How stress gets under the skin


Published on Psychology Today


We all know what it’s like to feel stressed out. After two years of what feels like a never-ending global pandemic, mental health issues like anxiety and depression are more common than ever—especially for parents who are juggling the added stress of navigating the closing and opening of schools, children who are still too young for a vaccine, and oftentimes their own full-time jobs. Although we are living in unprecedented times, chronic stress—or stress that is consistent and overwhelming for long periods of time—is not new for some of us. Individuals who experience trauma, like refugees who are trying to escape an oppressive government, or families who struggle with poverty, live with chronic stress for years or even decades at a time. As a result, researchers have long-been investigating the effects of parental stress on their children.


Classic research has shown that children who live in stressful environments can end up with all sorts of behavioral and emotional problems at some point during development. For example, parents’ own anxiety and household stress has been linked to their children’s emotional problems, including behavior issues, aggression, anxiety, and depression (Fields et al., 2021). Maternal stress has also been linked to factors in infancy that predict later anxiety as infants get older, namely a difficult temperament or a temperament characterized by a lot of negative emotions. Further, maternal anxiety and depression are associated with children’s impulsiveness and problems with attention (Van den Bergh, et al., 2017).


Importantly, stress can begin to impact a child before it's even born. For example, mothers who experience some sort of trauma during pregnancy, like mothers who were pregnant during the Holocaust or had to evacuate the World Trade Center on 9/11, tend to give birth to infants who are at greater risk for depression and anxiety. These infants also have significantly more birth complications including impaired uterine blood flow, preterm birth, and low birth weight. These birthing issues can lead to hypertension or diabetes later in life (Bowers & Yehuda, 2016). This suggests that the effects of both trauma and chronic stress can not only get under the skin, affecting both the mother and her fetus’ biology, but that it can also be transmitted from one generation to the next.


Newer research on this topic has involved scanning fetuses’ brains through their mothers’ pregnant bellies to examine the neurobiological consequences of chronic stress. In general, this research has shown that stress in the mother is associated with decreased functionality in the brains of their fetuses (Nelson et al., 2020). For example, in a recent study, researchers scanned over 100 pregnant mothers, and found that maternal stress was associated with decreased functional brain connectivity in the fetus. In other words, stressed out mothers had fetuses with decreased functional brain activity when compared to mothers who were less stressed. Importantly, infants of the stressed mothers were also born sooner, consistent with previous research linking prenatal stress to birth complications (Thomason et al., 2021).


I know this sounds bad, and for some infants it is, but changes in fetuses’ brains as a consequence of maternal stress is actually a sign that our developing brains adapt to the potential challenges an infant can face in their environments. Unfortunately, for some of us, that includes stressful circumstances. In circumstances like poverty, the changes we see in fetuses’ brains might function to enhance the fetus’ ability to cope or function in a harsh environment. For example, individuals in poverty have been shown to be more focused on current threats and opportunities instead of planning for the distant future. Although this has been viewed as impulsive or impatient behavior, this behavior makes a lot of sense if the future is uncertain, and there are big problems to face in the here and now (Frankenhuis & Nettle, 2020). Indeed, early life stress is predictive of a shorter life span, and as a result, life moves a little bit faster (Sosnowski et al., 2021). Accordingly, children who grow up in stressful circumstances might show faster maturation of certain parts of the brain, particularly the parts that deal with threat (e.g., Gee et al., 2013), and have even shown evidence of faster maturation of the body, including their permanent molars (McDermott et al., 2021)!


Although these changes in fetuses based on maternal stress are natural reactions to developing in a stressful environment, it doesn’t mean we shouldn’t try to help. Again, children who grow up in stressful environments can end up with all sorts of behavioral and emotional problems. The first thing we can do is try not to judge or blame moms for being stressed; this isn’t usually something they can help, especially mothers who are caring for children during traumatic circumstances or while they are struggling with poverty. Instead, we can provide them with both financial and social support to help reduce both their internal stress, and the stressful environment that surrounds their developing children.


Very recently, the Baby’s First Years Study started randomly assigning mothers who are living in poverty to receive a cash gift of either $333 per month or $20 per month. They found changes in brain reactivity of infants whose mothers received the larger cash gift in areas associated with higher language, cognitive, and social-emotional scores on standardized assessments (Troller-Renfree et al., 2022). In other words, relieving some of the financial burden on these moms had a measurable impact on their infants’ brains.


The take home message here is that a stressful environment doesn’t just affect children’s behavior; it gets under the skin, affecting their development even before they are born. Research suggests that helping to reduce that stress on caregivers, especially pregnant moms, is one important way we can also reduce the impact of that stress on developing children. In other words, sometimes a great way to help children is to help their moms first.


Photo by KR96/Public Domain


References


Bowers, M. E., & Yehuda, R. (2016). Intergenerational transmission of stress in humans. Neuropsychopharmacology, 41(1), 232-244.


Fields, A., Harmon, C., Lee, Z., Louie, J. Y., & Tottenham, N. (2021). Parent's anxiety links household stress and young children's behavioral dysregulation. Developmental psychobiology, 63(1), 16-30.


Frankenhuis, W. E., & Nettle, D. (2020). The strengths of people in poverty. Current Directions in Psychological Science, 29(1), 16-21.


Gee, D. G., Gabard-Durnam, L. J., Flannery, J., Goff, B., Humphreys, K. L., Telzer, E. H., ... & Tottenham, N. (2013). Early developmental emergence of human amygdala–prefrontal connectivity after maternal deprivation. Proceedings of the National Academy of Sciences, 110, 15638-15643.


McDermott, C. L., Hilton, K., Park, A. T., Tooley, U. A., Boroshok, A. L., Mupparapu, M., ... & Mackey, A. P. (2021). Early life stress is associated with earlier emergence of permanent molars. Proceedings of the National Academy of Sciences, 118(24).


Nelson, C. A., Bhutta, Z. A., Harris, N. B., Danese, A., & Samara, M. (2020). Adversity in childhood is linked to mental and physical health throughout life. bmj, 371.


Sosnowski, D. W., Kliewer, W., Valrie, C. R., Winter, M. A., Serpell, Z., & Amstadter, A. B. (2021). The Association Between Adverse Childhood Experiences and Child Telomere Length: Examining Self‐Regulation as a Behavioral Mediator. Child Development, 92(2), 746-759.


Thomason, M. E., Hect, J. L., Waller, R., & Curtin, P. (2021). Interactive relations between maternal prenatal stress, fetal brain connectivity, and gestational age at delivery. Neuropsychopharmacology, 46(10), 1839-1847.


Troller-Renfree, S. V., Costanzo, M. A., Duncan, G. J., Magnuson, K., Gennetian, L. A., Yoshikawa, H., ... & Noble, K. G. (2022). The impact of a poverty reduction intervention on infant brain activity. Proceedings of the National Academy of Sciences, 119(5).


Van den Bergh, B. R., van den Heuvel, M. I., Lahti, M., Braeken, M., de Rooij, S. R., Entringer, S., ... & Schwab, M. (2020). Prenatal developmental origins of behavior and mental health: The influence of maternal stress in pregnancy. Neuroscience & Biobehavioral Reviews, 117, 26-64.