SPP1 and depressive symptom measurement: Research has shown that the plasminogen activator inhibitor type 1 gene (SERPINE1) is associated with stress, and mutations in SERPINE1 lead to the development and progression of depression; furthermore, genetic variants of SERPINE1 may cause major depressive disorder susceptibility.[25] An independent analysis of parallel response monitoring showed that SPP1 is associated with the occurrence of depression.[26] According to a machine-learning study, a high level of CCL3 is an inflammatory marker of mood disorders.[27]