TB Risk Increased in People With Mental Illness

By Megan Brooks

July 08, 2021

NEW YORK (Reuters Health) - Individuals with depression or schizophrenia appear to be at increased risk for tuberculosis (TB), according to published studies.

While the mechanism remains unclear, "it is possible that mental illnesses are altering the immune system in such a way as to increase TB risk," PhD student Sally Hayward of the Institute for Infection and Immunity at St George's, University of London told Reuters Health by email.

"We know that mental-health disorders modulate the immune system (including increasing risk of infections from the common cold to HIV), and that the immune response underpins whether TB infection leads to active disease," she explained.

In their systematic literature review, Hayward and colleagues screened 1,546 studies that contained data on the association between mental health and risk of active TB. Altogether, they synthesized data on more than 607,000 individuals across Asia, South America and Africa over five decades.

There is "robust" evidence from retrospective cohort studies conducted in Asia that both depression and schizophrenia can increase the risk of active TB, according to a poster presented at the virtual European Congress of Clinical Microbiology and Infectious Diseases (ECCMID).

For depression, hazard ratios ranged from 1.15 (95% confidence interval, 1.03 to 1.28) to 2.63 (95% CI, 1.74 to 3.96). For schizophrenia, estimates ranged from a HR of 1.52 (95% CI, 1.29 to 1.79) to a relative risk of 3.04, the study team reports in their conference abstract.

The retrospective data is supported by evidence from cross-sectional studies. For example, one large study of nearly 243,000 individuals across low- and middle-income countries found a greater than three-fold increased likelihood for a depressive episode in those with TB versus those without the disease (odds ratio, 3.36; 95% CI, 3.01 to 4.50).

"The evidence as a whole supports an association between mental health and TB risk," the researchers write in their abstract.

"It is well known that mental illnesses and TB often co-exist, but this is the first time that the evidence on whether mental disorders increase TB risk specifically has been brought together," Hayward told Reuters Health by email.

"Those suffering from mental illnesses - especially depression and schizophrenia - are at high risk of TB and should be targeted for case-finding and treatment," she said. "Services for mental health and TB should be brought together to provide holistic care for the two conditions. Interventions tackling mental illnesses may help reduce TB incidence globally," she added.

Hayward is currently leading a research project that will be the first to look at whether mental illness influences the immune response to TB.

SOURCE: https://www.eccmid.org/ European Congress of Clinical Microbiology and Infectious Diseases, held online July 9-12, 2021.

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