In line with these observations, we reported recently that plasma levels of CXCL12 and chemokine C–X3–C motif ligand 1 (CX3CL1, also referred to fractalkine) are correlated to cocaine symptom severity, which allows stratifying the cocaine addicts in patients with different incidence of comorbid psychiatric disorders (6, 21). Here, CX3CL1 is linked to psychiatric disorder.