Higher blood pressure is linked to depression, but only in people with a family history of hypertension, a new study finds. People whose parents did not have high blood pressure did not show the same association.

The roots of the relationship between high blood pressure and depression lie in a mix of genetics and social factors with the family, says Karen M. Grewen, Ph.D., of the department of psychiatry at the University of North Carolina at Chapel Hill. “The impact of parental hypertension on future risk [is] most likely the result of shared genes, learned behaviors, shared environments, or various combinations.”

The study appears in the January / February issue of the journal Psychosomatic Medicine.

Hypertension is a major risk factor not only for heart disease but also for stroke and kidney disease. Doctors have known for some time that depression may presage heart-related disease and death in both healthy people and those who have had heart attacks. But the connection of depressive symptoms to parents’ blood pressure status had not been documented.

How depression influences heart disease is not entirely clear. The connection may have both behavioral and biological components. People who are depressed may act in unhealthy ways, like smoking or not taking their medicine, which leads to heart disease. Depression may also work more directly within the body by triggering or inhibiting substances that endanger the heart, either immediately or over time.

The researchers gave 314 volunteers a standard test for depression and measured their blood pressure for 24 hours using a wearable monitor. Participants whose mother or father or both had high blood pressure were listed as having a family history of the disease.

Participants whose parents had hypertension had significantly higher systolic blood pressure (the “top” number in blood pressure measurements) and higher diastolic blood pressure (the “bottom” number). They also had a higher body mass index, a measure of obesity, although both groups fell into the “overweight” category.

Using the portable blood pressure monitor revealed the connection between family history, depressive symptoms and high blood pressure, Grewen says, while conventional, in-office measurements did not.

Another observation solidified that connection. The relationship between depressive symptoms and blood pressure varied progressively depending on whether one, both or neither of their parents had high blood pressure. The association was weakest for those with no hypertensive parent, moderate for those with one such parent and strongest for those with two parents who had high blood pressure.

About 10 percent of the subjects with no family history had diagnosed hypertension, as did 20 percent of those with a family history. However, overall results were unchanged even when these subjects were excluded from the analysis.

Because findings were the same for subjects with and without high blood pressure, the pattern of depression and family history may precede development of overt hypertension, Grewen says.

Future research, she says, might look at assessments of depressive symptoms over a longer time while also considering family history of high blood pressure. But other steps could be taken immediately to alleviate the long-term risk posed by high blood pressure. Treating depression not only relieves suffering and improves quality of life, but may also lower heart disease risk.

“Depressive symptoms not considered serious enough to warrant a mental health problem may increase blood pressure more consistently in those with familial or genetic risk factors,” Grewen says. “Thus, behavioral interventions that reduce depressive symptoms may be more effective in lowering risk of hypertension in these genetically prone people.”

This research was supported by grants from the National Institutes of Health.

Health Behavior News Service: (202) 387-2829 or www.hbns.org.

Psychosomatic Medicine: Contact Victoria White at (352) 376-1611, ext. 5300, or psychosomatic@medicine.ufl.edu. Online, visit www.psychosomaticmedicine.org.

Aaron Levin