Sunday, March 9, 2014

Is stress making our kids sick?

For years, I have been interested in how psychological factors influence our physical well-being. Luckily, technological advances in our ability to measure biological predictors of physical health have made it possible to research these associations. So far, we know that stress wears away at our physical health. Like many well known psychological findings, this is intuitive to many people. Anecdotally, I remember getting horribly sick every year after finals were over when I was in college, likely due to the stress placed on my mind and body at the end of each semester. However, until recently, we didn’t really understand how psychological stress negatively impacted the functioning of physical systems such as the immune system.

Luckily, Emma Carlsson at the Jonkoping University in Sweden and her colleagues recently published a study asking the question:

How is stress related to immune system functioning in young children?

To address this question, they recruited 26 5 year old with exposure to high stress, 26 5-year olds with no exposure to specific types of stress and no current or history of autoimmune disorders, 26 5-year olds with no stress exposure but potentially with or at risk for autoimmune disorders, and 26 5-year olds with exposure to high stress. In this study, high stress was assessed via parent report of the family’s exposure to serious negative life events, high reported parenting stress, low parent social support, and high parent worries. All of these children were administered cultures and autoantigens1, which is a substance that provokes an adaptive immune response (also known as an “antibody generator”), and the researchers took biological samples of blood, urine, and hair to measure their immune system’s response to the introduction of these immune stimulators2. One would expect a healthy system to respond to the introduction of these cultures with increased secretion of a number of cytokines and chemokines indicating that the immune system is effectively able to defend the child. In addition, some of the other clinical biomarkers are related to increased risk for the development of Type 1 Diabetes which results from the autoimmune destruction of insulin-producing B cells.

They found that the group of children with high reported exposure to these four types of psychological stress demonstrated significantly lower immune secretion compared to children in the other two groups at baseline (before administration of the cultures). They also found that children in this high stress exposure group demonstrated greater secretion of immune markers after the stimulation of the immune system compared with the other two groups. These high stress children also demonstrated increased sensitivity to diabetes-related autoantigens which may indicate risk for the development of Type 1 Diabetes.

Finally, children in the high stress exposure group had higher average cortisol levels, which is a biomarker for chronic exposure to stress or dysfunction within the body’s stress regulation system. When this system is activated by exposure to stress, the immune system is suppressed. Thus, one potential way that exposure to psychological stress may result in immune dysfunction is that these children have chronically suppressed immune systems, resulting in long-term changes in functioning. Consistent with this theory, children in the high stress group had lower baseline immune functioning compared with the other two groups.  In addition, this same group of high stress exposed children demonstrated greater secretion of the immune response, suggesting the immune system is imbalanced. These secretions, in moderate amounts have protective impact on the system, but excess exposure can lead to inflammatory conditions such as asthma and allergies. The imbalance in the system from baseline to immune response may be an indication of an inability to regulate the production of pro-inflammatory immune cells, thus increasing risk for autoimmune and inflammatory conditions.

Now, I know that got pretty complicated for a minute there, so let me try to summarize. Children who are exposed to high psychological stress have an imbalanced immune system that is more vulnerable at baseline and hyper-responds to exposure to a threat. This profile of immune system functioning may explain why children with more stress exposure are at increased risk for autoimmune and inflammatory conditions such as asthma, allergies, and Type 1 Diabetes.

Like all great research, this study is not without its limitations. For example, this study was conducted cross-sectionally, so there can be no causal interferences drawn. The children in this study were only 5-years old, with no long term follow-up so far. Thus, we don’t know how well these profiles of immune response predict the development of actual physical conditions. However, we do now that children who are exposed to abuse and trauma are more likely to have asthma, allergies, and other physical health conditions from previously published longitudinal and epidemiological studies.

So what does this mean? Stress is part of life; it’s unavoidable. Most interesting to me, is that the psychological stressors that these children were exposed to almost entirely more related to their parents’ stress, rather than their own. Now we all recognize that parent stress often contributes to child stress, but many parents take for granted how aware their children are of their daily stress, and potentially unaware of how much their personal stress is impacting the child’s health and development. So, take care of yourselves parents, so you have more resources to care for those kids. Get sleep, eat vegetables, drink water, have fun, and get support! To me, the most important thing to take away from this study is the sensitivity of the child to parent stress related to having low social support. I know a lot of new parents both personally and professionally and the first thing that suffers when the baby comes are their relationships with friends, not knowing how important those supportive relationships are to the health of your children. No one benefits when you are trying to do that alone. The good thing is that parent support comes in many shapes and sizes: family, friends, mental health services, church, and schools. You can never have too much!

Carlsson, E., Frostell, A., Ludvigsson, J., & Faresjö, M. (2014). Psychological Stress in Children May Alter the Immune Response. The Journal of Immunology, 192(5), 2071-2081.

1 For those of you that are interested, the administered cultures were tetanus toxoid and β-lactoglobulin, while autoantigens were glutamic acid decarboxylase 65, insulin, heat shock protein 60, and tyrosine phosphatase.

2 The immune response and other clinical biomarkers measured were: cytokines, chemokines, C-peptide, proinsulin, glucose, and cortisol. 

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