New research presented at this year's European Congress of Clinical Microbiology & Infectious Diseases (ECCMID) taking place online (9-12 July) shows that individuals affected by mental illnesses including depression and schizophrenia experience an increased incidence of tuberculosis (TB).
TB and mental illnesses are both urgent global health priorities with a high prevalence across the world, and often co-exist. Although poor mental health is known to affect the immune system, it is not known whether mental illness plays a causal role in TB infection and an individual's risk of developing the active disease.
This study by Sally Hayward and colleagues at the Institute for Infection and Immunity, St George's, University of London, UK, in collaboration with the London School of Hygiene and Tropical Medicine, the University of Nottingham, and Columbia University, New York, examined evidence for an association between mental health and risk of developing TB to better inform clinical and public health measures aimed at tackling the disease.
The authors conducted a systematic review of research studies sourced from MEDLINE, PsycINFO, and PsycEXTRA medical databases. Criteria for inclusion were a publication date in the period 1 January 1970 to 11 May 2020, and that the study contained data on the association between mental health and risk of active TB.
The researchers screened a total of 1,546 studies, resulting in data taken from 607,184 individuals across Asia, South America, and Africa over a 50-year period. These looked at both mood disorders such as depression, as well as psychotic disorders which include schizophrenia.
The team found robust evidence from studies conducted in Asia that both depression and schizophrenia are associated with an increased risk of developing active TB. Individuals with depression were found to be between 15% and 2.6 times more likely to have TB than those without depression, while schizophrenia was associated with between a 52% increased risk and a tripling of risk of having TB.
Further analysis of data from one large study of 242,952 subjects across low and middle-income countries also found that individuals with TB were more than three times more likely to suffer an episode of depression than people without the disease.
The authors conclude: "Our data show that individuals with mental illnesses including depression and schizophrenia experience increased TB incidence and thus represent a high-risk population that could be targeted for screening and treatment."
They add: "Integrated programmes providing care for mental health and TB are needed, and interventions that tackle mental illnesses and their underlying drivers may help reduce incidence of TB globally."
Sally Hayward, lead author on the study from St George's, University of London, said: "It's clear that mental health conditions and TB often co-exist, but this study shows that mental health might play a causal role in increasing TB risk, potentially through its effect on the immune system. This underscores the importance of work to address the global burden of mental illness, and approach physical and mental health holistically."
**Note this is a special early release from the European Congress of Clinical Microbiology & Infectious Diseases (ECCMID 2021). Please credit the conference if you use this story**