Persistent Mild Depression in Older Adults May Lower Immunity and Ability to Fight Off Disease

WASHINGTON — It is estimated that 15-57 percent of older adults experience some form of chronic depression for a period of time later in their lives, according to recent research, and this may compromise their ability to fight off infections and cancers.

Lead researcher, Lynanne McGuire, Ph.D., of John Hopkins School of Medicine and co-authors Janice K. Kiecolt-Glaser, Ph.D., and Ronald Glaser, Ph.D., of Ohio State University College of Medicine found that even chronic, sub-clinical mild depression may suppress an older person’s immune system. Those with chronic mild depression had poorer lymphocyte -T cell responses to 2 mitogens at the follow up 18 months later. And the older a person was, the poorer the immune response was to mitogens – a model for how the body responds to outside agents, like viruses and bacteria.

Reported on in this month’s Journal of Abnormal Psychology, published by the American Psychological Association (APA) is an 18-month prospective study of 78 older adults (average age of 72.5 years old) that compared those who suffer from chronic depression (22) and those who don’t (56) on their ability to generate enough white blood cells to fight off an infectious agent.

Participants were part of a larger, longitudinal study on stress and health of caregivers of adults with dementia. Forty of the participants were caregiving for spouses with dementia. And 38 of the participants were not caregivers and recruited from newspaper advertisements, church groups and other local neighborhood referrals. The non-depressed group included 25 caregivers and 31 non-caregivers and the depressed group included 15 caregivers and seven non-caregivers. Females accounted for 64 percent in both the depressed and non-depressed group.

There was no significant difference found for risk of depression between those who were married, those with more education or those at a higher income level. All the depressed participants reported clinically relevant depressive symptoms at the beginning of the study and 18 months later, said McGuire, but fewer than half of these participants met formal diagnostic criteria for depression. “In this study, it seems that it is the length of time of the depression, not the severity that is affecting a person’s immunity.”

This information along with previous research findings suggests that “depressive symptoms can exacerbate and accelerate the immunological declines that typically accompany aging. Changes in the immune response, including dysregulation of the proinflammatory cytokines and endocrine functions has been associated with depression as well as aging, especially in adults over 60,” said McGuire. Other factors in addition to aging can have a role in lowering older adults’ immunity. Lack of social support has been reported in the research as a risk factor for depression.

McGuire and colleagues postulate that age-related changes in cell-mediated immunity caused by mild depression is linked to the increased risk and severity of infections and cancer found in older adults. And these findings suggest that detection and treatment of even mild depression may be crucial for better health in older adults since the prevalence of mild depression is high in this age group.

Article: “Depressive Symptoms and Lymphocyte Proliferation in Older Adults,” Lynanne McGuire, Ph.D., John Hopkins School of Medicine; Janice K. Kiecolt-Glaser, Ph.D., and Ronald Glaser, Ph.D., Ohio State University College of Medicine; Journal of Abnormal Psychology, Vol 111, No. 1.

(Full text of the article is available from the APA Public Affairs Office or at after February 25, 2002)

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