Figure 1. The research hypothesis at the base of this research study: different status (AAS use, cocaine use, and aging) may be associated to brain damage, generating a miRNA dysregulation. Testing the expression values of several miRNAs involved in important brain functions (miR-21, miR-34, miR-124, miR-132, and miR-144), this study aimed highlighting the differences of these molecular biomarkers among the three tested groups.