- Household instability changes developing brains in distinct ways. Tweet This
- New research by Felicia Hardy and colleagues explains how the allostasis created by household instability before age 5 increases the risk of depression by age 21. Tweet This
- What actually changes when children experience household instability early in life? The brain’s structural network efficiency, per a new study. Tweet This
Neuroscientists have pushed forward knowledge about how the body reacts to stress in recent decades. In particular, they now understand that only a limited number of physiologic variables, such as pH, body temperature, glucose levels and oxygen tension, must remain in homeostasis, i.e., within set and narrow limits. In contrast, there is much in our physiology that can achieve allostasis, i.e., new stasis. This means that the things that happen in our lives can change our bodily systems and how they function.
New research by Felicia Hardy and colleagues published in June in Developmental Cognitive Neuroscience explains how the allostasis created by household instability before age 5 increases the risk of depression by age 21. What makes this new work so different from social science research linking childhood instability with adverse outcomes is that Hardy’s team was able to describe how household instability changes children’s brains. That is, they were able to describe the allostasis that is created in children’s brains as an adaptation to household instability, and how that allostasis is more vulnerable to depression in adulthood than brain development associated with childhood stability.
The notion that allostasis is a blessing that comes with costs is not at all new. Life history strategy theory posits that stress-induced adaptions—such as an increased pace of development early in life—can be helpful in the short-run, while also posing long-term health consequences. Allostatic load refers to the wear-and-tear on the body that results from achieving allostasis: a new stasis is better than not adapting to stress, but it is not cost-free.
So, what actually changes when children experience household instability early in life? The brain’s structural network efficiency. That is, the structural networks of adolescents who had undergone early household instability were more efficient than those of others. At first blush, that sounds pretty good: who wants a less efficient brain? But the authors explain that early maturation of neural structures may solidify connections in ways that limit opportunities for subsequent enrichment, potentially increasing susceptibility to psychopathology. They specifically show that greater global efficiency measured from dMRI data obtained in adolescence is related to increased depressive (but not anxious) symptoms during young adulthood. It’s one of those adaptations that carries a cost. Other recent research has documented other brain-level adaptations in the short run to inconsistent mothering, but the work published by Hardy et al. is the first to describe long-run brain changes. Their multi-year study of the child’s environment likely captures the accumulation of stress resulting from unstable environments.
What do they mean when they say childhood household instability? Unfortunately, they mean things that happen to lots of kids: residential moves, changes in household composition (people moving in or out of the child’s household), and caregiver transitions in the first 5 years. A few of the children in their study experienced all of these more than once, and a few had none at all: most experienced some degree of household instability, and the researchers tested whether the degree mattered. Importantly, their study was able to demonstrate that other influential stressors (e.g., harsh parenting, neglect, food insecurity) have unique neural correlates for mental health. That means that other stressors matter, but that household instability is qualitatively different: it changes developing brains in distinct ways.
Demonstrating that different stressors affect growing children’s brains in different ways is important for underlining a more basic truth: what happens to people changes them.
In my experience, social scientists have an ambivalent relationship with biology. On the one hand, we tend to downplay its importance: we contend that almost all of our reality is social construction, i.e., that events have the meaning that we are socialized to assign to them (or the meaning that others assign to them, which we are socialized to accept). On the other hand, we embrace the reality that social forces can “get under the skin” and have important biological consequences. These perspectives are not inherently at odds, but they can be in some cases.
I think the tension becomes apparent when considering the implications of work like Hardy’s that links childhood household instability to adolescent global network efficiency to adult depression. Is it plausible that growing children adapt to household instability with accelerated brain maturation because that is what society teaches them to do? Or that the adult depression associated with accelerated brain maturation is learned behavior? My questions reveal my bias: I believe household instability is bad for kids, and I’m not surprised by advances in neuroscience that show us how household instability gets under the skin (and under the skull).
The scientist authors suggest that their results could inform interventions that promote household stability during early childhood to benefit long-term development of mental health and well-being. Unfortunately, social scientists already know that it is very difficult to design interventions that reduce residential moves, household composition changes, and caregiver changes. Still, I think that if we recognize that these things are inherently important to limit—rather than assuming their importance is socially defined—we could do better in reaching for the authors’ lofty goal.
Laurie DeRose is a senior fellow at the Institute for Family Studies, Assistant Professor of Sociology at the Catholic University of America, and Director of Research for the World Family Map Project.