Serum Levels of Cortisol and Adrenocorticotropic Hormone and their Association with Depression in Environmentally Exposed Populations in Kazakhstan.

This study aimed to investigate the serum levels of cortisol and adrenocorticotropic hormone (ACTH) and the prevalence of depression in the environmentally exposed population of Kazakhstan compared to the environmentally unexposed populations. Additionally, the study aimed to evaluate the capacity of cortisol and ACTH to predict moderate and severe depression in populations exposed to environmental risk factors. This cross-sectional study included 1881 nominally healthy individuals aged between 18-52 years who were lifelong residents of Abay, Borodulikha, Ust-Kamenogorsk, Aksay, and Berezovka settlements, which are characterized by exposure to various types of environmental pollutants. Comparisons were made with residents of control sites with no known industrial or radioactive pollution (Uralsk and Kurchum). The Russian version of the PHQ-9 questionnaire was used to evaluate the presence and severity of depression. Serum cortisol levels were measured using solid-phase chemiluminescent immunoassay, while serum ACTH levels were tested with chemiluminescent assays. Populations exposed to environmental pollution from condensate gas extraction (Berezovka and Aksay) had higher median serum cortisol concentrations. However, the populations of the two controls had the highest median serum levels of ACTH. The median total PHQ-9 scores were the lowest in residents of control sites, which also had the highest proportion of individuals with no or minimal depression. Both serum cortisol and ACTH identified moderate, moderately severe, and severe depression. The findings highlight the potential impact of environmental pollution on stress hormone levels and depression, calling for further research and public health interventions to address this issue.