Friday, July 2, 2010

Hierarchy and the Stress Response

The social determinants of health require us to think about health in a way that goes against accepted ideology. We are told diet, exercise, smoking and condoms are the factors that affect our health. While these factors are important for the health of the individual little emphasis is placed on the caring and sharing within a community. Studies show that a hierarchical society, like our own, produces a chronic stress response in the subordinate classes.

To deal with a stressful situation the body's sympathetic nervous systeminduces the "fight or flight" response. This mobilizes the endocrine system to produce the stress hormones Growth Hormone (GH), Cortisol, andnorepinephrine & epinephrine (adrenaline). An acute stress response is beneficial to our health as it prevents us from getting hit by a car (or a taxi if you live in NYC). However, chronic exposure to the stress hormones can lead to a laundry list of health problems:

  • Stress hormones antagonize the ability of insulin to reduce blood glucose thus contributes to hyperglycemia.
  • Cortisol along with norepinephrine & epinephrine play an important role in inflammation and immune homeostasis. Cortisol inhibits phospholipase A, a key enzyme in the mediation of the inflammation response. Cortisol also compromises the immune system by decreasing the number of helper T lyphocytes. An anti-inflammatory and immunosuppressant response is an essential strategy when fighting an infection suddenly is less of a priority than out running a lion. However, this has the potential to do significant harm when the body is not able to attend to an injury or infection for a prolonged period of time.
  • Cortisol and epinephrine are involved in the creation of short-term memories, however chronic exposure may damage the cells of the hippocampus and impair the ability to learn.
  • Reproductive behavior is reduced in response to stress. Cortisol inhibits the reproductive axis of the endocrine system.
  • Our muscles contract when calcium ions are released into the muscle cell. Our bones are our calcium reservoirs and cortisol increases bone resorption (break down of bone) to provide more calcium to the muscles. Again, think "fight or flight." However, too much cortisol over a long period of time leads to decreased bone density and osteoporosis.
  • Cortisol and GH are involved with lypolysis (break down of fat) thereby making free fatty acids available as energy sources. However, this fat gets redistributed around the visceral organs.This means increased abdominal fat which can lead to heart disease among other problems.
  • Cortisol also shows strong, consistent relationships with obesity factors.
  • Excessive levels of cortisol initially produces a feeling of well-being but continued exposure eventually leads to emotional lability and depression.

In order to reduce stress the common suggestions are: breathe to relax, exercise, practice mediation or yoga, sex, music, etc. However, these strategies do nothing to mitigate the stress caused by social hierarchies (with exception of sex as we will see). Subordinates in such a society have less control and routine to their daily lives. Additionally, they have less protection from unforeseen disruptions such as illness, disability or loss of income. This allows for a very stressful environment. However, those who have more friends - those who practice more caring and sharing do better at managing their stress. Friends, in a sense, are protection from life's catastrophes. The reassuring feeling to know that you have a couch to sleep on if you lose your house or you can borrow some money if you're pinched for cash helps to reduce an otherwise stressful situation. One can imagine sex is involved in building relationships with others and thus also helps to reduce stress. This was demonstrated in a study where male baboons more involved in consortships had lower basal cortisol levels than their more threatening rivals.

The next post will discuss how to reduce hierarchies and create a more egalitarian society in order to close the gap in health inequalities. Until then, be fruitful and multiply.

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