Surprisingly, when the depression was being treated, responses to the vaccine were normalized, even when the depression treatment had not been effective in lessening the symptoms of depression.
"Among depressed elderly, treatment with an antidepressant medication such as a selective serotonin uptake inhibitor might increase the protective effects of zoster vaccine," said Irwin.
Larger studies are needed to evaluate the possible relationship between untreated depression and the risk of shingles, the study noted, along with further research to establish what mechanisms are responsible for patients' reduced immune response.
And there is a clinical side as well, Irwin noted. "Efforts are also needed to identify and diagnose depressed elderly patients who might benefit from either a more potent vaccine or a multi-dose vaccination schedule." he said.
The findings have important public health implications beyond the prevention of shingles, possibly extending to other infectious diseases, Irwin said. Because this study measured immune system T cells that were specific to the varicellazoster virus, the association may extend to T cells specific for antigens of other pathogens that cause disease in older adults, such as influenza.
If so, Irwin said, this suggests that untreated depression may identify a sub-group of elderly likely to respond poorly to other vaccines.
"While we know that psychological stress is associated with a weakened immune response to influenza vaccines in older adults, few studies have examined the association between depression and infectious disease risk, or disease-relevant immunologic endpoints, such as vaccine responses," he said.
|Contact: Mark Wheeler|
University of California - Los Angeles