INTRODUCTION:
By controlling infectious and chronic diseases, public health initiatives in Nigeria and other low- and middle-income countries (LMICs) have significantly increased survival. However, emerging evidence indicates that disease processes and management techniques may have significant but underappreciated effects on mental health. Despite their consequences for long-term health and social functioning, these mental health effects are still not well incorporated into standard disease control frameworks.

METHODS:
This study offers a narrative literature review that summarises peer-reviewed evidence on illnesses that are common in Nigeria and other LMICs, such as epilepsy, tuberculosis, malaria, and HIV infection. The review concentrated on the biological, psychological, and health-system factors that connect mental health outcomes like depression, anxiety, post-traumatic stress disorder, and cognitive impairment to disease and disease control approaches.

RESULTS:
Adverse mental health outcomes are caused by interrelated pathways, according to the literature. Cognitive and emotional dysfunction is biologically linked to chronic inflammation, neuroinflammation, hypoxia, and direct neuronal injury, including HIV-associated brain injury, malaria-related immune activation, and induced hippocampal damage. In collectivist sociocultural environments, psychosocial mechanisms, particularly experienced, anticipated, and internalised stigma, promote psychological discomfort, poor treatment adherence, and social isolation. Distress is further compounded by health-system variables such as provider discrimination, a lack of integrated mental health treatments, coercive monitoring techniques, and lengthy treatment burdens. Through gendered blame, carer stress, and courtesy stigma, these effects extend beyond patients to carers and households.

CONCLUSIONS:
In Nigeria and other LMICs, efforts to prevent disease frequently result in biological survival while ignoring the negative effects on mental health caused by biological, social, and systemic processes. Mental health outcomes are not coincidental; rather, they are deeply ingrained in sickness experiences and management techniques. Achieving long-lasting improvements in public health beyond survival requires integrating mental health screening and support in disease control initiatives.