FIGURE 1.

Schematic representation showing drug-induced loss of blood brain barrier (BBB) permeability and the associated neurodegeneration. The neurovascular unit and the BBB are affected by various drugs of abuse, which alter vessel permeability via disruption of tight junction proteins complexes (junction adhesion molecules, endothelial cell-selective adhesion molecules, occludins, and claudins), transport systems, and intracellular signaling. BBB disruption, which affects immune cell transmigration and neuroinflammation and contributes to an imbalanced redox system, affects the brain’s microenvironment and homeostasis, leading to neurotoxicity (Created with Biorender.com).