Researchers measured the income and years of education for 95 men and 98 women, and then tested their urine and saliva for stress hormones. Cohen and his co-authors found that the lower the income and education levels, the higher the levels of three stress hormones: epinephrine, norepinephrine and cortisol. This finding was independent of race, age, gender or body mass index.
The study also found that the lower peoples' incomes and education levels were, the more likely they were to smoke and skip breakfast. (Eating breakfast is an indication of good health habits.) They were also less likely to have diverse social networks, which are known to relate to better health. All these factors contributed to increased stress hormone levels, with smoking accounting for 63 percent of the elevated hormone levels in the low-income and low-education participants.
"The study does not have to do with poverty, per se," Cohen said. "What we have found is a graded association, where those with highest levels of income and education show the lowest levels of stress hormones, those in the middle show higher levels, and those at the lowest end show the greatest levels."
The paper was co-authored by William J. Doyle, a professor in the Department of Otolaryngology at the University of Pittsburgh School of Medicine and Children's Hospital of Pittsburgh; and Andrew Buam, a professor of psychiatry at the University of Pittsburgh School of Medicine and the University of Pittsburgh Cancer Institute.
Journal
Psychosomatic Medicine