Lack of Siblings Increases Blood Pressure Risk

BUFFALO, N.Y. -- Being an only child increases your risk for high blood pressure, according to a study by researchers at the State University of New York at Buffalo.

Focusing on the relationship between the presence or absence of siblings and hypertension in 1,472 white adults, it found that the mean systolic and diastolic blood pressure and prevalence of hypertension were higher in those with no siblings, compared those with siblings.

In the case of systolic blood pressure and prevalence of high blood pressure in both sexes and diastolic blood pressure in men, the differences were statistically significant, Maurizio Trevisan, M.D., and colleagues reported in a letter in The New England Journal of Medicine.

The researchers said "the reasons for the strong cross-sectional association with systolic blood pressure and hypertension in our study can only be speculated on at this time."

They added, "Further research is needed to confirm these findings and to explore the nature of this association."

The University at Buffalo study focused on 676 men and 796 women ranging in age from 20 to 70 who participated in a survey involving a random sample of Buffalo households.

"The absence of siblings," the UB researchers wrote, "has been associated with a number of psychological characteristics (e.g., reduced sociability and need for social support, greater need for achievement, and Type A personality). It has also been hypothesized that these psychological traits are associated with an increased risk of coronary heart disease and hypertension. Other factors not examined in this study must be considered as possible confounders of the observed association between the absence of siblings and high blood pressure (e.g., the reasons for the absence of siblings, a family history of hypertension, the presence of a broken family, and lifestyle)."

Participants in the study were similar with regards to indicators of social activity such as participation in clubs, regular church attendance and size of household, according to the researchers.

They noted that "the subjects without siblings tended to smoke more than those with siblings. Heavy drinking, a well-known risk factor for hypertension, has often been found to be related to heavy smoking. Unfortunately, no data are available on either the family history of hypertension or participants' drinking habits."

Also working with Trevisan, associate professor of social and preventive medicine and acting chair of the UB Department of Social and Preventive Medicine, were Vittorio Krogh, M.D.; Linda Klimowski, Susan Bland and Warren Winkelstein, M.D.