NEW YORK, Mar ’99- The chronic stress of caring for an ailing loved one can reduce the body’s ability to fight off illness, researchers conclude.

Dr. Paul J. Mills of the University of California, San Diego, and colleagues have found “functional immune deficits in elderly caregivers of patients with Alzheimer’s disease.” They published their report in the March issue of the journal Psychosomatic Medicine.

Previous research demonstrated that psychological stress has a detrimental effect on immunological function. In this study, the authors measured immune system markers in the blood of 41 elderly men and women caring for spouses suffering from Alzheimer’s disease. Ten of these individuals were classed as highly vulnerable to stress — rarely receiving a break from attending to their loved one’s needs around the clock.

Mills and colleagues were especially interested in blood levels of CD8 and CD4 T lymphocytes — roving white blood cells that help rid the body of invading pathogens. Activation of these cells “is generally accompanied by a shedding of (a specific protein called CD62L),” according to the report.

The investigators report that “vulnerable caregivers had 60% fewer” active CD8 T cells, and “significantly fewer” active CD4 T cells compared with less-stressed caregivers.

The researchers speculate that chronic elevated levels of circulating epinephrine, a stress hormone, inhibit the shedding of CD62L from these immune cells leading to a decreased number of these cells in the circulation.

A deficit of active T cells would leave the stressed caregiver more open to infection and illness. Indeed, Mill and colleagues note that “in this study, the vulnerable caregivers reported that their illnesses lasted three times longer than the nonvulnerable caregivers.”

Previous reports have also found that stressed caregivers have higher rates of hypertension, hospitalization, poorer immune responses to vaccination, and slower wound healing compared with their unstressed peers.

SOURCE: Psychosomatic Medicine 1999;61:168-174