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How Children Absorb Their Parents’ Stress
Researchers have been examining other ways in which parental stress can be
passed on from parent to child. Some of their findings are surprising. Scientists
at the University of Haifa have found, for instance, that children may even
inherit the effects of a mother’s stress from events that occurred before
conception through their DNA.
Mildly stressed female lab rats who were mated with nonstressed male rats
had offspring that showed more anxiety than babies born to nonstressed mothers.
Stressed female rats showed an increased expression of a particular protein that
prompted cells to release
more
hormones related to stress and anxiety. The more
this protein was expressed, the more stressed the female rat became, and the
more stressed her babies were. Even more startling, this anxious behavior was
passed along from a mom to her offspring epigenetically—the stress had nothing
to do with the later quality of parental care: this stress protein
already existed
in
large concentrations in the eggs of these previously stressed females—before the
mom rats became pregnant.
This suggests that a female’s eggs were transferring “soft-wired information.”
In other words, Mom’s eggs were transmitting Mom’s trauma to her babies
before they were born.
All this research has been done on rats, and not humans, since we can’t take
out parts of the human brain, slice them up, and study them. But it gives support
to the idea that stress may be transferred from a mother’s cells to her child in
ways we are only beginning to understand.
Stress can also be transmitted between parent and child through what
researchers call “empathic stress.” Studies show that merely observing another
person in a stressful situation can trigger a physical stress response in you. If
you’re with someone who’s stressed out, their stress can become your stress, not
just emotionally, but biologically: your cortisol levels rise along with theirs. This
is “empathetic stress.”
Stress can affect infants, in the same way, through what’s known as
“contagious emotions.” Researchers at the University of California, San
Francisco (UCSF), set out to determine how this happens between mother and
child. “Our earliest lessons about how to manage stress and strong negative
emotions in our day-to-day lives occur in the parent-child relationship,” says
Sara Waters, a lead researcher in the study. And it appears that this transmission
goes far beyond words or even visible expressions.
Waters and her colleagues recruited sixty-nine mothers and their twelve-to
fourteen-month-old infants. They hooked up mothers and children to
cardiovascular sensors and took baseline readings when moms and infants were
sitting and resting together. Then, they separated mothers from their babies and
asked them to deliver a prepared five-minute speech to evaluators—then answer
evaluators’ questions for another five minutes.
A third of the mothers were treated quite positively by evaluators, who
listened, nodding their heads, smiling as these moms spoke, leaning forward as if
to ferret out more. Another third of the moms received negative feedback;
evaluators frowned, shook their heads, and crossed their arms as if they didn’t
like what they were hearing. And another third of the moms didn’t interact with
evaluators at all.
Afterward, the moms who received negative feedback showed increased
cardiac stress and admitted they had more negative feelings than positive ones.
Researchers then reunited babies with their moms.
Those infants who were placed back in the arms of moms whose talks had
been reviewed negatively by evaluators picked up on their mothers’ emotional
distress right away. The greater a mom’s physiological stress, the greater her
infant’s physiological stress response was once the child was back in the
mother’s arms. These infants’ heart rates went up—spiking higher than they had
been at baseline—within moments of being reunited with their stressed-out
moms.
These babies couldn’t talk and express what they were sensing. They just
knew something was off. Mommy was stressed. And so were they.
These infants, says Waters, “caught the psychological residue of their
mother’s stressful experiences.” She explains: “We may overlook how
exquisitely attuned babies are to the emotional tenor of their caregivers before
they are verbal and able to fully express themselves.” An infant “may not be able
to tell you that you seem stressed, or ask you what’s wrong, but as soon as she is
in your arms, she is picking up on the bodily responses that accompany your
emotional state—transmitted through vocal tension, heart rate, facial
expressions, odor, or other difficult-to-see mother-to-child avenues of ‘stress
contagion.’ ” In this way, an infant may silently absorb her parents’ negative
emotions into her own tiny body.
Parental conflict—which often increases when new parents are coping with
the stress of sleepless nights, new schedules, less time to devote to their
relationship, and perhaps differing views over what’s best for baby—can also
affect how reactive an infant’s brain is to stress.
Research shows that babies can also pick up on and absorb the stress of
parental bickering—including when the baby is sleeping. Oregon Health and
Science University researcher Alice Graham, PhD, discovered this when she
asked mothers to fill out surveys on how often they tended to argue with their
partners at home, and then examined the brain activity of their six-to twelve-
month-olds with functional magnetic resonance imaging, or fMRI.
Graham’s team put headphones on these babies while they were sleeping
during the fMRI scan, and played nonsense phrases read in both neutral and
angry voices. Babies whose parents argued a lot at home showed a stronger
neurological reaction when they heard angry tones in areas of the brain that are
associated with processing stress and emotion.
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