re born with their social radar finely tuned - and that’s how they survive.”
Mothers becomes highly attuned to these signals as their reward system is rewired inside the hypothalamus - a small part of the brain that controls many bodily functions, including sleep, hunger and body temperature. A region of the hypothalamus called the medial preoptic area is filled with new receptors for oxytocin, the “love hormone”. The hypothalamus also starts pumping out dopamine, the “feelgood” hormone. The smell of a baby’s head, every smile or laugh, triggers this reward circuit. Studies on mother rats suggest raising their pups can be more rewarding in terms of dopamine production than cocaine.
Dad brain
Scientists used to think that these changes were unique to mothers. But in recent years researchers have found similar changes of 10 take place in fathers.
The night my first son was born I sat over his plastic NHS crib all night, too frightened to sleep in case he stopped breathing. He had been born via emergency caesarean after a four-day labour and my wife was confined to her bed, recovering from surgery. Our boy had suspected sepsis, so was in intensive care on a different floor. It was me who put on his first nappy (badly) and spent the night annoying the nurses, knocking out his tubes and wires each time I picked him up.
As I did so, my brain was changing. Studies tell us new dads see their oxytocin levels rise as testosterone, which is involved in aggression and competition, falls. Even prolactin - the hormone that promotes lactation in breastfeeding mothers - can rise in men.
This is not universal. The changes seen in mothers do not always kick in for dads. “Fathers have the capacity to be involved caregivers but it’s not obligate - it doesn’t always happen,” says James K Rilling, professor of psychology at Emory University in Atlanta, Georgia, and the author of Father Nature.
Some will say that women are therefore better hardwired to be caregivers than men. But dads who do care for their children experience remarkably similar changes to the reward and caring centres of their brains. “The neuroscience shows fathers are just as capable as mothers,” Rippon says.
Women who bear children and give birth have a head start - the vast hormonal, physiological and neurological changes they undergo in pregnancy are a necessity, not a choice. Whether dads develop similar circuits seems to be influenced by how much time they spend with their children in the early years - a core argument for paid shared parental leave.
“Traditional models of parenting - where mothers are hands-on carers and fathers are breadwinners - reinforce gendered brain responses,” Rippon says.
So if a dad doesn’t see changing nappies as his job, it is less likely he will wake up in the night when the baby cries. His brain won’t develop the coping mechanisms. He will also be more likely to lose his rag when his kids start throwing tantrums.
Darby Saxbe, professor of psychology at the University of Southern California, is one of the growing number of researchers with hard evidence that “dad brain” is real.
She scanned the brains of first-time fathers in Barcelona and Los Angeles during their partners’ pregnancy and again when the babies were born. “We found that men showed volume decreases in a lot of the same areas that had been seen in women,” Saxbe says. “We saw the same overall pattern of brain change. But the men’s changes were more subtle and they were more variable.”
Crucially, fathers’ intentions - whether they planned to take time off when the child was born, and whether they already felt bonded to their unborn child during pregnancy - influenced whether the brain changes came about. “The dads who are more motivated and spent more time with the babies had more brain change,” Saxbe says.
Genetics are irrelevant
All of this makes evolutionary sense. It takes more than one person to raise a child. And it’s not always the father who steps up. It might be a grandmother, an aunt, a stepfather or adoptive parents. It might be two dads or two mums.
The extent to which the wiring of the brain is activated is nothing to do with a genetic link to the child. It seems, rather, to be one of exposure. To have a full-blown parent brain, however, you need to be the one taking responsibility for the child.
The neuroscientist Ruth Feldman, a professor at Reichman University, near Tel Aviv in Israel, scanned the brains of 89 couples with new babies. Roughly half of the couples were heterosexual, with a “traditional” division of labour — the mother acting as primary caregiver and the father a secondary or “helper” parent. The rest of the couples were gay dads, with parenting shared between them. The participants had their brains scanned while watching videos of themselves playing with their own babies. All the parents showed activation in the cortex, the part of the brain that cognitively processes a child’s actions and calculates what they might need.
There were differences, however. The mothers’ amygdala, which processes sensory cues, showed nearly a fivefold surge in activity when watching their own children than when they weren’t. Their partners, the “secondary carer” men, saw a small bump in activity, but not nearly as much as the mums. But among the gay dads - each of them joint “primary” carers - the amygdala saw a surge as big as those seen in the mothers. Crucially, whether the gay dad was the genetic father made no difference.
Sarah Blaffer Hrdy, a renowned American anthropologist and primatologist, summarises the findings in her book Father Time. Changes to the amygdala were seen only “when the baby’s safety and wellbeing had become that man’s primary concern day after day”. When a man took on the role of primary parent, rather than an assistant, he “found himself steeped in the sights, smells, sounds and other cues from a baby whose wellbeing depended on him”. Only then did his brain show change to the same degree as that seen in a mother.
It is too simple to say that these circuits are simply switched on and off at will. But intention, necessity and hands-on time with a child all play a role in activating them. “It is maybe not a conscious decision,” says Saxbe at the University of Southern California. “There’s bonding and love involved. And it takes repetition, practice and investment. Great fathers are made, not born.”
Do our kids f*** us up?
It isn’t all domestic bliss. Parenting is exhausting and emotional. Most evenings, when the kids are finally in bed, my wife and I collapse on the sofa, too battered to think about feeding ourselves. The worst thing is the sleep deprivation, particularly when they are very small. When parents don’t get enough sleep it scrambles our ability to organise memories, perhaps another reason for the scatty element of “parent brain”.
Sleep deprivation also exaggerates dopamine signalling in the reward circuits, which is why some people cope by wolfing down junk food or drinking too much. Sleep problems can also disrupt the working of the amygdala, distorting how we read social cues, perhaps a trigger for the ending of so many relationships in early parenthood.
It is no surprise that eight in 10 women suffer so-called “baby blues” and one in 10 have postnatal depression. Far more severe is postpartum psychosis, a mental illness that can involve confusion, delusion and hallucinations, which affects one in a thousand new mothers. And it’s not just mothers - about one in 10 new fathers suffer from depression in the months after a baby is born.
When Saxbe carried out her brain scanning study on new dads, she found it was those who were more involved - the ones who had the greatest changes to their brain - who suffered the most.
“We know that early parenthood kind of sucks for mums because it can be depressing and isolating and repetitive,” she says. “So this might be evidence that, to whatever extent dads are investing more, they might be showing some of the same psychological health repercussions.”
There are two explanations. First, the more hands-on you are, the more you will feel the difficulties of parenthood. But, second, the reduction in testosterone among new dads might affect their mental health. “When men have lower testosterone after the birth, they are more likely to report symptoms of postpartum depression,” Saxbe says. “But their partners report fewer symptoms of postpartum depression. It’s actually better, if you’re a mum, to have a partner with lower testosterone.”
Fatherhood, as with motherhood, is a matter of give and take. And when parents raise children as a genuine joint enterprise, studies suggest their relationship may be strengthened. The empathy and caring circuits, renewed by parenthood, have a benefit for their partnership too.
There is another silver lining to all this, though it is one that may be viewed with scepticism by exhausted parents just about clinging on to their sanity. The brain doesn’t just bounce back from the demands of parenthood. There is some evidence that it might improve its functioning. All that multitasking has a lasting benefit.
One study, published in 2020, suggested that long-term changes to the parental brain improve its functioning. Analysis of 13,000 MRI scans in the UK Biobank - the world’s largest collection of biomedical data - found that mothers and fathers who had brought up two or three children had a significantly lower “brain age” (a marker for the health of their brain compared with their real age) than those who had no children. They also had faster response times and made fewer mistakes in a visual memory task. You may be tired, stressed and overwhelmed, but parenting might just keep you young.
Having learnt all that, I reassessed what happened in my brain during the wafflegate incident. As the crisis unfolded at the dinner table, my amygdala was busy making sense of the sights and sounds assaulting my senses, processing my son’s crying and toning down my stress response.
My prefrontal cortex, which regulates my emotions, was running at full blast, reining in my natural instincts to fight back. My reduced testosterone levels damped down the fight-or-flight response, stopping me from screaming back or storming out. And my boosted oxytocin levels increased my compassion and empathy, helping me see the whole event from the point of view of my child: a tiny growing boy desperately trying to exert some control in a world in which his every act is dictated by others.
I gave in, pushing the plate over to my older son, and got up to make another plate of waffles.
Written by: Ben Spencer
© The Times of London
