Childhood Stress: a Risk Factor for Adult Heart Disease?
Heart disease is strongly associated with life in modern societies. There are several possible reasons for this. First, people who live in technologically advanced societies live longer because of better standards of hygiene and access to medical services. However, the same reason why a person may live longer also exposes them to greater risk of heart disease. This is partly due to the fact they are more prone to smoking, drinking alcohol, exercising less and become obese. There is of course another difference and this relates to the degree of stress that people are exposed to when living in modernized societies.
There is now a fairly comprehensive body of research pointing to the association between stress and heart disease. The risk factors are varied and include the stress that derives from job dissatisfaction, responsibility, major life events, shift work and high work loads, to name just a few. Stress increases the presence of catecholamines and corticosteroids in the body. Over time, this promotes atherosclerosis (hardening of the arteries) and hypertension (high blood pressure). Physiological change mixed with behavioral factors (smoking, drinking, etc) then becomes a potent combination.
But what exactly is life stress and when should we start to take notice of it? Recent research to emerge from the Medical College of Georgia, published online in Hypertension, suggests early life stress could be a risk factor for cardiovascular disease in adulthood. The research news website ScienceDaily.com quotes corresponding author Dr. Jennifer Pollock:
"We think early life stress increases sensitivity to a hormone known to increase your blood pressure and increases your cardiovascular risk in adult life."
Using a well established technique for the study of chronic stress, rat pups were separated from their mother for three hours a day over the period of a fortnight. During this time the rat pups showed none of the risk signs normally associated with cardiovascular disease. As adults the situation changed dramatically. To simulate the effect of stress, adult rats including those who had been separated as pups from their mothers, were given the hormone angiotensin II. Angiotensin II is a natural substance in the body. It has the effect of narrowing blood vessels to make the heart work harder when necessary. It also regulates blood vessel growth and inflammation, both of which are implicated in cardiovascular disease. In rats that had spent time being separated from their mother, rapid increases in blood pressure and heart rate were recorded - all key risk factors for cardiac disease. After just a few days the early stress rats had blood pressure nearly twice as high.
Previous studies have shown that many adults with ischemic heart disease (reduced blood supply) have a history of adverse childhood events such as abuse or parental loss. According to Dr. Pollock, this study is the first time the chronic stress model has been used to measure cardiovascular impact.
The next step is to discover the mechanism that translates early life stress into cardiovascular risk. One of the most likely mechanisms is a change at the genetic level due to stress hormones. Psychological studies suggest that females are less affected by early life stress which perhaps points to the protective mechanism of certain female hormones.
Medical College of Georgia (2010, February 10). Early life stress may predict cardiovascular disease. ScienceDaily. Retrieved March 5, 2010, from http://www.sciencedaily.com/releases/2010/02/1000209183236.htm