March 10, 2000 (Minneapolis) -- Elderly patients with low blood pressure may be more likely to have symptoms of depression, according to a study published recently in the Journal of the American Geriatrics Society. While the study did not determine why the two conditions are linked, its authors suggest a revisiting of the current thinking that lower is better.
Although physicians' main concern has been high blood pressure, this study shows that problems can also be associated with low blood pressure, co-author James S. Goodwin, MD, tells WebMD. "We ... have shown that there is indeed a group of symptoms associated with low blood pressure in the elderly," says Goodwin, director of the Sealy Center on Aging at the University of Texas Medical Branch in Galveston.
The findings, though, do not suggest that patients with both depression and low blood pressure would be helped by having higher blood pressure, Goodwin says. "We have no safe way of raising blood pressure. Most important, we don't know that raising these patients' blood pressure would make them feel better," he says.
The authors based their conclusions on in-home interviews of more than 2,700 Mexican Americans who were 65 and older. The patients' blood pressures were taken twice at points during the interview, and interviewers recorded all medications they had taken during the previous two weeks. The investigators found more evidence of depression in those who had a systolic blood pressure -- the top number in a blood pressure reading -- of less than 120 mmHg or a diastolic blood pressure -- the bottom number in a reading -- of less than 75 mmHg.
Depression symptoms were measured by a questionnaire consisting of 20 statements. Responses received scores ranging from 0 for answering "rarely or none of the time" to 3 for "most or all of the time." Scores of 16 or more indicated the presence of depressive symptoms.
Patients with low blood pressure averaged about three points higher on the depression questionnaire than those with normal blood pressure. Interviewees who had low blood pressure were also at greater risk of having depression scores of 16 or greater. "Patients with low blood pressure also scored lower on self-esteem and ... self-reported health and reported more days waking up feeling tired," the authors write.
The link between low blood pressure and depression symptoms is not well understood, says Goodwin. This study "by no means proves that low blood pressure causes those symptoms. Indeed, the opposite case is just as likely, that people with underlying illness may have both low blood pressure and feel bad."
Low blood pressure can be a problem for elderly patients, but is frequently unrecognized, Roy Freeman, MD, tells WebMD. "Patients should be aware of [low blood pressure] problems such as dizziness and light-headedness, as well as less obvious symptoms such as weakness, fatigue, [difficulties in thinking], and depression," he says. "Although low blood pressure in general is good, it should not be too low."
Freeman, who was not involved in the study, is a low blood pressure expert and an associate professor of neurology at Harvard Medical School in Boston, where he is a staff physician at Beth Israel Deaconess Medical Center.
- New research shows that elderly patients with low blood pressure are more likely to have symptoms of depression.
- Researchers do not know whether low blood pressure causes depression, or whether some other illness causes both conditions, and caution that attempting to raise blood pressure is unsafe.
- Low blood pressure is a frequently unrecognized problem that can cause other symptoms such as dizziness, weakness, and fatigue.