Understanding the have-knots: The role of stress in just about everything

There is now evidence that another trait associated with success-striving in the modern world — persistence — may also lead to health problems in some circumstances. When goals are not readily attainable, the inability to detach from them may produce frustration, exhaustion, rumination on failures, and lack of sleep. These in turn activate harmful inflammatory responses that can lead to illness and lowered immunity.

Studies also have shown that optimistic people have lower incidence of heart disease, better prognosis after heart surgery, and longer life.

The effects of a positive attitude on immunity were shown in a study by Sheldon Cohen, Carnegie Mellon University, and his colleagues, in which individuals were exposed to a cold virus in a laboratory setting and watched over six days. Those with a positive emotional style were less likely to develop colds than were individuals with low levels of positive affect. Positive affect was also found to be correlated with reduced symptom severity and reduced pain.

Personality and environmental factors are not the whole story when it comes to stress.

The next frontier of stress research is the rapidly growing field of behavioral genetics. Modeling the interaction of genetic and environmental influences is no longer a matter of weighing the relative input of nature and nurture. The two intertwine in subtle and complicated ways, with environments affecting gene expression, and vice versa, throughout life. Thus, the current watchword is “stress-diathesis” models, in which environmental stressors have varying impact on individuals due to preexisting inherited vulnerabilities.

One major advance in this area was the discovery by Avshalom Caspi, University of Wisconsin, and his colleagues of a link between stress sensitivity and a particular gene called 5HTTLPR. Findings suggest certain genetic makeup seems to increase the risk for a serious illness through the mechanism of increased sensitivity to stressful occurrences.

Nathan Fox, University of Maryland, and his colleagues subsequently reported that children with two short alleles of the 5HTTLPR gene, whose mothers also reported receiving low social support, were more likely to show behavioral inhibition (fearfulness and a tendency to withdraw) at age 7. Those receiving high support did not show the tendency, and those with the long alleles but receiving low support also appeared “protected” by their genetic makeup.

Genetic predisposition to stress sensitivity may in some cases become a self-fulfilling cycle. Fox and colleagues found that some very behaviorally inhibited children were regarded by their mothers as hard to soothe and received less care and sensitivity as a result; this in turn tuned up the child’s sensitivity to stress. In the model Fox and colleagues propose, genetically influenced temperament in early childhood influences the quality of caregiving children receive, which in turn shapes a child’s attention bias to threat.

But look on the bright side: The newly refined science of stress could lead to new drug therapies that can control stress or inhibit its effects on health. Also, depression and anxiety are not only results of stress, but also causes, and existing therapeutic and medical treatments for these conditions can help change how people perceive threats, put their life challenges in context, and cut stressors down to manageable size. The cycle doesn’t have to be vicious, in other words.