Decline in lower limb function is common in older people, and worsening gait is associated with increased risk of dementia and death. However, factors contributing to gait difficulties in older persons are not well understood. A study by researchers at Rush University Medical Center suggests that higher blood pressure may be one factor associated with a decline in walking ability in later life. The research, by Dr. Raj Shah and colleagues at the Rush Alzheimer's Disease Center, is published in the August 2006 issue of the Journal of Gerontology: Medical Sciences, the scientific journal of The Gerontological Society of America.
Researchers recruited 888 older Catholic clergy without dementia or Parkinson's disease who are participating in the Religious Orders Study. At baseline, blood pressure was measured, the presence of vascular diseases and diabetes was recorded, cognitive function was assessed, and medications were inspected.
At baseline and subsequent annual visits, gait and balance were assessed using performance-based tasks, such as the time and number of steps taken to walk 8 feet, the time to sit up and down five times, the number of steps off the line during an 8-foot heel-to-toe walk, and a comparison of ability to stand with eyes open and eyes closed.
Participants completed a mean of nearly eight annual evaluations with a high rate of follow-up. Controlling for age, education, and gender, the study found a 10mmHg increment in systolic blood pressure was associated with greater decline in lower limb function. On average, lower limb function declined 28.7 percent faster in persons with a systolic blood pressure of 160 mmHg than in persons with a normal systolic blood pressure of 120 mmHg.
"After memory loss, the biggest concern of older individuals is loss of mobility," said Dr. Raj Shah, medical director of the Rush Alzheimer's Disease Center's Memory Clinic. "If high blood pressure is impacting gait, it is a risk factor that possibly can be controlled in order to help people stay active as they age."
The study wasn't able to determine why blood pressure is impacting gait. However, Shah notes it may partially be related to stroke. The study found that diabetes, vascular diseases, or cognition did not change the association of blood pressure and lower limb function. Although baseline clinical stroke had no effect on higher blood pressure being associated with lower limb function, when researchers took out individuals that developed stroke during the study, the relationship between blood pressure and mobility wasn't as strong.
Further studies examining lifelong blood pressure measures will be necessary to fully explore why there is a link between blood pressure and lower limb function. In addition, Shah hopes clinical trials will study if the treatment of blood pressure improves walking abilities.
"Gait difficulties are very common in older adults. We hope our research will lead to better treatment options and to preventive measures that will help older adults maintain active, independent lives ," said Shah.
The investigators are part of the institution's Rush Alzheimer's Disease Center, headed by Dr. David Bennett. The AD Center is one of 30 across the U.S. supported by the National Institute on Aging (NIA) at the National Institutes of Health to study and care for Alzheimer's patients.
The Rush researchers are extremely grateful for the remarkable dedication and altruism of the volunteers participating in the Religious Orders Study, a longitudinal, clinical-pathologic study of older persons without dementia The research was supported by grants from the National Institute on Aging, which leads the Federal effort to support and conduct basic, clinical, and social and behavioral studies on aging and on Alzheimer's disease.
Contact: Kim Waterman
Rush University Medical Center