Evaluation of undiagnosed depression and inflammatory markers in volunteers submitted to a health questionnaire.

Mental health systems worldwide struggle to meet the needs of their populations, particularly regarding depression, which affects over 300 million people globally. The absence of laboratory diagnoses and adequate treatment complicates coping with this disorder. Varied diagnostic tools and cultural factors also hinder accurate diagnosis. Depression's complex and not fully understood etiopathogenesis is linked to inflammation, as elevated levels of certain inflammatory markers have been observed in affected individuals. This study aimed to analyze the inflammatory profile of patients without a prior depression diagnosis but who scored positively for the disorder on a depression questionnaire. We measured the levels of IL-6, IL-1β, TNF-α, and CRP, alongside anthropometric, health, and lifestyle data. The Depression, Anxiety and Stress Scale (DASS-21) was used to assess the presence of depression. Cytokines IL-6, IL-1β, and TNF-α were measured using chemiluminescence, while CRP was assessed through immunofluorescence. We compared inflammatory markers against the general population's averages and subdivided volunteers into two groups: those with depression and those with depression alongside physical diseases. The nonparametric Mann-Whitney test was applied (p < 0.05). Out of 434 evaluated volunteers, 49 met the criteria for inflammatory profile analysis. The prevalence of undiagnosed depression was found to be 12.9 % [(95 % CI (10.07-16.39)], with approximately 6.12 % in a severe condition and others equally divided between mild and moderate cases. The inflammatory profile revealed that 26.53 % had CRP levels above reference values, 20.40 % for IL-6, 42.85 % for IL-1β, and 77.55 % for TNF-α, particularly highlighting the latter two as potential markers for depression diagnosis. In the analysis of groups with and without associated physical diseases, CRP and IL-6 levels were higher in those with comorbidities, suggesting their relevance as markers in this context. A significant increase in all marker levels was observed in severe depression compared to mild and moderate groups. The high prevalence of unrecognized depression among participants emphasizes the challenges in addressing global depression. Further research is essential to identify specific inflammatory profiles that could serve as indicators for depression, aiding in diagnosis and monitoring the disease's progression.