Depression in older people may increase their risk for disability. This study provides evidence that depression in a nondisabled older person significantly increases risk for daily life and/or mobility disability. A small part of depression's effect on subsequent disability can be explained by lowered physical activity and fewer contacts with relatives and friends.
Many studies have shown that depressed older people have more physical disabilities then their peers without depression. However, most of these studies used a select sample and did not exclude people with disabilities. These studies offer the possibility that disability is a cause rather than a consequence of depression.
The researchers here studied people in East Boston, Massachusetts; two counties in Iowa; and New Haven, Connecticut. They started with a total of 10,294 people, then excluded people with disability, those who later died, and those who did have completed survey information.
Of the 6,247 left, the researchers measured depression with the Center for Epidemiological Studies Depression Scale. It measured depression that people reported during a past week.
For six years, the researchers asked about depression and disability in daily life and in mobility. The severity of the disease was not measured.
At the study end, the participants had an average age of 72.8 years. The majority (58.7%) were female; and 43.7% had fewer than nine years of education.
Results showed that depressed people were slightly older, tended to more likely be female, were less educated, and had lower incomes than those without depression. Those reporting depression were less physically active and more likely to be unmarried. They also had fewer close relatives or friends.
Those who were more depressed developed more daily life disability, 36.1% compared to the 23.9% of the nondepressed. Also, 48.3% of the nondepressed and 67.3% of the depressed persons developed mobility disability.
Why does depression increase the risk for disability? Lack of physical activity was the strongest reason. Other poor health behavior did not differ much between the depressed and nondepressed.
Having fewer close contacts also increased risk for disability. People with fewer close contacts may receive less economic, emotional, or other support that may increase their risk of worsened physical functioning. Without friends and relatives, depressed people also may not be prompted to seek medical attention, which can cause a decline in physical health.
Symptoms of depression such as fatigue and pain also may affect physical disability. Depression itself can adversely affect endocrine, neurological, and immune processes. This enhances susceptibility to disease and neuromuscular malfunctioning.
The study found that arthritis and angina had the strongest connection with depression. Stroke, cognitive impairment, and hearing problems were more common in the study's depressed people and more associated with increased risks for disability.
Identifying depression as a risk factor for disability in old age is important. Clinicians and family members need to be alert to depression's symptoms to prevent possible disability. #14
Penninx, B.W.J.H., Leveille, S., Ferrucci, L., van Eijk, J. T. M., & Guralnik, J. M. (1999). Exploring the effect of depression on physical disability: Longitudinal evidence from the established populations for epidemiologic studies of the elderly. American Journal of Public Health 89(9), 1346-1352.
Copyright. The Rehabilitation Research and Training Center on Independent Living.