Based on health data for 500 unrelated black men over age 20 enrolled in the Howard University Family Study, researchers found those who had lived with one parent rather than two as children had higher average blood pressure readings.
The men who had grown up in single-parent households also had a 46% greater risk of developing high blood pressure, also known as hypertension."These differences in mean blood pressure and the prevalence of hypertension among men raised in two-parent households vs. single-parent households during childhood are quite significant," Debbie Barrington said.
Barrington led the study at the National Institute on Minority Health and Health Disparities with colleagues at the National Institutes of Health in Bethesda, Maryland.
Childhood living arrangements
About 1 in 3 US adults has high blood pressure, according to the Centres for Disease Control and Prevention. High blood pressure increases the risk of heart attack and stroke, which are leading causes of death.
Generally, the lower the maximum blood pressure (the top number), the better, with a reading under 120 millimetres of mercury (mmHg) considered best.
Previous studies have linked childhood living arrangements to aspects of high blood pressure, but this one is the first to examine black men a population at particular risk for hypertension.
Men who had lived with both parents as children tended to have a maximum blood pressure 4.4 mmHg lower than those who had never lived with both parents. The differences in maximum blood pressure between men raised by two parents versus one were greater than the changes produced by some common prescription blood pressure medications, Barrington said.
The men from two-parent households also tended to have a smaller difference between maximum and minimum blood pressure as the heart pumps, and a lower average pressure, all of which are usually for the better.
The gaps widened further for men who had lived with both parents between ages 1 and 12, averaging 6.5 mmHg lower maximum blood pressure readings than men from single-parent households, according to the results published in the journal Hypertension.
It might not actually be the presence or absence of parents that directly affects blood pressure, but the number of parents in the home could indicate other important childhood risk factors, Barrington said.
Children who grow up in single-parent households are more likely to experience poverty, and early childhood poverty has been linked to later health problems like hypertension, she said.
Among the study participants, "Those men who grew up in two parent households during childhood were also more likely to experience less economic hardship and subsequently less stress in early life," she said.
"Less childhood stress potentially delays the rise of blood pressure that increases with age, lowering one's risk of hypertension in adulthood. "Childhood family living arrangements might, for research purposes, be equivalent to social and economic status, Barrington said, though she did not collect economic data on the men's childhood households.
If that kind of economic background information had been taken into account, she said, the protective effect of having two parents in the home might have been smaller or might have disappeared.
'Hard-wiring' for hypertension
Research has shown that living with two parents improves the social circumstances of black American boys, increasing their academic success and employment prospects and decreasing the likelihood of drug and alcohol abuse, Barrington pointed out.
"There is substantial evidence that changes in family structures can augment environmental stressors and unmask genetic, ethnic and cultural factors in the African-American predilection for hypertension," said Richard Millis, who was not involved in the study.
To begin to translate these results to useful principles in daily life, the medical community should begin by "educating the educators", namely nurses, doctors and health professionals, said Millis, an associate professor of physiology and biophysics at Howard University College of Medicine in Washington, DC. Doctors can then help patients understand how lifestyle choices might reverse "hard-wiring" for hypertension, he said.
One interesting place to start would be to research the "critical period" of childhood between ages 1 and 12, the study authors write. Until the new results are replicated, black Americans should continue to follow Institute of Medicine recommendations for blood pressure screening and decreasing salt, fat and sugar in their diets, Barrington said.
"Our study suggests that there may be a link between childhood family living arrangements and blood pressure in black men," she said. "It does not suggest that those men who did not live with both parents during childhood are destined to have high blood pressure in adulthood."