Recently an article in the New York Times caught my eye. It was about something called “toxic stress” and its effect on children. Exposure to adverse childhood experiences (ACE), like abuse, neglect, and domestic violence, has long term impacts on a child’s psychological and physical well-being. These negative experiences can induce what researchers at the Center on the Developing Child at Harvard University call a “toxic stress response”. Before I go much further into what I found to be particularly interesting in the article, I’ll give a brief overview of the stress response system.

The stress response system involves the central nervous system, the body’s endocrine (hormone) system, and a network of chemical messengers. Environmental and physical stressors cause a cascade of events to happen within these biological systems. One important final chemical messenger that is released is cortisol. This messenger attempts to bring the body back to homeostasis by redistributing energy to areas of the body that needs it the most (like the brain and heart) and away from organs that don’t need it (like the digestive tract). Stress in little dosages are essential for healthy development. When the stress response system is overtaxed, like in the cases of ACE, cortisol has a negative effect to the body. It suppresses the immune system and can actually change the neurobiology of the brain. This affects functions like memory and concentration. Critically, stress can also influence risk for a variety of psychological disorders related to anxiety and depression.

And for children, the long range effects of stress on a developing systems are especially deleterious for psychosocial outcomes. According to the NY Times article, toxic stress can increase risks for , drug abuse, suicide, and poor academic performance. One way that stress can produce physical and psychological influences is by activating and deactivating coding segments of DNA (i.e. influencing gene expression). It’s fascinating that stress–an invisible force–is capable of all that. Stress really highlights gene-environment interaction.

The interesting part of the article was that the quality of relationship between the parent and child is a highly protective factor against the adverse effects of stress. This parallels a lot of what we know about maternal care and the stress response in rodent models. Stress neurobiology is shaped by the social environment experienced by young organisms. In infant rats (called pups), that is largely comprised of the amount of licking and grooming provided by its mother. Highly responsive maternal care promotes a less reactive stress system that is more resilient to challenges. The positive effects can also span generations.

Pups also go through a phase of hypo-responsivity to stress during a sensitive period for learning odor preferences related to attachment. This prevents pups from learning an aversion to the mother during rough handling in the nest (e.g getting stepped on or knocked around). There is evidence that similar period of hypo-responsivity is present in humans as well. In the context of the NY Times article, I cannot begin to imagine how much worse ACE would be without this protective buffering in place.

A large portion of the article was devoted to explicating a community-based program called Child First, that helps to foster home-based parent guidance and child-parent psychotherapy. And I agree, like the rodent models, parents who are receptive to their child’s psychosocial needs can have profound influences on wellbeing. More research on ACEs and protective factors is critical for the continued development of community-based programs aimed at preventing psychological problems associated with stress. Given that, I’m really looking forward to the followup to this NY Times article by David Bornstein as part of Fixes, a column that explores solutions to major social problems.