Mental health has been reported to affect response to illness; now, a new UCLA study has found that untreated depression can reduce the response to shingles vaccine. The findings are of particular importance to seniors who are susceptible to the painful condition. They published their findings in the current online edition of the journal Clinical Infectious Diseases.
Shingles is a painful, blistering skin rash that can last for months or even years. It’s caused by the varicella-zoster virus, the same virus that causes chickenpox. It is thought to strike more than a million individuals older than 60 each year in the US. Every year, health officials urge individuals 50 and older to get vaccinated against the herpes zoster virus. The vaccine boosts cell-mediated immunity to the virus and can decrease the incidence and severity of the condition
Lead study author Dr. Michael Irwin, a UCLA professor of psychiatry, and colleagues have found a link between untreated depression in older adults and decreased effectiveness of the herpes zoster vaccine. In a two year study, the researchers measured the immune response to shingles vaccination among 40 subjects aged 60 or older who suffered from a major depressive disorder, then compared these responses to similar levels in 52 control patients matched by age and gender. Measurements were taken at the beginning of the study, and then at six weeks, one year, and two years after the patients received either the shingles vaccine or a placebo.
The investigators found that depressed patients not being treated with antidepressants showed a weaker immune response to the varicella-zoster virus; therefore, they were less able to respond to the shingles vaccine. These findings were compared to patients who either were not depressed, or were suffering from depression but receiving treatment with antidepressants. Dr. Irwin explained that the findings suggest that patients with untreated depression were “poorly protected by the shingles vaccination.”
Of interest, when the depression was being treated, responses to the vaccine were normalized even when the depression treatment had not been effective in lessening depression symptoms. “Among depressed elderly, treatment with an antidepressant medication such as a selective serotonin uptake inhibitor might increase the protective effects of zoster vaccine,” explained Dr. Irwin.
The investigators note that larger studies are needed to evaluate the possible relationship between untreated depression and the risk of shingles. In addition, further research should be done to establish what mechanisms are responsible for patients’ reduced immune response. Dr. Irwin noted that clinical factors need to be evaluated. He explained, “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.”
The findings also have important public health implications beyond the prevention of shingles, possible extending to other infectious diseases, said Irwin. Because this study measured immune system T-cells that were specific to the varicella-zoster virus, the association may extend to memory T-cells specific for antigens of other pathogens that cause disease in older adults, such as influenza. If so, he said, this suggests that untreated depression may identify a subgroup 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,” said Dr. Irwin. He added, “Few studies have examined the association between depression and infectious disease risk, or disease-relevant immunologic endpoints, such as vaccine responses.”
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