The relationship between mental health, immune function, and tuberculosis risk among migrants

Tuberculosis (TB) remains an urgent global health priority, with 1.6 million deaths worldwide in 2021. The biology of TB infection and disease is well-understood, and the association between TB and poverty has long been recognised. However, biological and social lines of enquiry have proceeded largely independently. This project bridges this research gap, bringing together the knowledge and methods of social and biomedical disciplines to gain a truly interdisciplinary understanding of TB.

Specifically, this project explores the relationship between mental health, immune function and TB risk among migrants. There is evidence that psychological stress and poor mental health can influence immunity and infectious disease risk. However, this relationship has not been elucidated for TB. This is despite evidence that, as a disease of poverty, TB is associated with various chronic psychosocial stressors and mental disorders.
My research unpicks the mechanisms behind these associations in migrant populations. In the UK, TB rates are 15 times higher in migrants compared with the UK-born. Migrants may be exposed to various psychosocial stressors along the migration trajectory: before, during and after migration. This study will explore whether such psychosocial stressors could influence mental health, immune function and therefore contribute to migrants' increased TB risk.

This study utilises a mixed methods approach to meet the following objectives:
1) To synthesise existing evidence on the relationship between mental health and TB risk through a systematic literature review
A systematic review was conducted, searching bibliographic databases for original research on the association between mental health and TB incidence. Data were extracted using a standardised form, and studies were critically appraised using recognised checklists. The findings were synthesised narratively, by type of mental illness.
2) To explore the relationships between migrant status, TB risk, and mental health through secondary analyses of large European and national databases
Epidemiological patterns of TB among migrants in Europe were explored in the European Centre for Disease Prevention and Control's TESSy database, focusing on patterns of extrapulmonary TB. In addition, the relationships between mental health, TB, and migrant status were examined in a Danish population-based cohort of migrants and matched controls.
3) To conduct a qualitative study to understand experiences of stress in migrant TB populations
In-depth interviews were carried out with migrants with TB disease at St George's Hospital, to understand their experiences of stress in relation to pathways of migration, TB diagnosis and treatment. Data collected were analysed qualitatively using thematic analysis techniques.
4) To conduct a cross-sectional study to examine the relationships between psychosocial stress, mental health, biomarkers of immunity, and TB status

A cross-sectional study was carried out among TB patients at St George's Hospital. Data were collected on a) psychosocial factors and mental health using questionnaire tools, and b) immune function, using blood samples to examine biomarkers of immunity associated with TB infection/disease. The data collected were analysed quantitatively.

Through this project I have developed a diverse set of interdisciplinary skills bridging biological and social sciences, including quantitative analysis of large datasets, qualitative methods, epidemiological study design, and laboratory techniques.