There is good evidence to show that stress can increase a person's heart rate, lower the immune system's ability to fight colds and increase certain inflammatory markers but can stress also raise a person's cholesterol? It appears so for some people, according to a new study that examines how reactions to stress over a period of time can raise a person's lipid levels.
This finding is reported in the November issue of Health Psychology, published by the American Psychological Association (APA). In a sample of 199 healthy middle-aged men and women, researchers Andrew Steptoe, D.Sc., and Lena Brydon, Ph.D., of University College London examined how individuals react to stress and whether this reaction can increase cholesterol and heighten cardiovascular risk in the future. Changes in total cholesterol, including low-density lipoprotein (LDL) and high-density lipoprotein (HDL), were assessed in the participants before and three years after completing two stress tasks.
Our study found that individuals vary in their cholesterol responses to stress, said Dr. Steptoe. "Some of the participants show large increases even in the short term, while others show very little response. The cholesterol responses that we measured in the lab probably reflect the way people react to challenges in everyday life as well. So the larger cholesterol responders to stress tasks will be large responders to emotional situations in their lives. It is these responses in everyday life that accumulate to lead to an increase in fasting cholesterol or lipid levels three years later. It appears that a person's reaction to stress is one mechanism through which higher lipid levels may develop."
The stress testing session involved examining the participants' cardiovascular, inflammatory and hemostatic functions before and after their responses to performance on moderately stressful behavioral tasks. The stress tasks used were computerized color-word interference and mirror tracing. The color-word task involved flashing a series of target color words in incongruous colors on a computer screen (ex. Yellow letters spelling the color blue). At the bottom of the computer screen, four names of colors were displayed in incorrect colors. The object of the task was to match the name of the color to the target word. The other task used was mirror tracing, which required the participant to trace a star seen in a mirror image. The participants were told to focus more on accuracy than on speed in both tasks.
At the follow up three years later, cholesterol levels in all the participants in the study had gone up, as might be expected through passage of time. However, individuals with larger initial stress responses had substantially greater rises in cholesterol than those with small stress responses. The people in the top third of stress responders were three times more likely to have a level of 'bad' (low-density lipoprotein) cholesterol above clinical thresholds than were people in the bottom third of stress responders. These differences were independent of their baseline levels of cholesterol levels, gender, age, hormone replacement, body mass index, smoking or alcohol consumption.
The authors found no sex differences among the participants in their cholesterol levels and response to stress. Steptoe and Brydon speculate on the reasons why acute stress responses may raise fasting serum lipids. One possibility may be that stress encourages the body to produce more energy in the form of metabolic fuels – fatty acids and glucose. These substances require the liver to produce and secrete more LDL, which is the principal carrier of cholesterol in the blood. Another reason may be that stress interferes with lipid clearance and a third possibility could be that stress increases production of a number of inflammatory processes like, interleukin 6, tumor necrosis factor and C-Reactive protein that also increase lipid production.
Even though these lipid responses to stress were not large, said Dr. Steptoe, "the levels are something to be concerned about. It does give us an opportunity to know whose cholesterol may rise in response to stress and give us warning for those who may be more at risk for coronary heart disease."