When considered alongside the results of observational studies, it may be that CRP itself does not play a causal role in the etiology of depression and that it may be a by-product of other processes playing a true causal role in depression, such as the activation and trafficking of monocytes to the central nervous system, metabolic dysregulation, stress reactivity, substance use or adiposity [81, 95]. Here, CRP is linked to depressive symptom measurement.